HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Figures Only Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kundra, V. Articles by Silverman, S. G. Search for Related Content PubMed PubMed Citation Articles by Kundra, V. Articles by Silverman, S. G.

Telomerase Activity Predicts Malignancy in Percutaneous Image-guided Needle Biopsy Specimens of the Abdomen and Pelvis¹

¹ From the Division of Abdominal Imaging and Intervention, Department of Radiology (V.K., P.N., D.S.G., K.H.Z., K.T., E.v.S., S.G.S.) and Division of Cytology, Department of Pathology (J.F.K.), Brigham and Women’s Hospital, Harvard Medical School, Boston, Mass. Received October 30, 2003; revision requested January 13, 2004; revision received April 7; accepted May 24. Supported in part by the Wylie J. Dodds Research Grant awarded by the Society of Gastrointestinal Radiologists in 2000. Address correspondence to V.K., Division of Diagnostic Imaging, Box 57, M. D. Anderson Cancer Center, University of Texas, 1515 Holcombe Blvd, Houston, TX 77030 (e-mail: vkundra@di.mdacc.tmc.edu).

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
PURPOSE: To determine prospectively if assessment of telomerase activity in percutaneous needle biopsy specimens improves sensitivity and specificity in the diagnosis of abdominal and pelvic malignancy.

MATERIALS AND METHODS: The study was approved by the institutional review board, and written informed consent was obtained from all patients. A prospective double-blinded design was used to assess telomerase activity in abdominal and pelvic biopsy specimens from 99 patients (64 men, 35 women; age range, 22–87 years). After the clinical sample was retrieved, a study specimen from an extra needle pass was divided and independently analyzed for cytologic characteristics and telomerase activity. The final diagnosis was based on chart review at a minimum 1-year follow-up. Statistical analyses included sensitivity, specificity, and accuracy of cytologic examination and/or telomerase activity in predicting malignancy.

RESULTS: Data from study specimens indicated that the sensitivity, specificity, and accuracy of telomerase activity (n = 99) in predicting malignancy were 55%, 79%, and 60%, respectively. For cytologic examination (n = 86), the sensitivity, specificity, and accuracy in predicting malignancy were 74%, 94%, and 78%, respectively. Combining the two tests (n = 86) and classifying a positive reading with either test as malignant improved sensitivity (83%) (P < .05) without altering specificity (76%). In 20 patients who had clinical sample reports that were classified as indeterminate, telomerase activity (n = 20) yielded a higher sensitivity (62%) (P < .05) and similar specificity (86%) compared with cytologic examination (n = 15), which yielded a sensitivity of 11% and a specificity of 83%.

CONCLUSION: In percutaneous biopsy specimens of the abdomen and pelvis, the combination of cytologic examination and telomerase activity yielded an increased sensitivity in predicting malignancy. In addition, assessing telomerase activity can help identify cancer even when cytologic results are indeterminate.

© RSNA, 2005

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
Although image-guided percutaneous biopsy of abdominal and pelvic masses is a safe and effective procedure, certain lesions, including lymphoma (1,2), sarcoma (3,4), and epithelial tumors such as those that manifest in the pancreas (5,6), may be difficult to diagnose. False-negative results are more common than false-positive results (5–9). An inadequate quantity of cellular material or poor cellular preservation may preclude a definitive diagnosis at cytologic examination. Even after obtaining specimens thought to be adequate at the time of biopsy, investigators have noted that 7%–30% of cytologic reports return an indeterminate result, such as "suspicious, atypical, or insufficient sample" (8,10–12). Indeterminate biopsy results often put clinicians in a quandary as to how to proceed because these results cannot be classified simply as positive or negative. For example, Maitra et al (7) found that 42% of mesenchymal lesions deemed suspicious at biopsy were in fact benign. Additional assays are needed to improve the test characteristics of percutaneous abdominal biopsy and to reduce the number of indeterminate results.

Novel assays that capitalize on basic cellular processes, such as limited replication, are being developed to distinguish malignancy. Unlike cancer cells, normal somatic cells have a restricted life span. With each cell division, the ends of chromosomes, called telomeres, become smaller. This is because the RNA primer that is necessary to prime DNA replication is degraded at the 5' end (13). Therefore, no replication occurs at the telomeres, and the chromosome shortens with each replication cycle (14). Eventually, critical genes are affected, and the cell stops growing or dies. Because tumor cells divide indefinitely, they must overcome the end replication problem. This is most often accomplished by activating the ribozyme telomerase, which adds nucleotides in units of six base pair repeats to the ends of DNA, thereby lengthening the telomere (15–17) and, thus, increasing the life span of the cell.

Because unlimited rounds of cell division are a basic requirement for cancer, it is not surprising that telomerase activity has been found in most malignancies. Telomerase activity is also found in germ cells, which undergo unlimited replication as well (1). In addition, telomerase activity is found at low levels in blood cells, (18,19) such as lymphocytes, presumably because these cells must undergo clonal expansion similar to that of stem cells. Telomerase activity, however, is either absent or present in low amounts in normal tissues and benign neoplasms (20). In surgical specimens, telomerase activity has been found in a majority of malignant tumors (20–22), including those that manifest in the breast (22), colon (23), liver (24), brain (25), prostate (26), and lung (27). Only a limited number of studies, however, have evaluated telomerase activity in needle biopsy specimens, and these studies have focused primarily on breast lesions and hepatocellular carcinoma (28–31). Prior studies have primarily evaluated specific tumors and adjacent normal tissue. To the best of our knowledge, a more generalized sample of percutaneous image-guided abdominal and pelvic biopsies has not been studied in a clinical setting.

Currently, samples from percutaneous needle biopsies of the abdomen are analyzed by using cytologic criteria alone. An adequate sample size is required. In addition, knowledge of the morphologic characteristics of individual cells and their surrounding milieu is essential to render a diagnosis. In comparison, telomerase activity is demonstrated by using cell lysates; thus, the preservation of cellular morphologic features is not necessary. Furthermore, only a small sample is needed to demonstrate the presence of the functioning ribozyme. Telomerase activity is assessed primarily by using the telomerase repeat amplification protocol assay, or modifications thereof, which provides high sensitivity (32). Mixing telomerase-negative cells with telomerase-positive cells does not interfere with discerning telomerase activity (33). Thus, the purpose our study was to determine prospectively if assessment of telomerase activity in percutaneous needle biopsy specimens improves sensitivity and specificity in the diagnosis of abdominal and pelvic malignancy.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
Study Design
A prospective, double-blinded protocol schema (Fig 1) was followed after approval by the institutional review board. Written informed consent was obtained from all patients included in this study. At the time of the procedure, a cytopathologist or cytopathology technician reviewed the biopsy sample for adequacy for diagnosis. After adequate clinical samples were obtained, the localizing needle or an additional needle was used to obtain one additional biopsy sample, which served as the study specimen. The specimen was dispersed into a culture medium (RPMI 1640; Invitrogen Life Technologies, Carlsbad, Calif) and divided for independent blinded analysis of cytologic characteristics and telomerase activity. Patients were followed up for at least 1 year. The final diagnosis was determined by using chart review, including subsequent imaging, surgery, repeat biopsy, or clinical disposition. After independent blinded chart review, cytologic analysis, and telomerase activity assessment, data from 99 patients were combined for statistical analysis.

View larger version (16K): [in this window] [in a new window] [Download PPT slide]   Figure 1. Protocol schema. After the clinical biopsy sample was retrieved, a study specimen was obtained from an extra needle pass. Study specimen was divided and independently analyzed for cytologic characteristics and telomerase activity. Results from cytologic examination and telomerase assay of the study specimen were then compared with results of the clinical biopsy sample and chart review at a minimum 1-year follow-up.

Biopsy
Biopsies were performed with computed tomographic guidance (34) by a team that consisted of one of 10 abdominal staff radiologists (each with more than 3 years of experience) and a fellow who was training in abdominal intervention. For all of the biopsies, Chiba needles were used (Cook, Bloomington, Ind). The majority of the biopsies were performed with either a 20-gauge needle (n = 30) or a 22-gauge needle (n = 34). The remainder of the procedures (n = 35) was performed with a combination of needles ranging from 16 to 25 gauge. All study specimens, however, were obtained by using fine needles measuring 20 gauge or 22 gauge. Biopsies were performed of a broad range of abdominal and pelvic sites (Table 1).

Telomerase Assay
The portion of the study specimen that was divided for the assessment of telomerase activity (20) was centrifuged at 10 000g for 1 minute at 4°C. The ensuing pellet was frozen at –70°C until used. To measure telomerase activity, we used a combined polymerase chain reaction and enzyme-linked immunosorbant assay method (TeloTAGGG; Roche, Basel, Switzerland), which was performed according to the manufacturer’s instructions. After specimen lysis and centrifugation, the supernatant was assessed for protein concentration by using the Bradford method (Biorad, Hercules, Calif). To maximize signal, a large amount of protein (2.5 µg) was evaluated in the assay. The enzyme Taq is necessary for the polymerase chain reaction portion of the assay. Because Taq inhibitors are found in tissues, each specimen was also evaluated by using a small amount of protein (0.5 µg) to dilute any Taq inhibitors. At the end of the assay, each specimen was definitively classified as malignant if the optical density measurement using either the 2.5-µg or 0.5-µg specimen extract was greater than that of the negative control, which consisted of human IMR-90 fibroblast cell extract (20). Specimens were definitively classified as benign if the optical density was less than or equal to that of the negative control (20). Assays were evaluated by a single author (V.K.) who had 4 years experience with telomerase activity assays and 1 year experience with the TeloTAGGG assay.

Chart Review
Charts were reviewed by a single author (D.S.G.) for at least 1 year after biopsy to determine final diagnoses on the basis of subsequent biopsy results, surgical findings, pathology reports, further imaging studies, and clinical disposition. A result was considered true-positive if findings were positive for malignancy at testing (cytologic examination, telomerase activity assay, or cytologic examination and telomerase activity assay combined) and positive for malignancy at final diagnosis per chart review. A result was considered false-positive if findings were positive for malignancy at testing but negative for malignancy at final diagnosis. A result was considered true-negative if findings were negative for malignancy at testing and negative for malignancy at final diagnosis. A result was considered false-negative if findings were negative for malignancy at testing but positive for malignancy at final diagnosis.

Statistical Analysis
Statistical methods included summary statistics, diagnostic sensitivity and specificity, the McNemar test based on contingency tables, and stratified analyses (K.H.Z., 7 years of postdoctoral experience). Statistical analysis was performed by using a statistical software program (Splus 6.0; Insightful, Seattle, Wash). A two-tailed t test was used to compare the study population age of men with that of women. Summary statistics of test characteristics were computed. Frequency distributions of the biopsy results by procedure were estimated on the basis of an analysis of counts and contingency tables.

Because indeterminate results cannot be interpreted as positive or negative for malignancy, only the definitive results were included in the statistical analysis. Sensitivity, specificity, and accuracy of diagnostic methods were correlated with chart review and compared with study specimen results of cytologic examination alone, telomerase activity alone, and a combination of these two. Test characteristics were computed on the basis of the analysis of proportion in a contingency table. All pair-wise statistical comparisons of the correlated sensitivities (or specificities) of any of the two diagnostic methods were conducted by using the McNemar test.

In addition, to evaluate the added value of telomerase activity and cytologic examination combined, we adopted a logic combination rule so that a combined result was considered positive if either diagnostic test yielded a positive result. The added value of telomerase activity and cytologic examination combined was compared statistically with cytologic examination alone by using the McNemar test.

We evaluated whether assaying telomerase activity provided further information about patients in whom clinical biopsy results were indeterminate. Test characteristics of telomerase activity and cytologic examination were evaluated in this subgroup of indeterminate study specimens and were compared with chart review.

Results that were negative on the basis of both cytologic findings and telomerase activity but malignant on the basis clinical follow-up suggest that the extra needle pass failed to sample, or "missed," the lesion. A subset of data that excluded these missed lesions was, therefore, analyzed separately. The results from the hypothesis tests were considered statistically significant when P .05.

	RESULTS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
Biopsy Findings
Biopsies were performed at a number of different locations in the abdomen and pelvis and yielded a variety of malignant and benign tissues. Benign biopsy findings were obtained from the liver, adrenal glands, lymph nodes, spleen, presacral region, and a peritoneal mass (Table 2). As seen in Table 3, the most common malignant diagnosis was renal cell carcinoma, followed by colorectal carcinoma, lung carcinoma, and lymphoma.

Telomerase Activity
Figure 2, which shows a plot graph of all biopsy results, demonstrates that there was wide variation in the level of telomerase activity among specimens with true-positive findings. This wide variation was found regardless of whether the clinical biopsy sample was classified as definitive or indeterminate. In benign lesions, little or no telomerase activity was detected. A high level of telomerase activity, however, was found in one adrenal adenoma. Notably, telomerase activity was low at the other three false-positive sites. Two sites in the liver had vasculitis or marked acute and chronic inflammation. The third site was a desmoid tumor, which is a benign, though potentially locally recurrent, lesion. The data imply that the absolute amount of telomerase activity may not be as important as simply the presence of telomerase activity in predicting malignancy in percutaneous biopsy specimens of the abdomen and pelvis.

View larger version (24K): [in this window] [in a new window] [Download PPT slide]   Figure 2. Graph demonstrates the semiquantitative analysis of telomerase activity in percutaneous biopsy specimens of the abdomen and pelvis. When the final diagnosis was positive for malignancy (FD+), there was wide variation in the amount of telomerase activity found in clinical samples (CS) that were classified as either definitive or indeterminate for cancer. In a number of samples, telomerase activity was measurable by using only one of the two amounts of protein (2.5 or 0.5 µg) from the study specimen. FD– = final diagnosis negative for malignancy, O.D. = optical density.

	DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 
Although percutaneous biopsy of the abdomen and pelvis is a powerful technique, some lesions may be difficult to diagnose, and biopsy may yield only minute amounts of tissue (1–4,8,10–12). Cytologic analysis is dependent on an adequate sample quantity and preserved morphologic features. Because determination of telomerase activity requires a small sample and uses cell lysates, we assessed whether telomerase activity may serve as an adjunct to cytologic examination. In this study, we evaluated a wide range of tissues that were clinically relevant to image-guided percutaneous biopsy of the abdomen and pelvis. Data from these tissues demonstrated that the presence of telomerase activity augmented cytologic examination in the diagnosis of cancer. Classifying a positive reading by either telomerase activity or cytologic examination as malignant increased the sensitivity for diagnosing cancer without significantly altering specificity. In addition, even when cytologic results were indeterminate, the presence of telomerase activity identified malignant lesions.

In clinical practice, percutaneous biopsy results of the abdomen are indeterminate in 7%–30% of biopsy samples (8–11), and sometimes a negative result may be spurious. Among percutaneous biopsies of the adrenal gland, Silverman et al (12) identified three malignancies in 33 lesions that had cytologic findings interpreted as benign. In addition, Silverman et al found two malignancies in 14 samples that were classified as nondiagnostic (12). In our study, the assessment of telomerase activity helped identify malignancy in six of 86 study specimens deemed negative at cytologic examination.

Measurement of telomerase activity also aided the analysis of lesions considered indeterminate at cytologic examination. Among image-guided percutaneous biopsy specimens of the abdomen, Phillips et al (35) obtained true-negative findings in 78%, 66%, and 29% of normal or benign, nondiagnostic, and atypical results, respectively. Others have found that approximately 58% of suspicious lesions are malignant (7). Classifying all lesions considered indeterminate at cytologic examination as negative for malignancy lowers sensitivity, whereas classifying such lesions as positive for malignancy lowers specificity. Thus, it would be beneficial to parse lesions that are deemed indeterminate at cytologic examination in a more predictive fashion. In our data set, 20% of the clinical biopsy reports were indeterminate. In this subgroup, however, telomerase activity was found in a majority of malignancies (eight true-positive findings in 13 malignant lesions) but not in almost all benign lesions (one false-positive finding in seven benign lesions).

During percutaneous biopsy, it is standard practice to perform multiple needle passes to obtain a sufficient sample for cytologic analysis. Gothlin and Gadeholt (36) demonstrated that a single needle pass is often insufficient to obtain diagnostic material. Thus, the single needle that was used to obtain the study specimen may have missed the lesion, thereby resulting in an incorrect diagnosis on the basis of telomerase activity and cytologic analysis. Therefore, a specimen may be labeled as negative on the basis of findings from both tests even though the lesion is, in fact, malignant. Indeed, when these missed lesions were excluded, the sensitivity of telomerase activity increased from 55% to 65%, and the sensitivity of cytologic examination increased from 74% to 89%. Likewise, an indeterminate result at cytologic examination may also be caused by a missed lesion. After we excluded results that were both negative or indeterminate at cytologic examination and negative at telomerase assessment but positive at chart review, the sensitivity of telomerase activity increased to 71% (44 of 62 lesions), specificity remained at 79% (15 of 19 lesions), and accuracy increased to 72% (59 of 81 lesions).

The test characteristics that are noted for telomerase activity are similar to those noted in the literature. In surgical specimens, telomerase activity was found in 69% of renal cell carcinomas, 90% of bladder cancers, and 90% of prostate cancers. By comparison, telomerase activity was present in 2% of renal samples, 27% of bladder samples, and 38% of prostate samples that were considered benign (37). The sensitivity of telomerase activity in demonstrating cancer in percutaneous needle biopsies of breast lesions ranged from 72% to 92%, and specificity was up to 94% (38). Nouso et al (30) identified telomerase activity in 84% of needle biopsy specimens of hepatocellular carcinoma. In surgical specimens, Nouso et al found a low level of activity in 17% of chronic hepatitis cases (30). In transcervical needle biopsies, telomerase activity was found to have a sensitivity of 86% and specificity of 100% in the differentiation of uterine leiomyosarcomas from leiomyomas (39). Investigators from a previous study (40) found telomerase activity in 63% of lung cancer biopsy samples obtained at bronchoscopy. Although there was some overlap with findings in normal tissue, the amount of activity was greater in lung tumors (40).

As in the above articles, the degree of telomerase activity in our biopsy specimens varied. Low telomerase activity was found in some benign lesions; however, this was also true of some cancers. By comparison, high telomerase activity was found almost exclusively in malignancies. However, one benign lesion, an adrenal cortical adenoma, had high activity. This is an unusual finding. Bamberger et al (41) previously reported that benign and malignant primary adrenal lesions have predominantly low levels of telomerase activity that are similar to those of normal adrenal tissue. If increased specificity is needed, a higher threshold value may be used to determine the presence of telomerase activity. In turn, this would also decrease sensitivity for malignancy.

Performing the telomerase assay by using both a large (2.5-µg) and a small (0.5-µg) amount of protein increased the number of true-positive results. Although most positive results were obtained when either amount of protein was used, findings from some samples were positive with only one amount. The latter was slightly more common with the smaller amount, which is consistent with dilution of Taq inhibitors that stymie the polymerase chain reaction portion of the assay. Thus, because either amount can be informative, it is advantageous to use the two different amounts of protein for the telomerase assay.

One of the limitations of this study is that some of the patients were followed up for only 1 year. Although unlikely, it is possible that a slow-growing cancer may require more than a year to manifest an appreciable change in size. A second limitation of this study is that the pretest probability of malignancy was not recorded for each case. This may influence the decision to perform a repeat biopsy if a negative or indeterminate result is obtained at cytologic examination. If the pretest probability was very high, we may have overestimated the value of telomerase activity assessment. In most circumstances, however, lesions with low pretest probability do not undergo biopsy. In this study, the likelihood of selecting a population with only one type of pretest probability was low because patients who met the criteria and agreed to participate in the study were enrolled consecutively.

A third limitation is that the sample size that was used to calculate specificity was small. In our data set, however, there was no statistically significant difference in the specificity of cytologic examination alone versus cytologic examination and telomerase activity combined in demonstrating malignancy. In clinical practice, sensitivity is more important than specificity at the time of biopsy. The goal is to find all cancers. If cytologic findings are positive for malignancy, the patient may proceed with treatment. However, if cytologic findings are negative or indeterminate and telomerase activity is found, the data suggest that the patient should undergo repeat biopsy or close clinical follow-up. In this study, we used only fine needles for biopsy. The use of large needles to obtain more sample, which then could have undergone histologic evaluation, may have increased the sensitivity and specificity of the biopsy and of the telomerase assay. The effect of using large needles awaits further assessment.

In this study, we evaluated a number of organs and a spectrum of benign and malignant lesions of the abdomen and pelvis to determine whether assessment of telomerase activity to distinguish malignancy has broad applicability. The test for telomerase activity measures a different parameter than standard cytologic techniques. Unlike cytologic evaluation, which depends on an adequate sample quantity and cellular preservation, evaluation of telomerase activity is performed by using cell lysates and requires a minute sample. Thus, the two tests complement each other. In percutaneous biopsy specimens of the abdomen and pelvis, the combination of cytologic examination and telomerase activity yielded increased sensitivity in predicting malignancy; furthermore, our findings show that even when cytologic results are indeterminate, assaying telomerase activity can help identify cancer. Although we did obtain a small number of false-positive results by using the telomerase assay, the data imply that in a clinical setting, if cytologic results are negative or indeterminate, the presence of telomerase activity supports the diagnosis of malignancy and should prompt further investigation, such as a repeat biopsy or close clinical follow-up.

	FOOTNOTES

 
² Current address: Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Ill.

Authors stated no financial relationship to disclose.

Author contributions: Guarantor of integrity of entire study, V.K.; study concepts and design, V.K., J.F.K., P.N., K.T., E.v.S., S.G.S.; literature research, V.K., D.S.G., S.G.S.; clinical studies, all authors; data acquisition and analysis/interpretation, all authors; statistical analysis, V.K., K.H.Z.; manuscript preparation, definition of intellectual content, editing, revision/review, and final version approval, all authors

	REFERENCES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION REFERENCES

 

1. Grosso LE, Collins BT, Dunphy CH, Ramos RR. Lymphocyte-depleted Hodgkin’s disease: diagnostic challenges by fine-needle aspiration. Diagn Cytopathol 1998; 19:66-69.[CrossRef][Medline]
2. Quinn SF, Sheley RC, Nelson HA, Demlow TA, Wienstein RE, Dunkley BL. The role of percutaneous needle biopsies in the original diagnosis of lymphoma: a prospective evaluation. J Vasc Interv Radiol 1995; 6:947-952.[Medline]
3. Lopez-Rios F, Perez-Barrios A, Alberti N, Vargas J, Lozano F, de Agustin P. Fine-needle aspiration biopsy of the retroperitoneum: a series of 111 cases not including specific organs. Diagn Cytopathol 2002; 27:85-89.[CrossRef][Medline]
4. Nemanqani D, Mourad WA. Cytomorphologic features of fine-needle aspiration of liposarcoma. Diagn Cytopathol 1999; 20:67-69.[CrossRef][Medline]
5. Tillou A, Schwartz MR, Jordan PH, Jr. Percutaneous needle biopsy of the pancreas: when should it be performed? World J Surg 1996; 20:283-286.[CrossRef][Medline]
6. Cruz F, Soffia P, del Rio P, et al. Computed tomography guided fine needle aspiration biopsies. Rev Med Chil 1992; 120:1254-1260.[Medline]
7. Maitra A, Ashfaq R, Saboorian MH, Lindberg G, Gokaslan ST. The role of fine-needle aspiration biopsy in the primary diagnosis of mesenchymal lesions: a community hospital-based experience. Cancer 2000; 90:178-185.[CrossRef][Medline]
8. Reddy VB, Gattuso P, Abraham KP, Moncada R, Castelli MJ. Computed tomography-guided fine needle aspiration biopsy of deep-seated lesions: a 4-year experience. Acta Cytol 1991; 35:753-756.[Medline]
9. Donadi M, Rabassini A, Ciarmiello G, Dal Pozzo A, Bacarini L, Lise F. The echo-guided fine-needle biopsy of thoracic and abdominal masses. Radiol Med (Torino) 1991; 82:604-608.
10. Sheikh M, Sawhney S, Dey P, al-Saeed O, Behbehani A. Deep-seated thoracic and abdominal masses: usefulness of ultrasound and computed tomography guidance in fine needle aspiration cytology diagnosis. Australas Radiol 2000; 44:155-160.[CrossRef][Medline]
11. Jan GM, Mahajan R. Ultrasound guided percutaneous fine needle aspiration biopsy (FNAB) of intraabdominal and retroperitoneal masses. Indian J Gastroenterol 1989; 8:99-100.[Medline]
12. Silverman SG, Mueller PR, Pinkney LP, Koenker RM, Seltzer SE. Predictive value of image-guided adrenal biopsy: analysis of results of 101 biopsies. Radiology 1993; 187:715-718.[Abstract/Free Full Text]
13. Watson JD. Origin of concatemeric T7 DNA. Nature New Biol 1972; 239:197-201.[CrossRef][Medline]
14. Olovnikov AM. A theory of marginotomy: the incomplete copying of template margin in enzymatic synthesis of polynucleotides and biological significance of the phenomenon. J Theor Biol 1973; 41:181-190.[CrossRef][Medline]
15. Greider CW, Blackburn EH. Identification of a specific telomere terminal transferase activity in Tetrahymena extracts. Cell 1985; 43:405-413.[CrossRef][Medline]
16. Morin GB. Recognition of chromosome truncation site associated with alpha-thalasesmia by human telomerase. Nature 1991; 353:454-456.[CrossRef][Medline]
17. Morin GB. The human telomerase terminal transferase enzyme is a ribonucleoprotein that synthesizes TTAGGG repeats. Cell 1989; 59:521-529.[CrossRef][Medline]
18. Hiyama K, Hirai Y, Kyoizumi S, et al. Activation of telomerase in human lymphocytes and hematopoietic progenitor cells. J Immunol 1995; 155:3711-3715.[Abstract]
19. Weng NP, Levine BL, June CH, Hodes RJ. Regulated expression of telomerase activity in human T lymphocyte development and activation. J Exp Med 1996; 183:2471-2479.[Abstract/Free Full Text]
20. Kim NW, Piatyszek MA, Prowse KR, et al. Specific association of human telomerase activity with immortal cells and cancer. Science 1994; 266:2011-2015.[Abstract/Free Full Text]
21. Kyo S, Kanaya T, Ishikawa H, Ueno H, Inoue M. Telomerase activity in gynecological tumors. Clin Cancer Res 1996; 2:2023-2038.[Abstract]
22. Hiyama E, Gollahon L, Kataoka T, et al. Telomerase activity in human breast tumors. J Natl Cancer Inst 1996; 88:116-122.[Abstract/Free Full Text]
23. Chadeneau C, Hay K, Hirte HW, Gallinger S, Bacchetti S. Telomerase activity associated with acquisition of malignancy in human colorectal cancer. Cancer Res 1995; 55:2533-2536.[Abstract/Free Full Text]
24. Tahara H, Nakanishi T, Kitamoto M, et al. Telomerase activity in human liver tissues: comparison between chronic liver disease and hepatocellular carcinomas. Cancer Res 1995; 55:2734-2736.[Abstract/Free Full Text]
25. Langford LA, Piatyszek MA, Xu R, Schold SC, Jr, Shay JW. Telomerase activity in human brain tumors. Lancet 1995; 346:1267-1268.[CrossRef][Medline]
26. Sommerfeld HJ, Meeker AK, Piatyszek MA, Bova GS, Shay JW, Coffey DS. Telomerase activity: a prevalent marker of malignant human prostate tissue. Cancer Res 1996; 56:218-222.[Abstract/Free Full Text]
27. Hiyama K, Hiyama E, Ishioka S, et al. Telomerase activity in small-cell and non-small-cell lung cancer. J Natl Cancer Inst 1995; 87:895-902.[Abstract/Free Full Text]
28. Sugino T, Yoshida K, Bolodeoku J, et al. Telomerase activity in human breast cancer and benign breast lesions: diagnostic applications in clinical specimens, including fine needle aspirates. Int J Cancer 1996; 69:301-306.[CrossRef][Medline]
29. Nakashio R, Kitamoto M, Tahara H, Nakanishi T, Ide T, Kajiyama G. Significance of telomerase activity in the diagnosis of small differentiated hepatocellular carcinoma. Int J Cancer 1997; 74:141-147.[CrossRef][Medline]
30. Nouso K, Urabe Y, Higashi T, et al. Telomerase as a tool for the differential diagnosis of human hepatocellular carcinoma. Cancer 1996; 78:232-236.[CrossRef][Medline]
31. Takahashi C, Miyagawa I, Kumano S, Oshimura M. Detection of telomerase activity in prostate cancer by needle biopsy. Eur Urol 1997; 32:494-498.[Medline]
32. Wright WE, Shay JW, Piatyszek MA. Modifications of a telomeric repeat amplification protocol (TRAP) result in increased reliability, linearity and sensitivity. Nucleic Acid Res 1995; 23:3794-3795.[Free Full Text]
33. Bryan TM, Englezou A, Gupta J, Bacchetti S, Reddel RR. Telomerase elongation in immortalized human cells without detectable telomerase activity. EMBO J 1995; 14:4240-4248.[Medline]
34. Gazelle GS, Haaga JR. Guided percutaneous biopsy of intraabdominal lesions. AJR Am J Roentgenol 1989; 153:929-935.[Free Full Text]
35. Phillips MD, Silverman SG, Cibas ES, Seltzer SE. Negative predictive value of imaging-guided abdominal biopsy results: cytologic classification and implications for patient management. AJR Am J Roentgenol 1998; 171:693-696.[Abstract/Free Full Text]
36. Gothlin JH, Gadeholt G. Percutaneous fine needle biopsy of abdominal and pelvic lesions: passes necessary for secure diagnosis with fluoroscopy and CT-guidance. Eur J Radiol 1986; 6:288-290.[Medline]
37. Orlando C, Gelmini S, Selli C, Pazzagli M. Telomerase activity in urological malignancy. J Urol 2001; 166:666-673.[CrossRef][Medline]
38. Poremba C, Shroyer KR, Frost M, et al. Telomerase is a highly sensitive and specific molecular marker in fine-needle aspirates of breast lesions. J Clin Oncol 1999; 17:2020-2026.[Abstract/Free Full Text]
39. Tsujimura A, Kawamura N, Ichimura T, Honda K, Ishiko O, Ogita S. Telomerase activity in needle biopsied uterine myoma-like tumors: differential diagnosis between uterine sarcomas and leiomyomas. Int J Oncol 2002; 20:361-365.[Medline]
40. Hirashima T, Yoshitaka O, Nitta T. Telomerase activity in endoscopically visible lung cancer. Anticancer Res 2001; 21:3685-3689.[Medline]
41. Bamberger CM, Else T, Bamberger AM, et al. Telomerase activity in benign and malignant adrenal tumors. Exp Clin Endocrinol Diabetes 1999; 107:272-275.[Medline]

This article has been cited by other articles:

				S. G. Silverman, Y. U. Gan, K. J. Mortele, K. Tuncali, and E. S. Cibas Renal Masses in the Adult Patient: The Role of Percutaneous Biopsy Radiology, July 1, 2006; 240(1): 6 - 22. [Abstract] [Full Text] [PDF]

This Article Abstract Figures Only Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kundra, V. Articles by Silverman, S. G. Search for Related Content PubMed PubMed Citation Articles by Kundra, V. Articles by Silverman, S. G.