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Letters to the Editor |
Northwest Radiology Associates, 800 West Central Road, Arlington Heights, IL 60005, e-mail: kalbhen@medscape.com
Editor:
The State of the Art article by Dr Ascher and colleagues in the January 2000 issue of Radiology (1) is timely and important. The authors have succinctly summarized the relevant data supporting the use of tamoxifen citrate as both a chemotherapeutic and chemopreventive agent for breast cancer, and they have provided an excellent detailed review of the histopathologic and imaging findings of the associated uterine abnormalities. More important, Dr Ascher and colleagues have described an algorithm for endometrial imaging in postmenopausal women undergoing tamoxifen therapy. This type of protocol has the potential to be useful to both radiologists and referring clinicians. Unfortunately, the presented algorithm has shortcomings.
Tamoxifen citrate is typically administered continuously for years at a time. Dr Ascher and colleagues have not stated whether imaging should be performed once or if it should be repeated at fixed intervals. Because the risk of endometrial cancer increases with duration of treatment and cumulative tamoxifen dose (1), regular screening is probably prudent. Screening could be performed concurrently with yearly mammography, although I know of no data specifically supporting annual uterine imaging in patients receiving tamoxifen.
Dr Ascher and colleagues have chosen 4 mm as the upper limit of normal endometrial thickness at transvaginal ultrasonography (US); hysterosonography is recommended for patients with an endometrial thickness of 5 mm or greater. Fewer than 1% of women who undergo tamoxifen therapy are likely to have transvaginal US endometrial thicknesses of 4 mm or less (2–4). Therefore, Dr Ascher and colleagues are essentially advocating hysterosonography for all patients receiving tamoxifen. Hysterosonography is generally a safe and well-tolerated procedure. However, in comparison with transvaginal US, hysterosonography causes more patient discomfort, has a higher risk of infection, is more expensive, and requires a substantially greater investment of the radiologist’s time.
In the United States, there are "potentially tens of millions of women" who may be candidates for tamoxifen therapy (5). Unfortunately, there are only approximately 20,000 practicing radiologists (6), and the majority are not proficient in hysterosonography. Therefore, the recommended protocol would be, at best, difficult to implement with the available level of expertise. For these reasons, and acknowledging a resultant loss in sensitivity, I believe that a transvaginal US endometrial thickness of 8 mm or less (including both the normal and equivocal categories described by Dr Ascher and colleagues [1]) should obviate further work-up in the absence of uterine bleeding.
In conclusion, while I applaud the efforts of Dr Ascher and colleagues in creating an imaging algorithm for postmenopausal women undergoing tamoxifen therapy, I believe that endometrial screening should be performed at regular intervals, possibly yearly, and should include hysterosonography only for patients with bleeding or with transvaginal US endometrial thicknesses greater than 8 mm. With additional data and experience, these recommendations are likely to be modified.
REFERENCES
and
Janice M. Lage, MD,
Departments of Radiology* and Pathology, Georgetown University Medical Center, 3800 Reservoir Road NW, Washington, DC 20007-2197, e-mail: aschers@gunet.georgetown.edu, Department of Radiology, Shimane Medical University, Japan
We read Dr Kalbhen’s letter with interest and would like to respond to his concerns.
First, the American College of Obstetricians and Gynecologists (1) does not advocate that asymptomatic women who receive tamoxifen citrate undergo endometrial surveillance. For that reason, we did not choose an arbitrary screening interval to image women receiving tamoxifen citrate but underscored the need for a multidisciplinary (ie, patient, oncologist, gynecologist, radiologist) approach to imaging the uterus.
Second, the normal endometrial width in women receiving tamoxifen citrate is controversial (eg, the largest study [2] to date, to our knowledge, had only 111 patients). In light of this, we chose a conservative upper limit of less than 5 mm (as opposed to 
8 mm) for the normal endometrium, although we agree that if every woman receiving tamoxifen citrate were screened yearly, the radiology community might be overwhelmed. However, that theoretic prospect does not affect our judgment about the most appropriate work-up for these women any more than the prospect of overwhelming the radiology community affects the shared view that every woman eligible for annual mammographic examination should undergo one.
Third, we agree with Dr Kalbhen that if screening were deemed appropriate, bundling yearly mammography with US would be a sound idea.
As for the algorithm, it evolved during the review process on the basis of recommendations from expert reviewers; however, we do agree that with additional experience and data, our recommendations are likely to be modified.
Our goals for writing this article were to educate radiologists about uterine imaging features in women receiving tamoxifen citrate and to begin a dialogue within the imaging community and with our clinical colleagues about surveying the uterus in these women, especially given the results of the National Surgical Adjuvant Breast and Bowel Project P-1 Study (3).
REFERENCES
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