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Letters to the Editor |
Department of Internal Medicine, Ospedale Maggiore, Largo B. Nigrisoli 2, Bologna, Emilia Romagna 40133, Italy
e-mail: vincenzo.arienti{at}unibo.it
We read the article "Image-guided Tumor Ablation: Standardization of Terminology and Reporting Criteria" (1) by Dr Goldberg and colleagues with interest. This article appeared in the June 2005 issue of Radiology.
The goal of the International Working Group on Image-guided Tumor Ablation was to standardize terms and methods to be used by all clinicians who practice ablation treatments. In fact, worldwide adoption of this common language framework will lead to improved accuracy in communication and comparison of the results of different therapies, thereby giving us the opportunity to maximize patient outcomes. The huge effort made by the group has been rewarded by the resonance that this article has gained among the great majority of physicians involved in this field.
As the authors also stated that standardization of terminology is an ongoing process and that they welcome constructive feedback from the medical community to further refine the unresolved issues, we would like to make two comments regarding the section in their article dedicated to complications.
First, our attention was drawn to the authors' definition of tumor seeding as either a major or a minor complication, depending on whether the ectopic tumor focus can be successfully ablated or otherwise treated. Tumor seeding after percutaneous image-guided ablation represents a major issue in the literature, as documented by more than 30 articles on this topic published in the previous 5 years (per a MEDLINE search of "seeding," "Hcc," and "radiofrequency" in articles published in 2000–2005 [2]). In a poorly controlled disease like cancer, the relevance of seeding is generally perceived, by both patients and clinicians, as an unfavorable event that is probably second only to death. The dissemination of cancer cells, following an invasive procedure, represents not only a complication or a treatment failure of the generalized disease but, above all, a true worsening of the patient's condition. There is no doubt, from an oncologic point of view, that iatrogenic seeding is an upstaging of the disease even if the ectopic tumor nodule can be successfully treated by means of repeat ablation, surgery, radiation therapy, or chemotherapy (3). Moreover, we cannot exclude microscopic cancer cell foci concomitant to the seeding nodule by means of current imaging techniques (4), and this fact contributes to making the event serious and must not be underestimated.
According to the unified standardized Society of Interventional Radiology grading system (5) and to the authors' reporting criteria, seeding treated by means of ablation should be classified as a minor complication (classifications A and B) while, for example, a case of an arteriobiliary fistula, treated by means of embolization and definitely cured, should be included as a major complication (classifications C–E). In our opinion, the first condition cannot be classified at a lower level than the second. As a consequence of the above considerations, and according to the definition of a major complication (an event that leads to substantial morbidity and disability) reported in the same article, we believe there is therefore enough evidence to classify any episode of tumor seeding as a major complication.
Second, we would like to comment on the definition of complications. We completely agree that death should be reported on a per-patient basis (ie, the denominator). The authors stated that major and minor complications and side effects should be reported on the basis of the number of ablation sessions on a per-session basis. Moreover, they suggest specifying whether the denominator represents the number of sessions or the number of tumors. If we have to standardize terms in order to obtain a more accurate comparison of the results occurring with different ablation techniques (eg, percutaneous ethanol injection or radiofrequency or laser ablation), it would, in our opinion, be more appropriate to divide the number of complications by the number of ablated nodules (the sole common denominator).
This, in fact, is the real parameter that represents the goal of therapy for all ablative techniques, and to achieve it, we use different numbers of sessions and/or different numbers of ablations in different nodules (ie, diameter, site) depending on the method used. Only in this way can we compare the true incidence of complications by the use of different percutaneous ablation therapies.
Finally, when we have to compare the complications of image-guided ablation tumor techniques with those of other treatments that involve more than one hepatic nodule at the same time (eg, resection, chemoembolization, radiation therapy, or chemotherapy), the comparison should not be performed on the basis of the number of ablated nodules. In this situation, we have to compare the complications on a per-patient basis, where the denominator represents a cured patient in whom all the hepatic nodules have been ablated, regardless of the number of nodules, sessions, or treatment methods.
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,
Debra Ann Gervais, MD
,
Riccardo Lencioni, MD
,
David Sacks, MD|| and
Damian Dupuy, MD#
* Department of Radiology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215
Department of Radiology, Harvard Medical School, Brigham and Women's Hospital, Boston, Mass
Department of Radiology, GI/GU Division, Massachusetts General Hospital, Boston, Mass
Department of Radiology, University of Pisa, Pisa, Italy
|| Department of Radiology, The Reading Hospital and Medical Center, Reading, Pa
# Division of Ultrasound, Brown University-Rhode Island Hospital, Providence, RI
e-mail: sgoldber{at}caregroup.harvard.edu
The Technology Assessment Committee of the Society of Interventional Radiology and the authors of "Image-guided Tumor Ablation: Standardization of Terminology and Reporting Criteria" thank Drs Arienti and Pretolani for their thoughtful and productive comments regarding two points addressed in the standards document (1). As we noted in our article, we encourage continued direct dialogue and discussion about the committee's decisions through appropriate academic channels for this iterative and evolving project. As we have done for prior versions of this document, we acknowledge the constructive comments, will fully reevaluate the points raised, and will consider incorporating these and other suggestions in the next revision.
Drs Arienti and Pretolani contend that tract seeding is always a major complication, despite the recommendations in the standards document that "several complications, such as pneumothorax or tumor seeding, can be either a major or minor complication depending on severity" (1). After further discussion, we believe that our original contention is correct; applicator tract seeding should be classified on a case-by-case basis. Drs Arienti and Pretolani suggest that seeding always leads to a "true worsening of the patient's condition." However, we believe that this phrase is vague. The patient's "condition" could refer to the malignancy and the statement would imply that the survival was adversely affected. We believe that this is not necessarily the case. Most investigators subscribe to the notion that metastases do not "beget" other metastases. Furthermore, we contend that if the seeding is treated successfully, the overall condition should not be considered "worse."
Determining whether applicator tract seeding is an independent predictor of low survival rates would require a longitudinal study that shows that patients who experience this complication in fact do worse. We are unaware of such a study. The authors state that that there are more than 30 articles on this topic in the past 5 years, but they do not cite any specific references. Our best guess is that the 30 articles are reports describing cases or series in which seeding occurred. Yet, for most reports, it is difficult to ascertain whether a subsequent poor course is related to seeding or to unsuccessfully treated tumor elsewhere. Regardless, the fact that one can find 30 references with a MEDLINE search does not make a given complication major over minor.
We further respectfully disagree with the suggestion by Drs Arienti and Pretolani that "iatrogenic seeding is an upstaging of the disease even if the ectopic tumor nodule can be successfully treated by means of repeat ablation." If all disease is treated, there is no "upstaging." Accordingly, a subcutaneous nodule that is either successfully resected or ablated might be considered a minor complication, particularly if the patient's ultimate outcome (eg, survival) is not affected. Thus, in cases where distant disseminated disease or comorbid conditions such as end-stage liver disease are responsible for morbidity, mortality, and alteration in quality of life, the seeding is only a minor complication. We do agree, however, that the details of any treatment and outcome of the seeding, regardless of whether the seeding itself is reported as major or minor, be reported by investigators to provide the necessary information for future analyses.
We acknowledge that greater discussion and less consensus was achieved regarding a second aspect of the inquiry on seeding, specifically the veracity of our explanatory sentence: "For tumor seeding, this would depend on whether the ectopic tumor focus can be successfully ablated or otherwise treated." Nevertheless, the majority still favor classification of a solitary local or subcutaneous focus that can be treated with a repeat ablation procedure as a minor complication, as this can be likened to a situation of local tumor progression successfully managed by means of repeat ablation. Hence, we reiterate that at this point it should be left to the discretion of the authors of the report whether to describe this complication as major or minor (given that there were no life-threatening consequences). Regardless, we all agree that tract seeding that cannot be successfully treated and that has deleterious effects on patient outcome should be considered a major complication in most cases.
Fortunately, the issue of tract seeding may be less of an issue than intimated by Drs Arienti and Pretolani. Indeed, results of a large multicenter series place this complication at 0.7%, similar to other interventional procedures (2). Additionally, authors of several studies have reported methods for reducing this complication (2,3).
A second point raised by Drs Arienti and Pretolani relates to their suggestion that complication rates should be reported relative to the number of ablated nodules, not sessions. Here, the committee unanimously, respectfully disagrees with this proposal which, as Drs Arienti and Pretolani themselves point out, would have major limitations for cases where multiple tumors are treated or tumors are treated over multiple sessions (a situation that is quite common in many of our practices). By using the system proposed by Drs Arienti and Pretolani, artificial elevation of the complication rate will occur if a complication occurs when treating local tumor progression in the same nodule 3 months after a successful ablation. Likewise, artificial dilution of the complication rate would ensue if we divide the complication rate over five ablated tumors. Furthermore, the conventional notion that complications are expressed per procedure or session is fundamental and understood by all in medicine. It is standard for all interventional radiology procedures (including for chemoembolization [4]) and surgery. Deviating from this would confuse readers.
In conclusion, tumor seeding, even when abiding by the Society of Interventional Radiology definitions of major and minor complications (5), can be major or minor and is patient-specific. For the reasons expressed above, these and other complications should be expressed by using the traditional denominator of a per-session basis rather than a per-tumor basis. We again thank Drs Arienti and Pretolani for their suggestions. We further wish to assure them, as well others who have contacted us about "Image-guided Tumor Ablation: Standardization of Terminology and Reporting Criteria," that the document will be periodically altered over time and that their suggestions will be further discussed at that time.
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This article has been cited by other articles:
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  V. Arienti, S. Pretolani, C. M. Pacella, F. Magnolfi, B. Caspani, G. Francica, A. S. Megna, R. Regine, M. Sponza, E. Antico, et al. Complications of Laser Ablation for Hepatocellular Carcinoma: A Multicenter Study Radiology, March 1, 2008; 246(3): 947 - 955. [Abstract] [Full Text] [PDF]
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