This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Save to my personal folders Download to citation manager Rights & Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Vergouwe, Y. Articles by Steyerberg, E. W. Search for Related Content PubMed PubMed Citation Articles by Vergouwe, Y. Articles by Steyerberg, E. W. Social Bookmarking                            What's this?

Minimal Residual Tumor Masses in Nonseminomatous Testicular Cancer: Surgery or Surveillance?

Center of Clinical Decision Sciences, Department of Public Health, Erasmus MC, Rotterdam, the Netherlands

To the Editor:

The report of Oldenberg et al¹ is undoubtedly an important contribution to the debate on the resection of small residual masses of nonseminomatous testicular cancer. This is an area in which decision making is tough.

In a group of 87 patients with small postchemotherapy retroperitoneal masses ( 20 mm), 29 patients (33%) had masses containing vital tumor (ie, mature teratoma or viable cancer as opposed to necrosis). According to the authors, their data did not show a clear relationship between previously identified powerful predictors as combined in a "necrosis score"² and the histology of the residual masses. They concluded that surgery after chemotherapy is necessary in all patients with residual masses 20 mm.

It is clear that small residual masses, which are often considered as normal, may contain vital tumor.^1,2 However, we disagree that valid predictions on the histology of small residual masses are not possible, and that surgery is necessary for all patients. The methods to study the validity of the necrosis score were incorrect, which led to a wrong conclusion.

First, the studied necrosis score seems to be based on wrong calculations. Normal levels of postchemotherapy lactate dehydrogenase (LDH) were assigned a positive score, whereas elevated levels of LDH should actually be given a positive score.² This means that one of the five predictors was scored inversely, which dilutes the relationship with the histology of the residual mass. Second, the small sample size, with only 29 patients having residual vital tumor, does not provide sufficient statistical power to study the validity of the score. Hence, the study addresses a question that cannot be answered with the presented data. Third, a ² test with 5 degrees of freedom was used where more appropriate methods are available, such as a ² test for trend with one degree of freedom, or tests that compare observed outcomes with those expected.³ As can be calculated from Table 3 in the Oldenberg et al study,¹ the percentages of patients with necrotic masses showed a clear trend, even over the incorrectly calculated score (25%, 55%, 64%, 69%, 75%, and 100% for the scores 0 to 5, respectively).

We have shown in different studies that combinations of predictors of residual mass histology give accurate predictions, also in masses 20 mm.^4-6 These studies included 85 patients with masses 20 mm from the Norwegian Radium Hospital.⁷ Therefore, the central point of the discussion should be, "what are sufficiently high predictions to guide decisions of resection omission?" This is something for physicians and patients to discuss, based on the risks of missing vital tumor against the burden of unnecessary surgery.^8,9 To be on the safe side, every patient should undergo surgery after chemotherapy, including all patients with small or normal masses. This implies a threshold value of 100% for the probability of necrosis. However, the risks of missing vital tumor are probably not so large, as reflected by the rather low relapse rates in these patients.⁶ Therefore, other experts deem surgery unnecessary for normal masses (a threshold value of 0%).¹⁰ We would propose an intermediate policy (a threshold value between 0% and 100%, eg, 70%), that is, surgery for small or normal masses, if the probability of necrosis is low (eg, 70%) according to previously developed and validated statistical models, and close follow-up, if the probability is high (> 70%).

Authors' Disclosures of Potential Conflicts of Interest

The authors indicated no potential conflicts of interest.

REFERENCES

1. Oldenburg J, Alfsen GC, Lien HH, et al: Postchemotherapy retroperitoneal surgery remains necessary in patients with nonseminomatous testicular cancer and minimal residual tumor masses. J Clin Oncol 21:3310-3317, 2003[Abstract/Free Full Text]

2. Steyerberg E, Keizer H, Fosså S, et al: Resection of residual retroperitoneal masses in testicular cancer: Evaluation and improvement of selection criteria. Br J Cancer 74:1492-1498, 1996[Medline]

3. Vergouwe Y, Steyerberg EW, Eijkemans MJ, et al: Validity of prognostic models: When is a model clinically useful? Semin Urol Oncol 20:96-107, 2002[CrossRef][Medline]

4. Steyerberg E, Gerl A, Fosså S, et al: Validity of predictions of residual retroperitoneal mass histology in nonseminomatous testicular cancer. J Clin Oncol 16:269-274, 1998[Abstract/Free Full Text]

5. Vergouwe Y, Steyerberg E, Foster R, et al: Validation of a prediction model and its predictors for the histology of residual masses in nonseminomatous testicular cancer. J Urol 165:84-88, 2001[CrossRef][Medline]

6. Vergouwe Y, Steyerberg E, de Wit R, et al: External validity of a prediction rule for residual mass histology in testicular cancer: An evaluation for good prognosis patients. Br J Cancer 88:843-847, 2003[CrossRef][Medline]

7. Fosså S, Qvist H, Stenwig A, et al: Is postchemotherapy retroperitoneal surgery necessary in patients with nonseminomatous testicular cancer and minimal residual tumor masses? J Clin Oncol 10:569-573, 1992[Abstract/Free Full Text]

8. Steyerberg E, Marshall P, Keizer H, et al: Resection of small, residual retroperitoneal masses after chemotherapy for nonseminomatous testicular cancer: A decision analysis. Cancer 85:1331-1341, 1999[CrossRef][Medline]

9. Charles CA, Whelan T, Gafni A, et al: Shared treatment decision making: What does it mean to physicians? J Clin Oncol 21:932-936, 2003[Abstract/Free Full Text]

10. Einhorn LH: In reply: Postchemotherapy surgery in nonseminoma. J Clin Oncol 15:3166, 1997[Medline]

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Save to my personal folders Download to citation manager Rights & Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Vergouwe, Y. Articles by Steyerberg, E. W. Search for Related Content PubMed PubMed Citation Articles by Vergouwe, Y. Articles by Steyerberg, E. W. Social Bookmarking                            What's this?