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Primary Disease Resection in Metastatic Breast Cancer Improves Survival

University of Wisconsin Comprehensive Cancer Center, Madison, WI

To the Editor:

We read with interest the article by Rapiti et al¹ entitled, "Complete Excision of Primary Breast Tumor Improves Survival of Patients With Metastatic Breast Cancer at Diagnosis." In this retrospective observational study, the authors report a 50% reduction in breast cancer mortality in women who underwent surgical removal of the primary breast tumor. The survival advantage appeared to be significant only in women who had negative surgical margins. Furthermore, the effect of surgery on mortality was the greatest in the subgroup of patients with bone-only metastasis.

From these results the authors concluded that "removal of the primary tumor could be viewed as part of a multimodal strategy to prevent additional metastasization of cancer cells." The implication is that eradicating the primary tumor confers a survival advantage by way of preventing the occurrence of further metastatic disease. However, our review of the results suggests that the survival benefit is not from prevention of new metastasis. We noted the survival curves presented in Figure 1 begin to separate immediately, favoring the group that had surgery with negative margins. Given the doubling time of breast cancer cells, it would take several years for a small number of metastatic cells to grow into a clinically apparent tumor. We therefore conclude that the difference in survival must be attributable to another mechanism that takes effect immediately after surgery. Alternative hypotheses might include endocrine or cytokine-mediated effects that ultimately modify the behavior of the tumor cells in the metastatic sites.

It is possible that at least some of the difference in survival is due to confounding factors. For one thing, the authors did report that 28 patients died within 30 days of diagnosis—these patients presumably would have been too sick to have surgery or died before they had the chance. When these patients are excluded, the survival benefit for the surgery group is no longer statistically significant. Although the authors did adjust for many potential confounders, there may be other significant variables, such as comorbidities.

Despite the inherent limitations of this study, the apparent improvement in survival for the patients with bone-only metastasis is undoubtedly impressive, and worthy of further investigation.

AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST

The authors indicated no potential conflicts of interest.

REFERENCES

1. Rapiti E, Verkooijen HM, Vlastos G, et al: Complete excision of primary breast tumor improves survival of patients with metastatic breast cancer at diagnosis. J Clin Oncol 24:2743-2749, 2006[Abstract/Free Full Text]

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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 Choi, B. S. Articles by Robins, H. I. Search for Related Content PubMed PubMed Citation Articles by Choi, B. S. Articles by Robins, H. I. Social Bookmarking                            What's this?