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In Reply

Massachusetts General Hospital Cancer Center, Boston, MA

As we emphasized in our article,¹ the data we present are observational and the criticism of the writer applies to all such nonrandomized studies. The approach proposed is interesting, but cannot be applied to our study since the decision to allow patients to switch was made in October 2003 and some of the patients would be unavailable and many would be unable to accurately recall their state of mind when the study was unblinded.

Knowing that self-selection was likely to have occurred, we made the best statistical adjustments possible for prognostic factors known to influence breast cancer recurrence. As indicated in our article, the women electing to take letrozole appeared, not surprisingly, to have a higher risk of breast cancer recurrence. On this basis, if the treatment had had no effect, this group should have had a higher frequency of such recurrences. It remains possible that there may have been unmeasured confounding factors that we could not adjust for, however, the most likely explanation for the fact that the results were so positive in a direction contrary to that predicted, is that taking letrozole was beneficial.

Thus, although we recognize the limitations of our analysis as outlined in our discussion section, until a future clinical trial addresses the question specifically for the many women who have completed prior 5 years of adjuvant tamoxifen, it provides the best information available to patients and clinicians facing treatment decisions in the clinic.

AUTHOR'S DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST

Although all authors completed the disclosure declaration, the following author(s) indicated a financial or other interest that is relevant to the subject matter under consideration in this article. Certain relationships marked with a "U" are those for which no compensation was received; those relationships marked with a "C" were compensated. For a detailed description of the disclosure categories, or for more information about ASCO's conflict of interest policy, please refer to the Author Disclosure Declaration and the Disclosures of Potential Conflicts of Interest section in Information for Contributors.

Employment or Leadership Position: None Consultant or Advisory Role: None Stock Ownership: None Honoraria: Paul E. Goss, Novartis, AstraZeneca, Pfizer Research Funding: None Expert Testimony: None Other Remuneration: None

REFERENCE

1. Goss PE, Ingle JN, Pater JL, et al: Late extended adjuvant treatment with letrozole improves outcome in women with early-stage breast cancer who complete 5 years of tamoxifen. J Clin Oncol 26:1948-1955, 2008[Abstract/Free Full Text]

Related Correspondence

• Method to Test Whether Late Extended Letrozole, Rather Than Self- Selection, Improves the Outcome in Patients With Breast Cancer Who Have Completed 5 Years of Tamoxifen
  Jayant S. Vaidya
  JCO 2008 26: 3291 [Full Text]

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