Breast Cancer: To Treat or Not to Treat

I was interviewed this past week on a study to be published in the New England Journal of Medicine. This study was based on an analysis of women treated in Denmark who had undergone surgery for breast cancer in whom either isolated tumor cells (ITC) were found in lymph nodes (technically, node-negative) and women in whom microscopic metastatic disease (N1mic) was found (technically, node-positive). The authors showed that while the overall 5-year axillary recurrence rate was low, less than 2% of the population which included over 2500 women), the 5-year disease free survival (5yDFS) was signficantly shorter in women with any evidence of cancer in the lymph nodes. In women with node-negative disease the 5yDFS was 86% but in those with ITC it was 77% and in those with N1mic it was 76%. Of more interest was the finding that adjuvant systemic therapy reduced the risk of recurrence by 33% in women with ITC and by 50% in women with N1mic.

In the interview I suggested that this study questioned the dogma that ITC were nothing that warranted agressive treatment and would lead oncologists to question the value of chemotherapy, or in fact, to treat even the smallest amount of disease in the node as a node-positive patient. However, my friend and colleague, Michael Linver, also interviewed, suggested that it would raise the concern that more women would be subjected to toxic treatment for very little gain.

In truth, the decision to use adjuvant chemotherapy for breast cancer has become more and more personalized, and not one factor is able to distinguish those who should get chemotherapy and those who should not. As important as the status of the lymph nodes is what the tumor itself looks like. Large tumors, high-grade cancers, hormone receptors, and even HER-2/neu status are all used to determine which patients "should" undergo chemotherapy- and these decisions may be made independent of the nodal status. Afterall, a woman whose tumor is 2.5 inches wide, ER-negative, would still be recommended for chemotherapy on the size and hormone receptor status alone; negative, ITC, or N1mic would not dissuade my recommendation in such a case. Even more than histologic and receptor status, we are going in to a changing world of breast oncology. Genomics has introduced us in to a new lexicon of tumor characterization where gene expression defines the tumor type, not histology. Hence, we now speak of luminal and basaloid tumors, both of which carry their own prognostic indications.

So, while the study is interesting and inserts more controversy and thought in to the question of who should get chemotherapy, in reality the discussion has already taken steps beyond this. We now have the capacity to look at a tumor's own genes, and this information will probably be the most powerful information a medical oncologist can rely on when counselling a patient with newly diagnosed breast cancer.

Here is a link to the article, which appeared yesterday in The Wall Street Journal: http://online.wsj.com/article/SB10001424052970203496804574346624109995500.html.