Time to Remove the Subspecialty Blinders: Breast Cancer Does Not Exist in Isolation
Authors: S. H. Giordano, G. N. Hortobagyi
Journal: JNCI Journal of the National Cancer Institute (2008)

As oncologists, we focus on treating cancer and preventing cancerrelated deaths. However, how aggressively are our patients treated for non – cancer-related medical problems? This question should be of great importance to oncologists, particularly those who treat breast cancer patients. The survival rates for breast cancer have improved over the past several decades, likely because of an increase in screening and improvements in therapy ( 1 , 2 ). As deaths from breast cancer fall and the population ages, breast cancer patients are increasingly likely to die of other illnesses. Thus, appropriate treatment of medical conditions other than breast cancer is critical for our patients’ overall health. Understanding the risk of death from breast cancer in the context of the competing risk of death from other causes is also essential when estimating the risk and benefits of therapy for breast cancer patients. For instance, if a patient has a limited life expectancy because she has cardiovascular disease, systemic adjuvant therapies for breast cancer are unlikely to impact survival. In a patient who is 70 years old and has a 2-cm estrogen receptor – positive tumor and four positive lymph nodes, adjuvant hormonal therapy is associated with a 32% relative reduction in risk of death from breast cancer ( 3 ). If she is in perfect health, the relative risk reduction would translate to a 10% absolute survival benefit at 10 years. However, if she has a major comorbid illness, the absolute survival benefit would be reduced to less than 1%. In this issue of the Journal, Chapman et al. ( 4 ) have examined the competing risks of death in a cohort of patients treated in MA.17, a randomized trial that evaluated extended adjuvant therapy with letrozole vs placebo. Overall, the majority of deaths in this postmenopausal patient population were from causes other than breast cancer; only 40% of the deaths were attributable to breast cancer. The results were more striking for older women: non – breast cancer deaths accounted for 72% of the deaths among women who were aged 70 years or older vs 48% of the deaths among women who were younger than 70 years. As would be expected, women with a baseline diagnosis of cardiovascular disease were statistically signifi cantly more likely to die from causes other than breast cancer. These fi ndings highlight our success in treating women with breast cancer because the minority of deaths were from breast cancer. These results also provide an opportunity to refl ect on comorbidities in breast cancer patients, some of which may be attributed to cancer therapy. One potential concern about the study by Chapman et al. ( 4 ) is that the population of patients in MA.17 was not representative of all breast cancer patients. The MA.17 trial enrolled patients with estrogen receptor – positive or unknown tumors who had remained free of disease after approximately 5 years of adjuvant endocrine ther apy with tamoxifen. Thus, the patients selected had hormonally sensitive tumors and a good prognosis. However, the data from the Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial are very similar to the MA.17 data despite treating patients in the adjuvant rather than “extended adjuvant” setting ( 5 ). Sixty percent of all