Breast Cancer in Men: Similarities and Differences
Abstract & Commentary
Synopsis: Breast cancer is uncommon in men. In the current report, the NCI SEER database was examined to provide much needed epidemiological data on the similarities and differences of breast cancer in males and females. In general, men with breast cancer are older and present with more advanced disease. Yet, when matched for age and stage at presentation, overall survival is quite similar between men and women with this disease.
Source: Giordano SH, et al. Cancer. 2004;101:51-57.
Male breast cancer remains an uncommon disorder and data about clinical and biological features have, by necessity, been derived from relatively small clinical series. Furthermore, men with breast cancer are typically excluded from large clinical trials, and therefore any sex-specific feature with regard to treatment response has not been adequately addressed. To help fill in the gaps with regard to clinical and biological features of breast cancer and men, Giordano and colleagues utilized the National Cancer Institute (NCI) Surveillance, Epidemiology, and End Results (SEER) 1973-1998 database. This is a population-based cancer registry that has become the authoritative source of information concerning cancer incidence and survival in the United States. The areas included in the registry are the states of Connecticut, Hawaii, Iowa, New Mexico, and Utah, as well as the metropolitan areas of San Francisco, Oakland, Detroit, Seattle and Atlanta. Overall, the SEER database represents approximately 14% of the US population.
For the purpose of the current analysis, from the 2537 men and 383,146 women with breast cancer, on whom data was captured in SEER, age-adjusted incidence rates were calculated and clinical/biological features were compared. Over the years of the study, the incidence rates of male breast cancer increased significantly from 0.86 to 1.08 per 100,000 (P < 0.001). Men had a higher median age at diagnosis (P < 0.001) and were more likely to have lymph node involvement (P < 0.001), a more advanced stage at diagnosis (P < 0.001), and tumors that were positive for estrogen receptor (ER) (P < 0.001) and progesterone receptor (PR) (P < 0.001). In multivariate analysis, larger tumor size and lymph node involvement were associated with shortened survival. Tumor grade and ER/PR status did not appear to independently influence survival. Finally, the relative survival rates, by stage, were comparable for men and women.
Comment by William B. Ershler, MD
Breast cancer in men remains uncommon, but not rare. Most active medical oncologists have had some experience, as it remains that approximately 1% of all breast cancer occurs in men. Yet, it is a bit surprising that the sum total of our understanding has been derived from relatively small retrospective reviews. The current investigation of the SEER database reflects the best information to date on this topic. The data clarify features that are similar in male or female patients and those that are different. Furthermore, the analysis indicated a clearly rising incidence in male breast cancer (from 0.86 to 1.08 cases per 100,000 population over the 25 years that spanned 1973-1998).
When compared to women patients, men present with disease at a more advanced age (67 vs 62 years; P < 0.001), with larger tumors and more likely regional lymph node involvement. Overall, survival is worse for men, but when analyzed by age and stage this difference disappears. Histological features are also somewhat different for men, with a relative greater percentage of papillary histologies and a nearly absent number of patients with lobular pattern. Curiously, a higher percentage of men presented with ER positive tumors (approximately 90% vs 76% for women). Evaluation also revealed the relative survival rates, when adjusted for race, gender, age and stage, were actually quite comparable for males and females. This latter observation runs counter the commonly held notion that survival was worse for men.1
By examining a large database, the authors have contributed a solid reference on the epidemiology of breast cancer in men, with a highlight on the differences with the same disease in women. What can be said with confidence is that the disease appears later and at a more advanced stage in men, and that its incidence is increasing. Yet, there are also differences in histology and hormone receptor positivity, implying the presence of poorly understood biological differences. It would take global efforts to construct clinical trials directed at determining optimal management of breast cancer in men, and short of that, clinical oncologists are likely to fall back to the evidence obtained from clinical trials in women.
1. Scott-Conner CE, et al. Surgery. 1999;126:775-780.
William B. Ershler, MD, INOVA Fairfax Hospital Cancer Center, Fairfax, VA; Director, Institute for Advanced Studies in Aging, Washington, DC, is Editor of Clinical Oncology Alert.