Mikael Hartman, MD
New data show that while men are diagnosed with breast cancer at a mere fraction of the rate of women, they tend to have more advanced disease at the time of diagnosis. However, the results, from an international population-based study that compared male and female breast cancer using information from combined cancer registries, also indicate that men are less likely to die of the disease.
Mikael Hartman, MD, with the National University Hospital of Singapore, and colleagues examined data in a total of 459,846 women and 2665 men who had been diagnosed with breast cancer in Denmark, Finland, Norway, Singapore, Sweden, and Geneva, Switzerland, over the last 40 years. In the 6 regions that contributed patients to the analysis, it is required by law for clinicians, pathologists, and healthcare institutions to notify the cancer registry of any incident cancer.
Results showed that male breast cancers accounted for only 0.6% of all breast cancers, and the percentage was similar for all 6 regions. The overall age-standardized incidence rates were 0.4 per 100,000 person-years in men and 66.7 per 100,000 person-years in women.
Women were diagnosed with breast cancer at a younger median age than men (61.7 y vs 69.6 y, respectively; P
For patients in whom staging information was available, 41% of men and 44% of women were classified as having localized disease. Eleven percent of men and 6% of women had distant disease (P
Male patients also had a worse 5-year relative survival ratio than women (0.72 [95% CI, 0.70-0.75] vs 0.78 [95% CI, 0.78-0.78], respectively); this corresponds to a relative excess risk (RER) of 1.27 (95% CI, 1.13-1.42). The lower “observed survival” in male patients with breast cancer is primarily due to their more advanced stage and higher age at the time of diagnosis and less standard locoregional treatment, according to the authors.
However, after controlling for life expectancy, age and year of diagnosis, stage, and treatment, male patients with breast cancer had a survival benefit compared with women (RER, 0.78; 95% CI, 0.62-0.97) .
Hartman and colleagues cited as an inevitable shortcoming the time frame of nearly 40 years during which there were “improvements in diagnosis performance and the increased diagnostic intensity in women,” which improved the pick-up of small, frequently indolent cancers. Other potential study liabilities include differences in staging systems among registries and limited data, not only on tumor characteristics such as grade and estrogen receptor status age, but also on systemic treatment.
They emphasized, however, that their study is notable in that, unlike earlier studies comparing outcome in male and female breast cancer, their analysis accounted for sex differences in life expectancy by examining relative survival and RER.
Miao H, Verkooijen HM, Chia KS, et al. Incidence and outcome of male breast cancer: an international population-based study [published online ahead of print October 3, 2011]. J Clin Oncol. 2011;29(33): 4381-4386.