Male breast cancer: a population-based comparison with female breast cancer

Abstract

Purpose: Because of its rarity, male breast cancer is often compared with female breast cancer.

Patients and methods: To compare and contrast male and female breast cancers, we obtained case and population data from the National Cancer Institute's Surveillance, Epidemiology, and End Results program for breast cancers diagnosed from 1973 through 2005. Standard descriptive epidemiology was supplemented with age-period-cohort models and breast cancer survival analyses.

Results: Of all breast cancers, men with breast cancer make up less than 1%. Male compared with female breast cancers occurred later in life with higher stage, lower grade, and more estrogen receptor-positive tumors. Recent breast cancer incidence and mortality rates declined over time for men and women, but these trends were greater for women than for men. Comparing patients diagnosed from 1996 through 2005 versus 1976 through 1985, and adjusting for age, stage, and grade, cause-specific hazard rates for breast cancer death declined by 28% among men (P = .03) and by 42% among women (P approximately 0).

Conclusion: There were three intriguing results. Age-specific incidence patterns showed that the biology of male breast cancer resembled that of late-onset female breast cancer. Similar breast cancer incidence trends among men and women suggested that there are common breast cancer risk factors that affect both sexes, especially estrogen receptor-positive breast cancer. Finally, breast cancer mortality and survival rates have improved significantly over time for both male and female breast cancer, but progress for men has lagged behind that for women.

Fig 1.

Age-standardized rates (ASRs) with the estimated annual percentage changes (EAPCs) in the ASR for male and female (A) breast cancer incidence rates and (B) mortality rates. (A) ASR for incidence (in situ + invasive). From 1974 to 2005, EAPCs were 1.30% per year (95% CI, 0.97% to 1.62%) for women and 0.86% per year (95% CI, 0.47% to 1.25%) for men. ASRs peaked in 1999 at 165 per 100,000 for women, after which the EAPC fell at a rate of −1.85% per year (95% CI, −2.63% to −1.07%). ASRs peaked in 2000 at 1.24 per 100,000 for men, after which the EAPC was −0.46% per year (95% CI, −5.45% to 5.25%). (B) ASR for mortality: From 1974 through 2005, EAPCs were −1.16% per year (95% CI, −1.41% to −0.91%) for women and −0.27% per year (95% CI, −0.77% to 0.23%) for men.

Fig 2.

Age-specific incidence rate trends with the net drifts expressed as an annual percentage change for male (A) and female (B) breast cancer. Reference line is drawn at the year 2000 where incidence rates peaked for men and women. (A) Annual percentage change in the net drifts for male breast cancer incidence rates was 1.19% per year (95% CI, 0.54% to 1.83%). (B) Annual percentage change in the net drifts for female breast cancer incidence rates was 1.48% per year (95% CI, 1.34% to 1.63%).

Fig 3.

Age-specific mortality rate trends with the net drifts expressed as an annual percentage change for male (A) and female (B) breast cancer. (A) Annual percentage change in the net drifts for male breast cancer mortality rates was −0.58% per year (95% CI, −1.27% to 0.11%). (B) Annual percentage change in the net drifts for female breast cancer mortality rates was −1.28% per year (95% CI, −1.34% to −1.22%).

Fig 4.

Age-period-cohort fitted age-specific curves (A and C) and age-specific rate ratios (B and D) for male and female breast cancers. (A) The age-specific incidence rates among women increased rapidly until age 50 years and then paused, after which incidence rates rose at a slower pace. The age-specific inflection near age 50 years has been termed Clemmesen's hook. Clemmesen's hook has been attributed to menopause and is absent among men. Age-specific incidence rates for men rose steadily (linearly or monotonically) with aging and lacked a Clemmesen's hook. (B) Male-to-female age-specific incidence rate ratio narrowed steadily with advancing age. (C) Age-specific mortality rates among women increased rapidly until age 50 years and then paused near Clemmesen's hook, after which mortality rates rose at a slower pace. Age-specific mortality rates for men rose steadily (linearly or monotonically) with aging. (D) Male-to-female age-specific mortality rate ratio narrowed steadily with advancing age.

Fig 5.

Actuarial breast cancer–specific free survival (A and B) and hazard rates for breast cancer death (C and D) for male and female breast cancers, with 95% CIs. Hazard ratios for breast cancer death were adjusted for age at diagnosis, Surveillance, Epidemiology, and End Results (SEER) historic stage A (local, regional, or distant), and tumor grade (low and high). (A) Actuarial breast cancer–specific free survival for male breast cancer from 1976 to 1985, 1986 to 1995, and 1996 to 2005. (B) Actuarial breast cancer–specific free survival for female breast cancer from 1976 to 1985, 1986 to 1995, and 1996 to 2005. (C) Hazard rate ratios for male breast cancer deaths. Hazard rates during 1986 to 1995 and 1996 to 2005 were compared with a baseline hazard rate during 1976 to 1985. (D) Hazard rate ratios for female breast cancer deaths. Hazard rates during 1986 to 1995 and 1996 to 2005 were compared with a baseline hazard rate during 1976 to 1985.