CHICAGO -- Breast cancer in men is usually detected when the tumors are bigger, have spread and may be more aggressive, compared to diagnosis of the disease in women, concludes the largest study ever conducted of male breast cancer. The findings, presented at the annual meeting of the American Society of Clinical Oncology, suggest both that breast cancer in men may have some important biological differences from the female disease, and that men are seemingly less aware than they should be that they can develop breast cancer.
"Male breast cancer is rare, accounting for only about one percent of all breast cancer, or about 1,600 new cases in the United States in 2002, but men should be alert to the possibility that the disease could affect them," says the study's lead investigator, Sharon Giordano, M.D., of The University of Texas M. D. Anderson Cancer Center.
"It's perhaps ironic that tumors in men are easier to feel than they are in women, yet the disease is being discovered at a later stage in men than in women," says Giordano, assistant professor in the Department of Breast Medical Oncology.
One reason for such a late diagnosis may be that men assume they are experiencing a benign condition called gynecomastia, or atypical growth of breast tissue that affects about a third of males at some point in their lives, she says. The condition, common in adolescent boys, can come and go over a man's lifetime, and "men may think new growth of breast tissue is just another occurrence of this condition," Giordano says.
Because breast cancer in men is rare, little is known about how it differs from breast cancer in women and how it should be best treated. To assess dissimilarity, Giordano and her colleagues used information from a National Cancer Institute database called SEER (Surveillance, Epidemiology, and End Results), which is the authoritative source of information on cancer incidence and survival in the United States.
They analyzed SEER data from 1973 through 1998 on 2,524 cases of male breast cancer and 380,856 cases of female breast cancer. Compared to female patients, the investigators found that male patients were significantly older when diagnosed, more likely to have later stage disease, had more spread of the cancer to their lymph nodes, and were more likely to have ductal and papillary cancers.
Yet despite these differences, five-year, 10-year and median survival were not different between men and women, investigators say.
Also of interest to the researchers was the finding that male patients are more likely than female patients to have estrogen receptor-positive tumors. "We are not sure why this is so, but it may indicate some important differences in tumor biology," she says. "In addition, this implies that use of tamoxifen in men may be as beneficial as it is to many women," says Giordano.
"Now that we have a clearer understanding of the biology of breast cancer in men, further research is needed to determine the optimal treatment for men," she says.
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