IRVINE, Calif. -- Male breast cancer is comparatively rare, but its diagnosis carries an elevated risk of second primaries, found epidemiologists here.
IRVINE, Calif., Jan. 25 -- Male breast cancer is comparatively rare, but its diagnosis carries an elevated risk of second primaries, found epidemiologists here.
Men with the primary diagnosis have a higher relative risk of developing a second breast cancer as well as an increased risk for melanoma and stomach cancer, epidemiologist Hoda Anton-Culver, Ph.D., of the University of California at Irvine reported.
Moreover, the risk increased over time and appeared to be greatest among younger men, said Dr. Anton-Culver in Breast Cancer Research, an online open-access journal.
Among the 1,926 men in California diagnosed over six years with breast cancer, 11.5% developed a second primary, Dr. Anton-Culver said and colleagues. The American Cancer Society estimated that in 2007 some 2,030 new cases of invasive breast cancer would be diagnosed among men in the United States.
The standardized incidence ratio for any second primary was 1.16 (95% confidence interval 1.01-1.32), but for a second breast cancer the risk was more than 50 times greater than expected in general population (SIR=52.12, 95% CI 31.83-80.49).
For melanoma the relative risk was about three times greater than expected (SIR=2.98, 95% CI 1.63-5.00) and for stomach cancer it was about twice the expected rate (SIR=2.11, 95% CI 1.01-3.88), Dr. Anton-Culver said.
After five years the excess risk of second malignancy was threefold in men younger than 60 at diagnosis and twofold in men 60 to 69.
The authors recommended that male breast cancer patients should be "monitored carefully for the occurrence of second primary cancers, especially a second primary breast cancer."
The authors identified the patients from data collected by the California Cancer Registry from 1988 through 2003. The 1,926 men were all younger than 85 at the time of breast cancer diagnosis.
The risk of second malignancies was greatest among non-Hispanic whites, who had a 19% increase in risk and more than a 2.5-fold increase in risk of stomach cancer.
The authors said that with the exception of a second breast cancer there was "no statistical association of subsequent cancer risk with prior hormone therapy, radiation therapy, or chemotherapy."
There was an increased SIR for second primary breast cancer in patients with and without prior hormone therapy and chemotherapy, but the authors said this finding was most probably "related to the rarity of breast cancer in men, which causes each observed case to contribute a substantial portion to the risk estimate."
Dr. Anton-Culver and colleagues said that about 15% of all male breast cancers have a BRCA-2 susceptibility mutation. In males, tumors related to BRCA mutations also include melanoma, stomach, prostate, colon, and pancreatic cancers.
The researchers acknowledged that the study was limited by its retrospective design and by the unavailability of potentially confounding data, including family history, genetic predisposition, and environmental exposures.
Moreover, they note the potential for a cohort effect since as cancer survivors the men were more likely to have frequent follow-up, which increased the likelihood of detecting a second cancer.