Several Factors Linked to Outcomes of Male Breast Cancer

By Reuters Staff

October 13, 2019

NEW YORK (Reuters Health) - Several factors are independently associated with better or worse overall survival in men with breast cancer, according to new findings.

Male breast cancer accounts for only 1% of all breast cancer cases, but its incidence appears to be rising. Compared with female breast cancer, male breast cancer tends to present at an older age, with more frequent lymph node metastases and a higher percentage of estrogen-receptor-positive (ER+) tumors, researchers note in Cancer, online October 7.

Unlike female breast cancer, male breast cancer is more likely to occur within the setting of a BRCA2 mutation rather than a BRCA1 mutation, and a low androgen state is a known risk factor for male breast cancer, Dr. Kathryn J. Ruddy and colleagues from Mayo Clinic, in Rochester, Minnesota, point out.

The team used data from the National Cancer Data Base on more than 10,000 male patients diagnosed with TNM stage I to stage III invasive ductal carcinoma or invasive lobular carcinoma between 2004 and 2014 to describe treatment patterns and prognostic factors of male breast cancer in the United States.

Most men (about 90%) had ER+ tumors, and only 5.5% of those with available data had triple-negative breast cancer. More men were diagnosed with stage II disease (43.4%) than with stage I disease (37.9%).

Overall, 71.3% of patients underwent total mastectomy and 23.7% had breast-conserving surgery (BCS); 6.1% underwent contralateral prophylactic mastectomy.

Total mastectomy rates increased by 0.8% annually, while BCS rates decreased by 2.2% annually.

Nearly 40% of men received some form of adjuvant radiotherapy, including 70.2% of those who underwent BCS and 29.2% of those who underwent a mastectomy. A similar fraction (44.5%) received chemotherapy, and 62.3% of those with ER+ tumors received adjuvant endocrine therapy.

The percentage of men who underwent radiotherapy after BCS increased 1.6% annually, whereas there was no significant change in the overall chemotherapy rate between 2004 and 2014.

The median overall survival was 12.1 years, with estimated five-year overall survival of 79.1%, values that did not change significantly between 2004 and 2014.

In multivariable analysis, factors independently associated with worse overall survival included older age, black race, higher Charlson Comorbidity Index, high tumor grade, high tumor and lymph node classifications, and undergoing total mastectomy.

Independent predictors of better overall survival included residing in a high-income area, having a progesterone-receptor-positive tumor, and receipt of chemotherapy, radiotherapy, or endocrine therapy.

"The results of the current study highlight unique practice patterns and factors associated with prognosis in patients with male breast cancer, furthering our understanding of the treatment and prognosis of male breast cancer and identifying unanswered questions for future research," the authors conclude.

Dr. Reddy did not respond to a request for comments.

SOURCE: https://bit.ly/2M3QV8P

Cancer 2019.

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