SAN ANTONIO — Results from the largest series of male breast cancer cases ever studied showed that there was significant improvement in overall survival for male breast cancer patients over the duration of the study, but the improvement was not as good as has been seen for female breast cancer, according to research presented today at the 2014 San Antonio Breast Cancer Symposium, held Dec. 9–13.
“Although we saw a significant improvement in overall survival for male breast cancer patients over time, the prognosis for men with breast cancer has not been improving as much as for women with the disease,” said Fatima Cardoso, MD, director of the breast unit at the Champalimaud Cancer Center in Lisbon, Portugal. “This is largely because male breast cancer is a rare disease—it accounts for just 1 percent of breast cancers—and we know very little about its biology and how best to treat patients.
“Our results provide new insight into the clinical and biological characteristics of breast cancer in men, and show that they are not the same as those previously reported for breast cancer in women,” continued Cardoso. “Our results tend to show that men diagnosed with breast cancer are not well managed in the clinic. For example, even though most male breast cancers are ER-positive, we found that only 77 percent of patients received endocrine therapy like tamoxifen. We also found that even though 56 percent of male breast cancers are diagnosed when the tumors are very small, only 4 percent of patients had breast-conserving surgery; most had a mastectomy, which significantly impacted their quality of life.”
Tumor analyses to determine the biological characteristics of male breast cancer showed that 92 percent were positive for the estrogen receptor (ER), 5 percent were positive for HER2, and 1 percent were triple-negative. In women, approximately 70 percent of breast cancers are ER-positive, 20 percent are HER2-positive, and 10 to 15 percent are triple-negative.
Cardoso is part of a global network of researchers that includes investigators from all the major breast cancer consortia in Europe and North America. The first goal of the Male Breast Cancer International Program was to analyze the largest series of male breast cancer cases ever studied.
Cardoso and her colleagues enrolled in the study 1,822 men with breast cancer treated between 1990 and 2010 at 23 centers in nine countries. Clinical data for the patients were all analyzed at the European Organization for Research and Treatment of Cancer headquarters and tumor samples were analyzed at three locations—two in Europe and one in the United States. According to Cardoso, it was very important that the tumor samples be analyzed in central locations using the same protocols so that variation in analyses could be minimized.
“We are continuing to analyze the tumor samples that we collected during this first part of the project,” said Cardoso. “But we have also begun part two, which is the prospective register of all men diagnosed with breast cancer in many European, Latin American, and North American countries during a two-year period. This will allow the collection of a current series of these patients and assert the ability of the network to run clinical trials in this rare disease. We also hope to soon begin part three of the project, which will be a clinical trial to test a potential new treatment option for men with breast cancer.”
Funding for the study was provided by the Breast Cancer Research Foundation, European Breast Cancer Conference Council, Pink Ribbon NL, and Bröstcancerföreningarnas Riksorganisation (The Swedish Breast Cancer Association). Cardoso acts as a consultant or advisory board member for Astellas; AstraZeneca; Celgene; Daiichi-Sankyo; Eisai; GE Oncology; Genentech; GlaxoSmithKline PLC; Merck, Sharp, and Dohme; Merus B.V.; Novartis; Pfizer; Roche; and Sanofi, and has been on the speakers bureau for Prime Oncology.
Sharon H. Giordano, MD, MPH, chair of the Department of Health Services Research at The University of Texas MD Anderson Cancer Center in Houston, is the co-principal investigator of the study with Cardoso. The tumor samples were analyzed in the laboratories of John M. S. Bartlett, PhD, professor of molecular pathology at Edinburgh University, United Kingdom; Carolien H. M. van Deurzen, MD, at the Erasmus Medical Center in Rotterdam, the Netherlands; and Peggy L. Porter, MD, a member of the Human Biology and Public Health Sciences Divisions at the Fred Hutchinson Cancer Research Center in Seattle.