A study of the molecular and genomic features of breast cancer in men, compared with those in women, highlights the prognostic value of a 21-gene breast recurrence score in both sexes, investigators say.
Men and women with estrogen receptor (ER)–positive breast cancer who had recurrence scores (RS) of 0 to 30 on the 21-gene assay (Oncotype DX) had excellent breast cancer–specific survival rates, which suggests that such patients could be spared from more aggressive treatments, such as chemotherapy, according to Suleiman Alfred Massarweh, MD, of Stanford (Calif.) University and his colleagues.
“Future adjuvant trials in ER-positive breast cancer may need to focus on targeting endocrine resistance in those patients with RS greater than 31 and may need to consider the weight of competing mortality risk when investigating the value of any additional treatment beyond endocrine therapy,” they wrote in the Journal of Clinical Oncology.
In 2016, an estimated 2,600 men were diagnosed with breast cancer in the United States.
“Approximately 95% of breast cancers diagnosed in men express the estrogen receptor and progesterone receptor (PR), which is a higher percentage than in women and suggests a key role for ER in the biology of breast cancer in men,” the investigators noted.
Although treatment of men with breast cancer has traditionally been extrapolated from treatment of women with breast cancer, genomic studies have suggested some key differences, the investigators noted, citing a study of the genomic landscape of male breast cancers presented at the 2014 San Antonio Breast Cancer Symposium.
In that study, investigators from the Memorial Sloan Kettering Cancer Center in New York and other institutions found that all male breast cancers in their sample of 64 patients were ER+ and human epidermal growth factor receptor 2 (HER2)–negative, predominantly of the luminal B subtype, and that the genetic alterations seen in male breast cancers frequently target DNA-repair fibroblast growth factor pathways. However, the pathways that are known to drive luminal cancers when mutated in women are seen less often among men, said Salvatore Piscuoglio, PhD, then a research fellow at MSKCC.