[5] However, MBC appears to have some features that warrant clinical approaches differing from those for female breast cancer.
[4] Features of male breast cancers that differ from those in females include variations in their presentations, associations with other diseases, associations with non-medical predisposing conditions, expressions of key breast cancer-related hormones, causes (including frequency and forms of genetic alterations), tumor types, and treatments.
Female breast cancer most often presents as a mass found on routine screening mammography or self-examination.
At this time or later, depending on further findings such as results of a biopsy, the women may be evaluated by medical imaging techniques such as ultrasonography, mammography, CT scans, magnetic resonance imaging, positron-emission tomography, scintimammography, and/or single-photon emission computed tomography to determine the extent of the primary tumor and presence of nearby lymph node and/or distant tissue lesions that may be metastases.
These differences appear to underlie findings that the diagnosis of breast cancer is made later in males than females (average age 67 vs. 63 years old, respectively).
[10] Studies have reported that males more often than females present with breast cancers that have spread to nearby axillary lymph nodes and appear more aggressive based on their microscopic histopathology.
[10] However, a large study by the Surveillance, Epidemiology, and End Results program of the National Institutes of Health ranked breast cancer severity based on their TNM stage.
Men with a history of high alcohol consumption and men with occupations entailing long-term exposure to high temperatures (e.g. such as to blast furnaces, steel works, and rolling mills, i.e. mills processing metals), petrol emissions, or exhaust emissions have had, in some studies, increased risks of developing breast cancer.
[20] Studies have reported 1) lower rates of breast cancer (i.e. by 20-25%) in men with an employment history involving high levels of physical activity and 2) higher rates of breast cancer in men with an employment history involving low levels of physical activity.
[22] However, most studies show that the protective effect in female breast cancer is a 13% decreased risk in high versus low physical activity groups and is limited to postmenopausal women.
[4][21] Other states in which males have excessive estrogen relative to androgen levels and increased rates of developing MBC include liver cirrhosis (females with liver cirrhosis do not have an increased incidence of breast cancer), testicular dysfunction (due to, e.g. undescended testes, congenital inguinal hernia, orchitis, i.e. inflammation of the testes caused by, e.g. mumps or testicular malignancies), and consumption of hormonal drugs for, e.g. gender reassignment therapy.
[4][27] (One study reported a 46-fold increased rate of MBC in trans women, i.e. gender reassignment from male to female.)
[10] Earlier studies regarded gynecomastia as a risk factor for MBC but more recent work suggests that this has not been established.
The National Comprehensive Cancer Network recommends self-breast examination starting at age 35 for men with mutations in either BRCA gene.
[5] Mutations in other genes such as CHEK2, PALB2, PTEN,[33] ATM[4] and RAD51L3 (also termed RAD51D)[21] have been reported to occur uncommonly in, and may confer an increased risk of developing, MBC.
These genes are uncommon causes of the hereditary breast-ovarian syndrome but for the most part are associated with breast but not the other cancers in men.
The most common surgical treatment for MBC tumors has been total mastectomy with breast-conserving surgery being performed in a much smaller proportion of males than females.
44.5%, respectively); b) Tamoxifen therapy improved overall survival rates compared to treatments not using tamoxifen at 5 years (81.7 vs. 71.4, respectively) and 10 years (57.9 vs. 50.4, respectively); c) Tamoxifen therapy improved 5 year overall survival rates compared to therapy with aromatase inhibitors (i.e. medicines that block the production of estrogens); and d) therapy with an aromatase inhibitor plus a GNRH agonist (i.e. medicines that indirectly inhibit production of estrogens, progesterone, and androgens[37]) improved the 5 year overall survival rate over an aromatase inhibitor without a GnRH agonist;[38] Tamoxifen is routinely and very commonly prescribed for treating all stages of MBC.