Breast cancer in men is a rare disease, accounting for ∼1% of all breast cancer cases. Although the epidemiologic literature regarding female breast cancer is extensive, relatively little is known about the etiology of male breast cancer (MBC). This review is intended to summarize the existing body of evidence on genetic and epidemiologic risk factors for breast cancer in men. Overall, the epidemiology of MBC presents similarities with the epidemiology of female breast cancer. Major genetic factors associated with an increased risk of breast cancer for men include BRCA2 mutations, which are believed to account for the majority of inherited breast cancer in men, Klinefelter syndrome, and a positive family history. Suspected genetic factors include AR gene mutations, CYP17 polymorphism, Cowden syndrome, and CHEK2. Epidemiologic risk factors for MBC include disorders relating to hormonal imbalances, such as obesity, testicular disorders (e.g., cryptorchidism, mumps orchitis, and orchiectomy), and radiation exposure. Suspected epidemiologic risk factors include prostate cancer,prostate cancer treatment, gynecomastia, occupational exposures (e.g., electromagnetic fields, polycyclic aromatic hydrocarbons, and high temperatures), dietary factors (e.g., meat intake and fruit and vegetable consumption), and alcohol intake.

Epithelial ovarian cancer (EOC) often presents with metastases and ascites. Granulocytic myeloid–derived suppressor cells are an immature population that impairs antitumor immunity. Since suppressive granulocytes in the ascites of patients with newly diagnosed EOC were morphologically mature, we hypothesized that PMN were rendered suppressive in the tumor microenvironment (TME). Circulating PMN from patients were not suppressive but acquired a suppressor phenotype (defined as ≥1 log ₁₀ reduction of anti-CD3/CD28–stimulated T cell proliferation) after ascites supernatant exposure. Ascites supernatants (20 of 31 supernatants) recapitulated the suppressor phenotype in PMN from healthy donors. T cell proliferation was restored with ascites removal and restimulation. PMN suppressors also inhibited T cell activation and cytokine production. PMN suppressors completely suppressed proliferation in naive, central memory, and effector memory T cells and in engineered tumor antigen–specific cytotoxic T lymphocytes, while antigen-specific cell lysis was unaffected. Inhibition of complement C3 activation and PMN effector functions, including CR3 signaling, protein synthesis, and vesicular trafficking, abrogated the PMN suppressor phenotype. Moreover, malignant effusions from patients with various metastatic cancers also induced the C3-dependent PMN suppressor phenotype. These results point to PMN impairing T cell expansion and activation in the TME and the potential for complement inhibition to abrogate this barrier to antitumor immunity.

Uncontrolled proliferation and increased motility are hallmarks of neoplastic cells, therefore markers of proliferation and motility may be valuable in assessing tumor progression and prognosis. MCM2 is a member of the minichromosome maintenance (MCM) protein family. It plays critical roles in the initiation of DNA replication and in replication fork movement, and is intimately related to cell proliferation. Ki-67 is a proliferation antigen that is expressed during all but G0 phases of the cell cycle. Gelsolin is an actin-binding protein that regulates the integrity of the actin cytoskeletal structure and facilitates cell motility. In this study, we assessed the prognostic significance of MCM2 and Ki-67, two markers of proliferation, and gelsolin, a marker of motility, in non-small cell lung cancer (NSCLC). 128 patients with pathologically confirmed, resectable NSCLC (stage I-IIIA) were included. Immunohistochemistry was utilized to measure the expressions of these markers in formalin-fixed, paraffin-embedded tumor tissues. Staining and scoring of MCM2, Ki-67 and gelsolin was independently performed. Analyses were performed to evaluate the prognostic significance of single expression of each marker, as well as the prognostic significance of composite expressions of MCM2 and gelsolin. Cox regression and Kaplan-Meier survival analysis were used for statistical analysis. Of the three markers, higher levels of gelsolin were significantly associated with an increased risk of death (adjusted RR = 1.89, 95% CI = 1.17-3.05, p = 0.01), and higher levels of MCM2 were associated with a non-significant increased risk of death (adjusted RR = 1.36, 95% CI = 0.84-2.20, p = 0.22). Combined, adjusted analyses revealed a significantly poor prognostic effect for higher expression of MCM2 and gelsolin compared to low expression of both biomarkers (RR = 2.32, 95% CI = 1.21-4.45, p = 0.01). Ki-67 did not display apparent prognostic effect in this study sample. The results suggest that higher tumor proliferation and motility may be important in the prognosis of NSCLC, and composite application of biomarkers might be of greater value than single marker application in assessing tumor prognosis.

Although a large number of epidemiological studies have examined the role of aspirin in the chemoprevention of colon cancer and other solid tumors, there is a limited body of research focusing on the association between aspirin and lung cancer risk. We conducted a hospital-based case-control study to evaluate the role of regular aspirin use in lung cancer etiology. Study participants included 868 cases with primary, incident lung cancer and 935 hospital controls with non-neoplastic conditions who completed a comprehensive epidemiological questionnaire. Participants were classified as regular aspirin users if they had taken the drug at least once a week for at least one year. Results indicated that lung cancer risk was significantly lower for aspirin users compared to non-users (adjusted OR = 0.57; 95% CI 0.41–0.78). Although there was no clear evidence of a dose-response relationship, we observed risk reductions associated with greater frequency of use. Similarly, prolonged duration of use and increasing tablet years (tablets per day × years of use) was associated with reduced lung cancer risk. Risk reductions were observed in both sexes, but significant dose response relationships were only seen among male participants. When the analyses were restricted to former and current smokers, participants with the lowest cigarette exposure tended to benefit most from the potential chemopreventive effect of aspirin. After stratification by histology, regular aspirin use was significantly associated with reduced risk of small cell lung cancer and non-small cell lung cancer. Overall, results from this hospital-based case-control study suggest that regular aspirin use may be associated with reduced risk of lung cancer.

Caffeine has been suggested as a possible risk factor for breast cancer, potentially through its effect of facilitating the development of benign breast disease. However, coffee and tea also contain polyphenols, which exhibit anticarcinogenic properties. A hospital-based, case-control study was conducted to evaluate the role of coffee, decaffeinated coffee, and black tea in breast cancer etiology. Study participants included 1932 cases with primary, incident breast cancer and 1895 hospital controls with nonneoplastic conditions. All participants completed a comprehensive epidemiological questionnaire. Among premenopausal women, consumption of regular coffee was associated with linear declines in breast cancer risk (P for trend = 0.03); consumers of ≥4 cups/d experienced a 40% risk reduction (odds ratio = 0.62, 95% CI 0.39–0.98). No clear associations between intake of black tea or decaffeinated coffee and breast cancer risk were noted among premenopausal women, although black tea was associated with a protective effect unique to a subsample of cases with lobular histology. Among postmenopausal women, breast cancer risk was not associated with consumption of coffee, tea, or decaffeinated coffee. Results among postmenopausal women did not differ by histologic subtype. Our findings support a protective effect of coffee intake on premenopausal, but not postmenopausal breast cancer risk. Further studies are warranted to confirm these findings.