Subset testing and analysis of multiple phenotypes

Immune-related conditions and cancer-specific mortality among older adults with cancer in the United States

Immunity may play a role in preventing cancer progression. We studied associations of immune-related conditions with cancer-specific mortality among older adults in the United States. We evaluated 1 229 443 patients diagnosed with 20 common cancer types (age 67-99, years 1993-2013) using Surveillance Epidemiology and End Results-Medicare data. With Medicare claims, we ascertained immune-related medical conditions diagnosed before cancer diagnosis (4 immunosuppressive conditions [n = 3380 affected cases], 32 autoimmune conditions [n = 155 766], 3 allergic conditions [n = 101 366]). For each cancer site, we estimated adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for cancer-specific mortality associated with each condition, applying a Bonferroni cutoff for significance (P < 5.1 × 10-5 ). Bayesian metaanalysis methods were used to detect patterns across groups of conditions and cancers. We observed 21 associations with cancer-specific mortality at the Bonferroni threshold. Increased cancer-specific mortality was observed with rheumatoid arthritis for patients with melanoma (aHR 1.51, 95% CI 1.31-1.75) and breast cancer (1.24, 1.15-1.33)), and with hemolytic anemia for bladder cancer (2.54, 1.68-3.82). Significant inverse associations with cancer-specific mortality were observed for allergic rhinitis (range of aHRs: 0.84-0.94) and asthma (0.83-0.95) for cancers of the lung, breast, and prostate. Cancer-specific mortality was nominally elevated in patients with immunosuppressive conditions for eight cancer types (aHR range: 1.27-2.36; P-value range: 7.5 × 10-5 to 3.1 × 10-2 ) and was strongly associated with grouped immunosuppressive conditions using Bayesian metaanalyses methods. For older patients with several cancer types, certain immunosuppressive and autoimmune conditions were associated with increased cancer-specific mortality. In contrast, inverse associations with allergic conditions may reflect enhanced immune control of cancer.

Patterns of Human Leukocyte Antigen Class I and Class II Associations and Cancer

Human leukocyte antigen (HLA) gene variation is associated with risk of cancers, particularly those with infectious etiology or hematopoietic origin, given its role in immune presentation. Previous studies focused primarily on HLA allele/haplotype-specific associations. To answer whether associations are driven by HLA class I (essential for T-cell cytotoxicity) or class II (important for T-cell helper responses) genes, we analyzed GWAS from 24 case-control studies and consortia comprising 27 cancers (totaling >71,000 individuals). Associations for most cancers with infectious etiology or of hematopoietic origin were driven by multiple HLA regions, suggesting that both cytotoxic and helper T-cell responses are important. Notable exceptions were observed for nasopharyngeal carcinoma, an EBV-associated cancer, and CLL/SLL forms of non-Hodgkin lymphomas; these cancers were associated with HLA class I region only and HLA class II region only, implying the importance of cytotoxic T-cell responses for the former and CD4+ T-cell helper responses for the latter. Our findings suggest that increased understanding of the pattern of HLA associations for individual cancers could lead to better insights into specific mechanisms involved in cancer pathogenesis. SIGNIFICANCE: GWAS of >71,000 individuals across 27 cancer types suggest that patterns of HLA Class I and Class II associations may provide etiologic insights for cancer.