Purpose: The contribution of adjuvant chemotherapy after chemoradiation therapy (CRT) in nasopharyngeal cancer (NPC) remains controversial. Plasma Epstein-Barr virus (EBV) DNA is a potential biomarker of subclinical residual disease in NPC. In this prospective, multicenter, randomized controlled trial, we used plasma EBV DNA to identify patients with NPC at a higher risk of relapse for adjuvant chemotherapy. Patients and Methods: Eligible patients with histologically confirmed NPC of Union for International Cancer Control stage IIB to IVB, adequate organ function, and no locoregional disease or distant metastasis were screened by plasma EBV DNA at 6 to 8 weeks after radiotherapy (RT). Patients with undetectable plasma EBV DNA underwent standard surveillance. Patients with detectable plasma EBV DNA were randomly assigned to either adjuvant chemotherapy with cisplatin and gemcitabine for six cycles (arm 1) or observation (arm 2). Patients were stratified for primary treatment (RT v CRT) and stage (II/III v IV). The primary end point was relapse-free survival (RFS). Results: Seven hundred eighty-nine patients underwent EBV DNA screening. Plasma EBV DNA was undetectable in 573 (72.6%) and detectable in 216 (27.4%); 104 (13.2%) with detectable EBV DNA were randomly assigned to arms 1 (n = 52) and 2 (n = 52). After a median follow-up of 6.6 years, no significant difference was found in 5-year RFS rate between arms 1 and 2 (49.3% v 54.7%; P = .75; hazard ratio for relapse or death, 1.09; 95% CI, 0.63 to 1.89). The level of post-RT plasma EBV DNA correlated significantly with the hazards of locoregional failure, distant metastasis, and death. Conclusion: In patients with NPC with detectable post-RT plasma EBV DNA, adjuvant chemotherapy with cisplatin and gemcitabine did not improve RFS. Post-RT plasma EBV DNA level should be incorporated as the selection factor in future clinical trials of adjuvant therapy in NPC.

Studies of related individuals have consistently demonstrated notable familial aggregation of cancer. We aim to estimate the heritability and genetic correlation attributable to the additive effects of common single-nucleotide polymorphisms (SNPs) for cancer at 13 anatomical sites. Between 2007 and 2014, the US National Cancer Institute has generated data from genome-wide association studies (GWAS) for 49 492 cancer case patients and 34 131 control patients. We apply novel mixed model methodology (GCTA) to this GWAS data to estimate the heritability of individual cancers, as well as the proportion of heritability attributable to cigarette smoking in smoking-related cancers, and the genetic correlation between pairs of cancers. GWAS heritability was statistically significant at nearly all sites, with the estimates of array-based heritability, hl (2), on the liability threshold (LT) scale ranging from 0.05 to 0.38. Estimating the combined heritability of multiple smoking characteristics, we calculate that at least 24% (95% confidence interval [CI] = 14% to 37%) and 7% (95% CI = 4% to 11%) of the heritability for lung and bladder cancer, respectively, can be attributed to genetic determinants of smoking. Most pairs of cancers studied did not show evidence of strong genetic correlation. We found only four pairs of cancers with marginally statistically significant correlations, specifically kidney and testes (ρ = 0.73, SE = 0.28), diffuse large B-cell lymphoma (DLBCL) and pediatric osteosarcoma (ρ = 0.53, SE = 0.21), DLBCL and chronic lymphocytic leukemia (CLL) (ρ = 0.51, SE =0.18), and bladder and lung (ρ = 0.35, SE = 0.14). Correlation analysis also indicates that the genetic architecture of lung cancer differs between a smoking population of European ancestry and a nonsmoking Asian population, allowing for the possibility that the genetic etiology for the same disease can vary by population and environmental exposures. Our results provide important insights into the genetic architecture of cancers and suggest new avenues for investigation.