Abstract
Identifying risk protein targets and their therapeutic drugs is crucial for effective cancer prevention. Here, we conduct integrative and fine-mapping analyses of large genome-wide association studies data for breast, colorectal, lung, ovarian, pancreatic, and prostate cancers and characterize 710 lead variants independently associated with cancer risk. Through mapping protein quantitative trait loci (pQTLs) for these variants using plasma proteomics data from over 75,000 participants, we identify 365 proteins associated with cancer risk. Subsequent colocalization analysis identifies 101 proteins, including 74 not reported in previous studies. We further characterize 36 potential druggable proteins for cancers or other disease indications. Analyzing >3.5 million electronic health records, we conducted analyses of emulated trials for 11 drugs across 290 comparisons and identified three drugs significantly associated with reduced colorectal cancer risk: caffeine vs. paroxetine (hazard ratio [HR], 0.51; 95% confidence interval [CI], 0.41-0.64), haloperidol vs. prochlorperazine (HR, 0.47; 95% CI, 0.33-0.68), and trazodone hydrochloride vs. paroxetine (HR, 0.49; 95% CI, 0.38-0.63). Conversely, caffeine was associated with increased cancer risk in comparison with finasteride (colorectal cancer) and fluoxetine (breast cancer). Meta-analysis identified six drugs significantly associated with cancer risk, including acetazolamide, which was associated with reduced colorectal cancer risk (HR, 0.79; 95% CI, 0.72-0.87). This study identifies previously unreported protein biomarkers and candidate drug targets across six major cancer types and highlights several approved drugs with potential chemopreventive effects.