Association Between Primary Care Use Prior to Cancer Diagnosis and Subsequent Cancer Mortality in the Veterans Affairs Health System.

Primary care physicians (PCPs) are significant contributors of early cancer detection, yet few studies have investigated whether consistent primary care translates to improved downstream outcomes. To evaluate the association of prediagnostic primary care use with metastatic disease at diagnosis and cancer-specific mortality (CSM). This cohort study used databases with primary care and referral linkage from multiple Veterans' Affairs centers from 2004 to 2017 and had a 68-month median follow-up. Analysis was completed between July 2021 and September 2022. Participants included veterans older than 39 years who had been diagnosed with 1 of 12 cancers. Inclusion criteria included known clinical staging, survival follow-up, cause of death, and receiving care at the Veterans Affairs health system (VA). Prediagnostic PCP use, measured in the 5 years prior to diagnosis. PCP visits were binned into none (0 visits), some (1-4 visits), and annual (5 visits). Metastatic disease at diagnosis, cancer-specific mortality (CSM) for entire cohort and stratified by tumor subtype. Among 245 425 patients representing 12 tumor subtypes, mean age was 65.8 (9.3) years, and the cohort skewed male (97.6%), and White (76.1%), with higher levels of comorbidity (58.6% with Charlson Comorbidity Index scores ≥2). Compared with no prior visit, some PCP use was associated with 26% decreased odds of metastatic disease at diagnosis (odds ratio [OR], 0.74; 95% CI, 0.71-0.76; P < .001) and 12% reduced risk of CSM (subdistribution hazard ratio [SHR], 0.88; 95% CI, 0.86-0.89; P < .001). Annual PCP use was associated with 39% decreased odds of metastatic disease (OR, 0.61; 95% CI, 0.59-0.63; P < .001) and 21% reduced risk of CSM (SHR, 0.79; 95% CI, 0.77-0.81; P < .001). Among tumor subtypes, prostate cancer had the largest effect size for prior PCP use on metastatic disease at diagnosis (OR for annual use, 0.32; 95% CI, 0.30-0.35; P < .001) and CSM (SHRfor annual use, 0.51; 95% CI, 0.48-0.55; P < .001). In this cohort study, increased primary care use before cancer diagnosis was associated with significant decreases in metastatic disease at diagnosis and cancer-related death, with potentially the greatest difference from annual use. PCPs play a vital role in cancer prevention, and additional resources should be allocated to assist these physicians.