Association of Primary Care Physician Density With Metastatic Cancer at Initial Diagnosis: A Population-Based Study of 7 Cancers.

Abstract

Background: Patients with metastatic cancer at initial diagnosis have the worst prognosis. Despite their involvement in initial assessment, the relationship between Primary Care Physician availability and metastatic cancer at initial diagnosis remains unexplored. Our objective was to determine whether Primary Care Physician availability is associated with patients having metastatic cancer at initial diagnosis.

Methodology: This was a cross-sectional study of patients aged ≥ 18 and diagnosed with breast, colorectal, liver, lung, ovarian, pancreatic, or prostate cancer from 2015 to 2019. Population-based Texas and California cancer registries were used for patient data. The main exposure was county-level Primary Care Physician density per 3500 individuals. Additional exposures included demographic factors, insurance, rural-urban continuum codes, county poverty rates, and US State at Diagnosis. The primary outcome was adjusted odds of metastatic cancer at initial diagnosis. Subgroup analyses based on insurance type, age group, and metropolitan residence were performed. Models were stratified by cancer type.

Results: Overall, 708,451 patients were included. On combined multivariable analysis, with each additional Primary Care Physician per 3500 individuals, the odds for primary outcome decreased by 2% to 6%. In a stratified analysis using Primary Care Physician density per 3500 individuals as a categorical variable, compared with counties with < 1 Primary Care Physician, counties with 3 or more Primary Care Physicians had reduced odds of primary outcome for multiple cancer types with no statistically significant difference for counties with 1-1.9 Primary Care Physicians.

Conclusion: Increased Primary Care Physician availability was associated with a nonlinear decrease in odds for metastatic cancer at diagnosis. Thus, increasing physician density can possibly lower the likelihood of metastatic cancer at initial diagnosis.