Regional Colon and Rectal Surgeon Density Is Associated with Variation in Rectal Cancer Surgical Treatment: A Dartmouth Atlas Study.

: Recent reports reflect the increased enthusiasm for restorative reconstruction after a proctectomy (LAR) for rectal cancer in appropriate candidates. Despite this, abdominoperineal resection (APR) remains common. We aimed to examine the effect of the colorectal surgeon density in a hospital referral region (HRR) on the rates of LARs and APRs performed. : We conducted a retrospective cohort study of Medicare-participating hospitals in the United States for the fiscal year 2014. Our cohort was all Medicare beneficiaries (MBs) with rectal cancer (ICD-9: 154.1) who underwent an intervention of an LAR (CPT: 44145, 44146, 44207, 44298, 45112, 45397) or an APR (CPT: 45110 or 45395). We compared the APR and LAR rates per HRR with the density of board-certified colorectal surgeons per HRR (divided into low-, medium-, and high-density HRRs) using membership and zip code data from the American Board of Colon and Rectal Surgery. : A total of 3366 beneficiaries underwent LARs and 1821 beneficiaries underwent APRs for rectal cancer in 2014. The national rates of LARs and APRs were 12.12 and 6.66 per 100,000 MBs, respectively. The individual rates were available for 104 HRRs for the LARs and 46 HRRs for the APRs (those with >10 procedures/year). The median rates of LARs per 100,000 MBs in the low-, medium-, and high-density groups were 12.13, 13.05, and 14.25, respectively. The median rates of APRs per 100,000 MBs in the low-, medium-, and high-density groups were 7.69, 7.29, and 6.23, respectively. Both trends were significant by a test of trend. : A higher colorectal surgeon density was associated with increased rates of LARs and decreased rates of APRs for Medicare beneficiaries.