Oncologists' Selection of Genetic and Molecular Testing in the Evolving Landscape of Stage II Colorectal Cancer.

Purpose: Little is known about the roles of genetic and molecular testing and Lynch syndrome screening in the formulation of predictive and prognostic assessments for patients with stage II colorectal cancer (CRC).

Methods: From 2012 to 2013, we surveyed medical oncologists in the Cancer Care Outcomes Research and Surveillance Consortium and evaluated oncologists' selection of microsatellite instability (MSI) and/or immunohistochemistry (IHC) for mismatch repair (MMR) proteins, germline testing for MMR genes, BRAF and KRAS mutation analysis, and Oncotype DX in stage II CRC. Physicians were randomly assigned to receive one of three vignettes that varied by strength of CRC family history. We used multivariable logistic regression to identify physician and practice characteristics associated with test selection.

Results: Among 327 oncologists, MSI and/or IHC for MMR proteins were most frequently selected (n = 205; 64%), with 82% versus 53% choosing MSI/IHC testing in patients with strong versus no CRC family history, respectively (adjusted odds ratio [OR], 3.87; 95% CI, 2.07 to 7.22). KRAS and Oncotype DX testing were chosen by 24% and 38% of oncologists, respectively. Graduates of non-US and Canadian medical schools and physicians compensated by fee-for-service or on the basis of productivity were more likely to choose KRAS testing versus those receiving salaries not on the basis of productivity (OR, 2.16; 95% CI, 1.17 to 3.99; and OR, 1.94; 95% CI, 1.02 to 3.66, respectively). Fee-for-service or productivity-based salaries were also associated with increased odds of Oncotype DX testing (OR, 2.04; 95% CI, 1.17 to 3.55).

Conclusion: Among surveyed oncologists, we found undertesting and overtesting related to genetic and molecular testing and Lynch syndrome screening for patients with stage II CRC,highlighting the need for improved implementation, targeted education, and evaluation of organizational and financial arrangements to promote the appropriate use of such tests.