Screening Guideline Updates and New Treatments in Colon Cancer

The screening and treatment landscape for colon cancer is changing rapidly.^1,2 The recommended age for screening has been lowered to 45 from 50 years due to the increased incidence of colon cancer in younger people, especially among African American individuals.^1,3 New screening recommendations also incorporate fecal immunochemical tests (FIT) and multitarget stool DNA tests, where abnormal results on stool-based screening should lead to timely colonoscopy.^1,4 For veterans, colon cancer screening rates tend to vary based on VA health coverage, race, income, and mental health status but are higher than for the general public.^5,6

The field of colon cancer treatment, along with the rest of oncology, is moving toward molecularly targeted therapies and immunotherapy. In the VA, NPOP provides tumor NGS that predicts response to molecularly targeted therapies.⁷ In addition, NGS can identify microsatellite instability (MSI)-high colon cancer. In MSI-high colon cancer, immunotherapy alone provides better PFS than older traditional chemotherapeutic regimens.⁸ Gene alterations of interest in colon cancer include NRAS, KRAS, BRAF, and HER2, which, along with MSI status and PD-L1 expression levels, guide the choice of therapy offered.^2,8 The use of liquid biopsy panels that assess the quantity of circulating tumor DNA (ctDNA) is also being studied in veterans.^9,10 Liquid biopsies can be used to assess treatment response, if minimal residual disease is present after surgical resection or if new mutations develop during treatment.⁹ All in all, screening guidelines are adapting as new data and tests become available, while the field of colon cancer treatment is evolving based on increased access to NGS and appropriate use of molecularly targeted therapy and immunotherapy.

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