Patient and tumour characteristics of screening‐age adults diagnosed with screen‐detected versus symptomatic colon cancer

AIM: International studies have shown that most colon cancers are diagnosed among people with symptoms, but research is limited in the United States. We conducted a retrospective study with adults aged 50–85 years diagnosed with stage I-IIIA colon cancer in 1995–2014 in two US healthcare systems. METHOD: Mode of detection (screening or symptomatic) was ascertained from medical records. We estimated unadjusted odds ratios (OR) and 95% confidence intervals (CI) comparing detection mode by patient factors at diagnosis (year, age, sex, race, smoking status, body mass index [BMI], Charlson score), pre-diagnostic primary care utilization, and tumor characteristics (stage, location). RESULTS: Of 1,675 people with colon cancer, 38.4% were screen-detected, while 61.6% were diagnosed following symptomatic presentation. Screen-detected cancer was more common among those diagnosed in 2010–2014 vs. 1995–1999 (OR=1.65, 95%CI=1.19–2.28), and those with a BMI of 25-0 (OR=0.71, 95%CI=0.56–0.91 for score=1, OR=0.34, 95%CI=0.26–0.45 for score=2+), and those with 2+ pre-diagnostic primary care visits (OR=0.53, 95%CI=0.37–0.76) vs. 0 visits. The odds of screen detection were lower among patients diagnosed with stage IIA (OR=0.33, 95%CI=0.27–0.41) or IIB (OR=0.12, 95%CI=0.06–0.24) cancers vs. stage I. CONCLUSION: Most colon cancers among screen-eligible adults were diagnosed following symptomatic presentation. Even with increasing screening rates over time, research is needed to better understand why specific groups are more likely to be diagnosed when symptomatic and identify opportunities for interventions.