Positive Predictive Value of Symptoms for Early-Onset Colorectal Cancer

Diagnosing colorectal cancer in people below age 50 relies largely on the evaluation of symptoms despite recent recommendations to initiate screening at age 45. There is limited information on the positive predictive value (PPV) of symptoms as indicators of early-onset colorectal cancer.

We identified patients aged 42 to 49 years in three community-based health systems between 2012 and 2020 whose first recorded colonoscopy had a diagnostic indication, with symptoms present in the two years before the colonoscopy. We computed the PPV for colorectal cancer by each individual symptom, combinations of the three most common symptoms, and combinations of the three symptoms with the highest PPVs and computed 95% confidence intervals (CI). We also evaluated the PPV of recent symptoms stratified according to the timing of onset and estimated the PPV of symptoms when followed by positive or negative fecal testing.

The study included 28,198 patients. The PPV for specific symptoms, with or without other symptoms, was 2.4% (95% CI, 2.2%-2.7%) for blood loss and 4.5% (95% CI, 3.3%-5.9%) for positive fecal testing. Pairwise and three-way combinations of blood loss, diarrhea, and abdominal mass had PPV point estimates for colorectal cancer above 3%.

Our study suggests that specific symptoms and combinations may identify patients with a ≥3% prevalence of colorectal cancer in those aged 42 to 49 and that fecal testing results may further identify patients with a higher probability of colorectal cancer.

Future research is needed to develop high PPV strategies for identifying early-onset colorectal cancer without compromising sensitivity. See related In the Spotlight, p. 1233.