Colorectal cancer pre-diagnostic symptoms are associated with anatomic cancer site.

Background: Signs and red flag symptoms in colorectal cancer (CRC) patients who are below the recommended screening age are often overlooked, leading to delayed diagnosis and worse prognosis. This study investigates how patient pre-diagnostic symptoms are associated with anatomic site of their cancer and whether the association varies by age at CRC diagnosis.

Methods: We ascertained CRC patients' experienced symptoms and screening through medical abstractions from an ongoing population-based study of CRC patients identified through a SEER cancer registry (N = 626). We used logistic regression to estimate odds ratios and 95% confidence intervals for the association between symptoms and CRC anatomic site. Additional analyses were stratified by age at diagnosis. Early-onset was defined as less than 50 years of age at CRC diagnosis.

Results: Participants who experienced blood in stool were more likely (odds ratio (95% confidence interval)) to have rectal (vs. colon) cancer (4.37 (3.02, 6.33)), as were patients who experienced changes to stool (1.78 (1.21, 2.60)). Patients diagnosed with colon cancer were more likely to present with abdominal pain (0.30 (0.19, 0.47)), anemia (0.40 (0.21, 0.75)), other symptoms (0.33 (0.19, 0.55)) and no symptoms (0.68 (0.44, 1.04)). When stratifying by age at diagnosis, we found that the association between blood in stool and rectal tumor location was particularly pronounced for patients with early-onset CRC (6.48 (2.73, 15.41)).

Conclusions: Common pre-diagnostic red flag symptoms are associated with CRC anatomic site. These findings can inform best practices for gastroenterologist triage of care and early evaluation of CRC and are of key importance given the rise of early-onset (pre-screening age) CRC.

Trial Registration: Not applicable to this study and analysis.