Patterns of diagnosis for colorectal cancer: screening detected vs. symptomatic presentation

Colorectal cancer is a leading cause of cancer death in North America; studies have shown that screening improves survival. Conducted in British Columbia, Canada, this study was performed to identify the proportion of screening-eligible patients with sporadic colorectal cancer who are detected by screening tests vs. symptomatic presentation and to compare baseline patient and tumor characteristics of these two groups.

This retrospective cohort study identified 571 consecutive patients referred to the British Columbia Cancer Agency at aged 50 years and older presenting with a first diagnosis of invasive colorectal cancer between November 2002 and April 2003. Questionnaires for self-completion were mailed to all patients to capture: previous screening history, screening vs. symptomatic presentation, and demographic information.

Of 212 eligible respondents (37 percent response), 14 patients (6.6 percent) with a new CRC were detected by screening vs. 198 patients (93.4 percent) presenting with symptoms. Respondents were 59 percent male, average age at diagnosis was 69 years, 91 percent white, 37 percent rectal, and 18 percent M1 at diagnosis. No significant differences in the age, gender, ethnicity, socioeconomic status, tumor stage, and site were detected between the screened vs. symptomatic cohorts. Only 33 of 212 patients (15.6 percent) reported ever having a screening test. Nineteen of 198 cancers (9.6 percent) were diagnosed by symptomatic presentation despite a compliant screening history.

Less than 7 percent of patients with a new diagnosis of CRC were detected via a screening test. Furthermore, only 15 percent of screening-eligible respondents had ever been screened. Significant effort is required to increase knowledge and compliance for CRC screening.