Biology and Clinical Implications of Fecal Occult Blood Test Screen-Detected Colorectal Cancer

Shehara Mendis, Wei Hong, Sumitra Ananda, Ian Faragher, Ian Jones, Matthew Croxford, Malcolm Steel, Azim Jalali, Grace Gard, Yat Hang To, Margaret Lee, Suzanne Kosmider, Rachel Wong, Jeanne Tie, Peter Gibbs

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Background: Fecal occult blood test (FOBT)-based screening for colorectal cancer (CRC) reduces mortality, with earlier stage at diagnosis a prominent feature. Other characteristics of FOBT screen-detected cancers and any implications for clinical management have not been well explored. Methods: We examined a multisite clinical registry to compare the characteristics and outcomes of FOBT screen-detected CRC via the Australian National Bowel Cancer Screening Program (NBCSP), which is offered biennially to individuals aged 50-74 years, and age-matched non-screen-detected CRC in the same registry. All statistical tests were 2-sided. Odds ratios (ORs) were calculated using the Baptista-Pike method, and hazard ratios via the log-rank method. Results: Of 7153 registry patients diagnosed June 1, 2006, to June 30, 2020, 4142 (57.9%) were aged between 50 and 74 years. Excluding 406 patients with non-NBCSP screen-detected cancers and 35 patients with unknown method of detection, 473 (12.8%) were screen detected via the NBCSP, and 3228 (87.2%) were non-screen detected. Screen-detected patients were younger (mean age = 62.4 vs 64.2 years; P <. 001) and more medically fit (OR for ASA score 1-2 = 1.91, 95% confidence interval [CI] = 1.51 to 2.41; P <. 001). Pathologic characteristics within each stage favored the screen-detected patients. Stage III screen-detected colon cancers were more likely to receive adjuvant therapy (OR = 3.58, 95% CI = 1.52 to 8.36; P =. 002). Screen-detected patients had superior relapse-free (hazard ratio = 0.41, 95% CI = 0.29 to 0.60; P <. 001) and overall survival (hazard ratio = 0.22, 95% CI = 0.15 to 0.35; P <. 001), which was maintained in matched stage comparisons and multivariable analysis. Conclusions: Beyond stage at diagnosis, multiple other factors associated with a favorable outcome are observed in FOBT screen-detected CRC. Given the substantial stage-by-stage differences in survival outcomes, if independently confirmed, individualized adjuvant therapy and surveillance strategies could be warranted for FOBT screen-detected cancers.

Original languageEnglish
Article numberpkab100
Number of pages10
JournalJNCI Cancer Spectrum
Issue number1
Publication statusPublished - 1 Feb 2022

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