Older age, symptoms, or anemia: Which factors increase colorectal cancer risk with a positive fecal immunochemical test?

J Gastroenterol Hepatol. 2020 Jun;35(6):1002-1008. doi: 10.1111/jgh.14888. Epub 2019 Dec 11.

Abstract

Background and aim: Fecal immunochemical tests (FIT) are used to screen asymptomatic individuals aged 50-74 years for colorectal cancer (CRC) within the Australian screening program. Gastrointestinal symptoms or iron deficiency anemia (IDA) may also drive primary care physicians to request a FIT. This study aimed to examine factors that may increase neoplasia risk associated with a positive FIT, specifically age, gastrointestinal symptoms, or IDA.

Methods: A retrospective audit was performed on colonoscopies performed in a single hospital in South Australia for a positive FIT (from all referral sources) between 2014 and 2017. Patients aged < 50 years, or who had a colonoscopy in the preceding 5 years, were excluded. A subgroup (n = 198) was evaluated to assess whether age ≥ 75 years, symptoms, or IDA, as well as other demographics, comorbidities, and medications, were associated with risk of neoplasia. Features found to be associated with risk for CRC or high-risk adenoma were examined in the entire cohort using multivariate analysis.

Results: Colonoscopies (750/4221, 17.8%) were completed in patients ≥ 50 years for a positive FIT. Of these, 7.6% (n = 57) also had gastrointestinal symptoms, 5.5% (n = 41) IDA, and 13.1% (n = 98) were ≥ 75 years. At colonoscopy, 2.8% (n = 21) were diagnosed with CRC and 23.2% (n = 174) with high-risk adenoma. CRC was more prevalent in ≥ 75 years compared with 50-74 years (7.1% vs 2.1%, P = 0.005), and associated with symptoms (15.8% vs 1.7%, P < 0.001), and IDA (14.6% vs 2.1%, P < 0.001). Multivariate analysis showed that IDA (odds ratio 7.68, P < 0.001) and symptoms (odds ratio 10.37, P < 0.001), but not age, were independent risk factors for CRC.

Conclusion: The presence of gastrointestinal symptoms or IDA, independent of age, is associated with an increased risk for CRC following a positive FIT.

Keywords: colonoscopy; colorectal cancer (CRC); fecal immunochemical test (FIT); iron deficiency anemia (IDA); symptoms.

MeSH terms

  • Age Factors
  • Aged
  • Anemia, Iron-Deficiency*
  • Cohort Studies
  • Colonoscopy
  • Colorectal Neoplasms / diagnosis*
  • Colorectal Neoplasms / etiology*
  • Diagnostic Techniques, Digestive System*
  • Early Detection of Cancer / methods*
  • Feces / chemistry*
  • Female
  • Humans
  • Male
  • Mass Screening / methods*
  • Middle Aged
  • Retrospective Studies
  • Risk
  • Risk Factors