Incidence and risk factors for colorectal neoplasia in patients with oral squamous cell carcinoma.

AIM: Colorectal adenoma and cancer are not regarded as being associated with primary oral cancer. The aim of this study was to determine whether screening colonoscopy should be performed for patients with oral cancer in addition to the upper gastrointestinal endoscopic screening that is now routinely performed. METHOD: Between 2007 and 2013, 162 patients with oral squamous cell carcinoma were enrolled at Tokyo Dental College, Ichikawa General Hospital, and 136 individuals were assigned to colonoscopic surveillance. Advanced neoplasia was defined as an adenoma >/= 10 mm, adenoma with villous histology or high-grade dysplasia regardless of size and invasive cancer. Associations between advanced neoplasia and clinical factors, including age, sex, body mass index, physical activity, smoking, alcohol consumption and oral cancer site and staging were determined. RESULTS: Advanced neoplasia, including five invasive cancers, was identified in 32 (23.5%) patients. An age- and sex-adjusted multivariate analysis revealed that smoking (Brinkmann index > 400; OR = 3.24, 95% CI = 1.28-8.18), alcohol consumption (lifetime pure ethanol consumption > 600 l; OR = 2.84, 95% CI = 1.18-6.79) and a diagnosis of cancer of the floor of the mouth (OR = 7.97, 95% CI = 2.49-25.46) were independent risk factors for advanced colorectal neoplasia. CONCLUSION: The prevalence of advanced colorectal neoplasia is unexpectedly high in patients with oral cancer. It should be recognized as a second primary tumour of oral cancer. Screening of oral cancer patients by colonoscopy should be routine practice, particularly among smokers and patients with a high intake of alcohol and cancer of the floor of the mouth.