Novel risk factors for primary prevention of oesophageal carcinoma: a case-control study from Sri Lanka.

BACKGROUND: Oesophageal carcinoma (OC) is one of the leading cancers in Sri Lanka. Its increasing incidence despite the implementation of various preventive activities addressing the conventional risk factors indicates the possibility of the existence of novel, country-specific risk factors. Thus, the identification of novel risk factors of OC specific to Sri Lanka is crucial for implementation of primary prevention activities. METHODS: A case-control study was conducted among 49 incident cases of OC recruited from the National Cancer Institute, Maharagama using a non-probability sampling method, and unmatched hospital controls (n = 196) excluded of having OC recruited from the endoscopy unit of the National Hospital of Sri Lanka. Data were collected using an interviewer administered questionnaire. Risk factors for OC were assessed by odds ratio (OR) with 95% confidence interval (CI). The risk factors were adjusted for possible confounding by logistic regression analysis. RESULTS: Of the study population, OC was common among males (69%) and the majority presented with squamous cell carcinoma (65%) at late stages (Stage IV: 45%; Stage III: 37%). Following adjusting for confounders, the risk factor profile for OC included; age > 65 years (OR = 4.0; 95% CI: 1.2-14.2); family history of cancer (OR = 5.04; 95% CI: 1.3-19.0); sub-optimal consumption of dietary fibre (OR = 3.58; 95% CI: 1.1-12.3); sub-optimal consumption of anti-oxidants (OR = 7.0; 95% CI: 2.2-22.5); over-consumption of deep fried food (OR = 6.68; 95% CI:2.0-22.6); 'high risk' alcohol drinking (OR = 11.7; 95% CI: 2.8-49.4); betel quid chewing (OR = 6.1; 95% CI: 2.0, 20.0); 'low' lifetime total sports and exercise activities (MET hours/week/year) (OR = 5.83; 95% CI: 1.5-23.0); agrochemicals exposure (OR = 6.57; 95% CI: 1.4-30.3); pipe-borne drinking water (OR = 5.62; 95% CI:1.7-18.9) and radiation exposure (OR = 4.64; 95% CI: 1.4-15.5). Significant effect modifications were seen between betel quid chewing and male sex (p = 0.01) and between ever exposure to radiation and age over 65 years (p = 0.04). CONCLUSIONS: Risk profile for OC includes novel yet modifiable risk factors in relation to diet, occupation, environment and health. Primary prevention should target these to combat OC in Sri Lanka.