Oral cancer via the bargain bin : the role of smokeless tobacco in the etiology of oral cancer

Abstract

Background: Oral cancer combined with the other cancers of the head and neck region constitute the sixth most common cancer in the world. Oral cancer is a major public health challenge in South Asia. Pakistan, India, Bangladesh and Sri Lanka have some of the highest incidence and prevalence rates of oral cancer in the world. Approximately 16,000 new cases of oral cancer are diagnosed each year in Pakistan and around 6,000 Pakistanis lose their lives to this malignancy every year. There is a disconnect between the research findings from the developed countries and the developing countries, with regards to the risk of oral cancer associated with smokeless tobacco use. Given the differences in the composition of the smokeless tobacco products used in different parts of the world, it is imperative that the health risks related with each of these products are assessed on an individual basis. Methods: A case-control study was carried out in the Khyber Pakhtunkhwa province of Pakistan from September 2014 until May 2015, to quantify the risk of oral cancer associated with the use of Naswar (smokeless tobacco). Additionally, three systematic reviews (including meta-analyses) of observational studies and two narrative reviews were carried out to address the secondary objectives of this dissertation. Results: We found an increased risk of oral cancer associated with the use of smokeless tobacco products in South Asia. The use of smokeless tobacco was also associated with an elevated risk of oral potentially malignant disorders. In Khyber Pakhtunkhwa, Pakistan, Ever-users of Naswar had a 21-fold increase in the risk of oral cancer compared to Never-users Odds ratio (OR) =21.2 (95% Confidence Interval (CI), (8.4-53.8) . An elevated risk of oral cancer associated with Naswar use was found among both women and men. The risk of oral cancer increased with the increasing frequency, total duration, and the intensity of Naswar use. 70% of the oral cancer burden of Khyber Pakhtunkhwa was attributable to Naswar. Discussion: The findings of the systematic reviews and the case-control study on Naswar are comparable to the existing literature. The results clearly demonstrate a high risk of oral cancer and related disorders, associated with the use of smokeless tobacco products like Naswar, Betel quid, and Gutkha. There is a lack of oral cancer research in Pakistan and the tobacco control policies of the country largely focus on tobacco smoking while neglecting smokeless tobacco. In order to tackle the growing burden of oral cancer in South Asia in general and Pakistan in particular, policies need to be in place to curb the use of smokeless tobacco products. These products need to be regulated and brought under the tobacco tax-net. Changes to the composition of these products, to make them less harmful to health, should also be looked into as an intervention.