Effect of screening on oral cancer mortality in Kerala , India : a cluster-randomised controlled trial

colleagues report the first solid evidence that periodic examination of the oral cavity can reduce mortality from oral cancer in high-risk individuals. These results come from the Kerala screening trial, a cluster randomised trial, designed to have 80% power to detect a 35% reduction in oral cancer mortality within 12 years of enrolment between the intervention and control group, through rounds of screening every 3 years. The investigators report that, 9 years after the start of screening, there was a significant 32% reduction in mortality in high-risk individuals in the intervention group (42% when only male tobacco/alcohol users are considered). Overall, these data suggest that oral visual screening in high-risk patients could prevent about 40 000 deaths from oral cancer worldwide. The reported data could be read in two ways. The first is the methodological evaluation of oral cancer screening itself. From this point of view, are the outcomes reported by Sankaranarayanan and colleagues adequately supported by the study design or do limitations exist? For example, the restricted-block randomisation can be potentially imbalanced when the number of clusters is small. Also, the recruitment of non-medical health workers raises concerns about the sensitivity and specificity to detect lesions and patients’ compliance with referral. A screening interval of 3 years is long and the percentage of patients who did not get biopsy was high. Finally, clinical and histopathological diagnostic criteria were not clearly reported and variations in definitions and management of oral lesions can influence screening outcomes. On the other hand, the data suggest perhaps the right perspective in the fight against oral cancer—supporting prevention through screening as a potential major target of every health organisation worldwide. Oral cancer is a significant public-health threat, accounting for 270 000 new cases annually and with one of the lowest survival rates (fewer than 50% of patients surviving more than 5 years). Furthermore, in the past few decades despite advances in the detection and treatment of many other malignancies, this rate has remained disappointingly low and relatively constant. Rather than prevalence, the most peculiar characteristic of oral cancer is the apparently unexplainable imbalance between its global burden and the potential theoretical ease in decreasing morbidity and mortality with early detection. Oral cancer is almost always preceded by visible changes in the oral mucosa (figure, A and B), which allows clinicians to detect and treat effectively early intraepithelial stages of oral carcinogenesis. Nevertheless, most oral cancers are currently detected at a late stage, when treatment is complex, costly, and has poor outcomes (figure, C and D). Paradoxically, the percentage of oral cancers diagnosed in the early stages is similar to that of colon cancers (36%). Lack of awareness in the public of the signs, symptoms, and risk factors for oral cancer, as well as a disappointing absence of prevention and early detection by health-care providers, are both believed to be responsible for the diagnostic delay. It is strange to think that, at present, pelvic examination and Pap smears appear more acceptable than looking in the mouth, for both patients and physicians. Current research mainly focuses on therapies for advanced oral cancers. As a result we have been spending hundreds of millions of dollars in treating patients, two-thirds of whom will die within 3–5 years, consuming educational Comment