<qa>  What is the leading cause of cancer deaths in India?Oral precancerous lesions OPL represent a valuable model for clinical trials for tobacco related cancers. However, due to the relatively low prevalence of this condition in the United States, subject accrual to such trials is slow. Conversely, in India, the prevalence of oral leukoplakia is among the highest in the world. Indeed oral cancer, caused by exposure to tobacco smoke, alcohol and betel nut quid, is the leading cause of cancer deaths in India. 