Arvo building, Lecture room F025, address: Lääkärinkatu 1
Doctoral defence of M.Sc. Jayaram Dodda Junjannagari
The field of science of the dissertation is Epidemiology.
The opponent is Dr. Cherian Varghese (WHO, Switzerland). Professor Emeritus Matti Hakama acts as the custos.
The language of the dissertation defence is English.
Microscopically Confirmed Pharyngeal Cancer in South India : An epidemiological case-control study
Pharyngeal cancer is one of the 5 most common cancer sites in Indian men. A hospital based case control study was conducted at Kidwai memorial institute of oncology, Bangalore, Karnataka, South India with the objectives to assess the effect of socio economic factors, different patterns of tobacco smoking, chewing, alcohol drinking, dietary practices and exposure to the fire wood may affect risk of development of pharyngeal cancer in South India.
The study included 439 (374 males, 65 females) microscopically confirmed as pharyngeal cancer cases were included as case series. Each case was matched for age and sex with an equal number of healthy persons (attendants of patients) was included in the study as controls. In males, tobacco smoking (OR=4.4, 95% CI 2.6, 7.5), tobacco chewing (OR=2.2, 95% CI 1.3, 3.9) and alcohol drinking (OR=4.3, 95% CI 2.8, 6.4) were found to be significantly associated with pharyngeal cancer on conditional multiple logistic regression analysis. Overall Bidi smoking was stronger risk factor compared to overall cigarette smoking (ORbidi 5.0 vs. ORcig 1.1) and the strongest risk factor for pharyngeal cancer was found for current tobacco smokers with OR 7.0 (95% CI 3.8, 12.6) than the current alcohol drinkers with OR 5.2 (95% CI 3.3, 8.3). Consumption of only domestic beverages was a stronger risk factor compared to consumption of only foreign beverages for cancer of the pharynx (ORdomestic beverage 6.4 vs. ORforeign beverage 2.6).
Further analysis revealed a dose-response relationship between early age at start, increasing frequency, duration of habits are risk of pharyngeal cancer. High values of estimates of attributable risk percent (ARP) and population attributable risk percent (PARP) confirmed the positive impact of reduction or elimination of the tobacco and alcohol consumption practices on reducing the risk of pharyngeal cancer in the population of South India.
Increased duration of exposure to firewood smoke (cooking time in hours) in a day increased substantially the risk in females, for more than two hours in a day had the significant OR=6.2 (95% CI 2.3, 16.5), compared with less than 3 hours in a day and in males, a moderate duration of daily cooking time of less than or equal to an hour had no effect (OR 1.0; 95% CI 0.3, 3.0), and for those exposed for more than an hour an increased risk of odds ratio (OR 3.6; 95% CI 1.5, 8.4) was observed. Income, education and occupation that describe the socioeconomic status were the strongest correlates with pharyngeal cancer among the demographic factors. Other factors like consumption of fruit and vegetables were found to be inversely significantly associated in the outcome of pharyngeal cancer in the study population.
In summary, this study shows that smoking/chewing tobacco products, drinking domestic beverages commercially available in India are risk factors for pharyngeal cancer and that these data provide strong evidence that smoking bidi is even more hazardous than cigarette smoking in the development of pharyngeal cancer. Further, the risk increased with an increase of the number of bidis smoked, indicating a dose-response relationship (p<0.001). Consumption of fruit and vegetables were found to be inversely significantly associated in the outcome of pharyngeal cancer in the study population. The results also suggest that reducing indoor air pollution from fire wood fuel may contribute to prevention of pharyngeal cancer in India, in addition to tobacco and alcohol control programs.
The dissertation is published in the publication series of Acta Universitatis Tamperensis; 2271, Tampere University Press, Tampere 2017. The dissertation is also published in the e-series Acta Electronica Universitatis Tamperensis; 1772, Tampere University Press 2017.