Prakash C. Gupta*, Cecily S. Ray**

Transcription

1 Health Administrator Vol: XVII, Number 1: 85-92,pg. TOBACCO RELATED CANCER - ITS IMPACT ON THE HEALTH ECONOMY Prakash C. Gupta*, Cecily S. Ray** I. MAGNITUDE OF THE PROBLEM Each year in India an estimated total of 700, ,000 new cancers are diagnosed (National Cancer Registry Programme (NCRP), 2001; Murthy et al., 1990; Yeole and Jussawalla, 1992). Nearly half of all cancers in men occur at sites associated with tobacco use (35.6% to 50.0% in the six population based registries). These sites include: mouth (oral cavity), lip and tongue, oropharynx, hypopharynx, pharynx, oesophagus, larynx, lung and urinary bladder. In women, less than one fifth of cancers occur at these sites, (10.1% to 17.3% in the six Registries), predominantly in oesophagus and oral cavity, but cancers of the cervix and breast constitutes over 40% of all cancers. The lower proportion of tobacco related cancers (TRCs) among women is mostly explained by the fact that, tobacco use, especially smoking, is more common among men than among women. The number of newly diagnosed TRCs each year in India has been estimated at approximately 250,000 (NCRP, 2001). In men, lung cancer is numerically the highest among all registered cancers in the six population-based registries (Bangalore, Barshi, Bhopal, Chennai, Delhi and Mumbai), but when cancers at all oral sites are combined - oral cavity, tongue and lip - oral cancer vies for first place with lung cancer. Registry-wise, lung cancer and oral cancer jockey for first place in four registries, with the exceptions of Bangalore, where oesophageal cancer is highest, and the rural registry at Barshi, where oropharyngeal cancer is highest. In the other registries, oropharyngeal cancer vies for third place along with oesophageal cancers, followed by laryngeal cancer, except in Delhi, where laryngeal cancer takes third place and cancers of the pharynx and of the oesophagus follow in nearly equal proportions. In women, oral cancer takes first place among TRCs in all the Registries; it is closely followed by oesophageal cancer and then the other TRCs follow in much smaller proportions. Cancers of the urinary bladder are also considered among the tobacco related cancers by the NCRP (IARC, 1986) and they form a small fraction of them in both men and women (NCRP, 2001). II. EVIDENCE FOR CAUSATION BY TOBACCO Epidemiological studies from around the world have provided sufficient evidence that the smoking of tobacco as cigarettes and bidis causes cancer of the respiratory tract and the upper digestive tract (International Agency for Research on Cancer (IARC), 1986). Similarly, smokeless tobacco including the forms most commonly used in South Asia, has been demonstrated to cause oral cancer and other head and neck cancers (IARC, 1985). The risks of these cancers are substantially increased in tobacco users who have a high-level consumption of alcohol (IARC 1986). Since evidence up to 1985 has been extensively reviewed by the IARC, in this paper largely post-1985 studies are included. III. ORAL CANCER Since 1985, eight case-control studies on oral cancers conducted in India from places as diverse as Bangalore, Bhopal, Chennai, Mumbai and Trivandrum, have given fresh evidence of the role of tobacco smoking and chewing in cancer causation. Five of these studies reported significant estimated relative risks (as odds ratios) to current chewers of pan with tobacco compared to non-chewers: in men, the relative risks varied from 1.8 (95% CI: ) to 5.8 (95% CI: ) (Rao and Desai, 1998; Rao et al, 1994; Nandakumar et al., 1990; Balaram et al., 2002; Dikshit and Kanhere, 2000) and, the values for women ranged from 30.4 (95% CI: ) for current chewers to 42.4 (95% CI: ) ever chewers in the two studies that included women (Nandakumar et al., 1990; Balaram et al., 2002). In three studies conducted in Trivandrum, male cases and controls were stratified by habit for having ever been a regular pan-tobacco chewer compared to those who never had chewed or smoked, relative risks for oral cancer at different sub-sites were reported at 8.75 (among non-drinkers only; 95% CI: ), 6.1 (95% CI: ) and 14.3 (95% CI: ) (Sankaranarayanan et al., 1989a, Sankaranarayanan et al., 1989b, Sankaranarayanan et al., 1990b). * Tata Institute of Fundamental Research, Mumbai, India , ** Tata Memorial Centre, Mumbai, India

2 All eight studies reported significant dose response trends for frequency of pan-tobacco chewing per day, and six out of the eight studies reported significant trends for duration as well. Retention of the quid overnight, analysed in one study, showed a 36-fold risk (Ghosh et al., 1996). Use of tobacco with lime was identified as a risk factor for oral and oropharyngeal cancers in a large hospital-based case-control study in Pakistan, yielding relative risks of 10.4 for women and 13.7 for men, compared to those who neither chewed nor smoked (Jafarey et al., 1977). Current users of nasal snuff-now a rarely used product - experienced a relative risk of 3.9 (P<0.05) for cancer of the gingiva (gums) in one study (Sankaranarayanan et al., 1989a) and elevated but not significant in another study on buccal mucosa (inner cheek) and lip (Sankaranarayanan et al., 1990b). The same eight studies on oral cancer mentioned earlier estimated relative risks for bidi smoking, the most common smoking habit in the country. In four of the studies, men who currently smoked bidis experienced relative risks varying from slightly elevated, but non-significant, to 1.6 (95% CI: ) (Dikshit and Kanhere, 2000; Nandakumar et al., 1990; Rao and Desai, 1998; Rao et al., 1994) In the three studies mentioned above from Trivandrum, relative risks for oral cancer at different oral sub-sites for men who had ever been regular bidi smokers, but who had never chewed tobacco, compared to those who had never smoked or chewed, were 3.8 (among non-drinkers only; 95% CI: ), 5.0 (95% CI: ) and 4.2 (95% CI: ) (Sankaranarayanan et al., 1989a, Sankaranarayanan et al., 1989b, Sankaranarayanan et al., 1990b). In general, except in one study, the risks for bidi smokers were higher than for cigarette smokers (Nandakumar et al., 1990). Alcohol appeared to be an independent risk factor for oral cancer (Sankaranarayanan et al., 1989a). In the Trivandrum studies, the relative risks for oral cancer for men who had ever been both bidi smokers and pan-tobacco chewers were 16.3 (among non drinkers only; 95% CI: ), 7.02 (95% CI: ) and 21.5 (95% CI: ) (Sankaranarayanan et al., 1989a, Sankaranarayanan et al., 1989b, Sankaranarayanan et al., 1990b). IV. OROPHARYNGEAL CANCER Three case-control studies of oropharyngeal cancers reported significant relative risks for current smokers (mainly of bidis) between 5.6 (95% CI: ) and 7.7 (95% CI: ). For current tobacco chewers (mainly betel quid) they reported non-elevated or mildly elevated, non-significant relative risks for oropharyngeal cancers (Rao et al, 1999, Rao and Desai, 1998; Dikshit and Kanhere, 2000). One of these studies reported a significant dose-response for frequency and duration of chewing but not for smoking (Dikshit and Kanhere, 2000). V. LARYNGEAL CANCER Results of two case-control studies on cancer of the larynx since 1985 are summarized here. One reported a relative risk for current bidi smoking at 2.3 (95% CI: ), adjusted for alcohol and chewing, and an elevated but non-significant one for tobacco chewing (mainly as pan) (Rao et al. 1999). The other study did not report the value for current smokers or chewers but showed a highly significant relative risk for occasional pan-tobacco chewing at (95% CI: ) (Sankaranarayanan et al., 1990a). It also showed a relative risk of 7.1 (95% CI: ) for bidi smoking for over 21 years and a highly significant trend for duration of bidi smoking (p<0.001) after adjustment for cigarette smoking and alcohol use (Sankaranarayanan et al., 1990a). VI. OESOPHAGEAL CANCER Odds ratios (relative risks) for tobacco chewers (generally with betel quid) were 2.9 (p<0.001) in two studies, after adjusting for smoking and alcohol (Nandakumar et al. 1996; Nayar et al., 2000), but were only mildly elevated and not significant in two other studies. Alcohol emerged as an independent risk factor for oesophageal cancer (Rao et al, 1989; Sankaranarayanan et al., 1991). Risks went up sharply for chewers as well as smokers for duration of habits for concomitant alcohol users (Rao et al., 1989). In the first two studies mentioned, the adjusted odds ratios for bidi smoking were 2.4 and 3.5, both highly significant (p<. 001), while for cigarette smoking they were above one, but not significant (Nayar et al., 2000 and Nandakumar et al., 1996). Analysis of the risk of cancer in the upper, middle and lower thirds of the oesophagus, bidi smoking seemed to affect the upper third more (OR = 7.1; 95% CI: ), whereas chewing, lower third (OR=6.6; 95% CI: ). The risk for bidi smoking was higher when combined with the habit of tobacco chewing (mainly as pan) (Nandakumar et al., 1996). A case-control study on cancer of the oesophagus from Assam found a dose response relationship with chewing of areca nut with or without tobacco. The adjusted odds ratios were highest for those who had been using fermented areca 86

3 nut (tamol) with any form of tobacco (7.1 for men and 3.6 for women) (Phukan et al., 2001). VII. LUNG CANCER Studies on lung cancer from around the world have led to the conclusion that the proportion of lung cancer attributable to smoking is of the order of 90% (IARC, 1986). In two case-control studies of lung cancer in India, bidi smokers had a relative risk of 5.8 (95% CI: ) and 11.6 (95% CI: ), while cigarette smokers had values of 5.6 (95% CI: ) and 7.7 (95% CI: ). Smokers of more than 20 bidis per day had relative risks of (95% CI: ) and 33.2 (95% CI: ) and smokers of more than 20 cigarettes daily, 5.8 (95% CI: ) and 26.8 (95% CI: ) (Gupta et al., 2001; Dikshit and Kanhere, 2000). It has been conclusively established that prolonged exposure to environmental tobacco smoke (ETS) causes lung cancer (Boffetta, 2002). A casecontrol study among lifetime non-smokers conducted in Chandigarh found that exposure to ETS during childhood was strongly associated with lung cancer (odds ratio (OR)=3.9; 95% CI: ). No increased risk was found with exposure to a smoking spouse who smoked bidi or chillum, but for those married to cigarette smokers, the odds ratio was 5.1 (95% CI: ). A weak association was seen with exposure to ETS at the workplace, which rose with the number of years of exposure. Exposure to ETS in vehicles was also a risk factor for lung cancer in non-smokers (Rapiti et al, 1999). VIII. STOMACH CANCER In a case-control study with matched cases and controls on cancer of the stomach from Chennai, the odds ratio for bidi smoking was 3.2 (95% CI: ) and that for cigarette smoking was 2.0 (95% CI: ). Dose response trends for smoking were highly significant for age at starting and lifetime exposure. The odds ratio for tobacco chewing was slightly elevated but not significant for stomach cancer (Gajalakshmi and Shanta, 1996). IX. ORAL SUBMUCOUS FIBROSIS Oral submucous fibrosis (OSF) is a debilitating, potentially cancerous oral condition, caused primarily by chewing areca nut and its mixtures, as demonstrated by numerous epidemiologic studies and other corroborative evidence (Murti et al., 1995). The condition may sometimes extend beyond the mouth to the oesophagus (Misra et al., 1998). The intense marketing of industrially manufactured products containing areca nut and tobacco has considerably increased the occurrence of OSF in Indian population. In three recent case-control studies, in Bhavnagar, Gujarat, Nagpur, Maharashtra and New Delhi, over 70% of the cases were under 35 years of age (Gupta et al., 1998; Hazare et al., 1998; Shah and Sharma, 1998). In the Delhi and Nagpur studies, which reported on frequency and duration of chewing, frequency rather than the total duration of the habit was directly correlated to OSF (Hazare et al., 1998; Shah and Sharma, 1998). In an earlier study from Pakistan, duration of the habit was also significant (Maher et al., 1994). Chewers of pan masala, with or without tobacco, develop the condition in about half the time as betel quid or areca quid chewers, with 75% of the pan masala chewers developing the disease within 4.5 years and quid chewers in about 9.5 years. The absence of betel leaf in pan masala and the proportionate higher dry weight of areca nuts is said to be responsible for the earlier development of OSF in pan masala chewers (Shah and Sharma, 1998). Tobacco in areca nut mixtures, although not a causative factor for OSF, is believed responsible for a higher occurrence of OSF due to its effect of increasing addiction and thereby exposure to areca nut chewing. The high malignant potential of OSF is well established (Murti et al, 1985). In a cohort study of tobacco users, the relative risk of malignant transformation in the oral mucosa of OSF patients compared to tobacco users without any precancerous lesion or condition was (Gupta et al. 1989). Increased occurrence of OSF in the younger age groups has given rise to the suspicion that oral cancer would develop faster in such patients. This has been confirmed by the demonstration of a significant increase in the incidence of oral cancer from population based cancer registry data and has been causally linked to the consumption of gutka (Gupta, 1999). X. IMPACT ON THE HEALTH ECONOMY A. Financial Costs In a study on costs of tobacco related cancers for the ICMR, the direct medical and non-medical costs, like travel and lodging, and indirect costs, like loss of income during treatment and premature death, were assessed. A cohort of 195 cancer patients was followed for three years from The average total cost per cancer patient, discounted at the 1999 level, amounted to Rs. 350,000, with direct costs amounting to 13% of total cost. Curative intent of treatment was associated with higher expenditures. The cost of the total tobacco related cancers diagnosed in India in 1999, as 87

4 estimated for this study, amounted to Rs. 57,225 billion (ICMR, 2001). It needs to be recognized that tobacco causes a proportion of many other diseases in even larger numbers than cancer. Thus, similarly, cost information was collected for one year on patients of two other major diseases for which tobacco use is a risk factor: coronary artery disease (CAD) and chronic obstructive lung disease (COLD). Conservative relative risk estimates from epidemiological studies conducted in India (2 to 3 fold for CAD and 4 fold for COLD) were used to estimate the number of prevalent cases in 1999 attributable to smoking: 4.45 million CAD cases and 39.2 million cases of COLD. The costs were estimated as Rs billion for CAD and Rs billion for COLD. During 1999, these three major diseases together were estimated to cost the country Rs billion (ICMR, 2001). In comparison, in 1998, total excise revenues from tobacco corresponded to Rs billion, and the nationwide sale value of all tobacco products was Rs. 244 billion (ICMR 2001; Price Waterhouse, 2000). Clearly the economic benefit of tobacco to the country is unable to outweigh the costs accrued due to the diseases it causes. B. Premature Mortality Due to Tobacco Apart from financial cost, the risk of premature death is higher in tobacco users than in non-users. Results of three cohort studies (two rural and one urban) have shown that tobacco users experience a significantly higher all-cause mortality compared to nonusers. In the two studies in rural areas of Ernakulam District in Kerala and Srikakulam District in Andhra Pradesh, the age adjusted relative risks for overall mortality for tobacco use by men and women ranged between 1.3 and 1.9, with smokers showing higher risks (Gupta, 1989). In a large cohort study in the city of Mumbai, the relative risk in men ranged from 1.2 in smokeless users to 1.8 for bidi smokers. The risk of women, who were mainly smokeless users, was 1.35 (Gupta and Mehta, 2000). In a retrospective study conducted in Chennai, the relative risk of death in men for smoking was 2.1 (Gajalakshmi and Peto, 2002). Based on the rural cohort studies, it was estimated that about 630,000 deaths, i.e. 12.6% of overall deaths, were attributable to tobacco use in India in 1986 (Gupta, 1989). A revised estimate for 1996 brought the number to (ICMR, 2001). Incorporating the more recently obtained information will further increase the estimated number of deaths attributable to tobacco use. C. Anti-tobacco Interventions Risk reduction The above evidence points to the possibility of preventing cancer by avoidance, cessation and reduction of tobacco use. In fact, several longitudinal studies have shown that the risk of lung cancer for cigarette smokers who stop smoking falls slowly until reaching the level of risk of nonsmokers after 10 or more years (IARC, 1986). Researchers in India believed the same would be true of oral cancer and other cancers for chewers and smokers. Several large community intervention studies have been conducted in India to assess the effectiveness of various communications strategies in persuading individuals to reduce or give up their habits. Some of these studies were also evaluated in terms of the regression of oral precancerous lesions in those who stopped using tobacco, as an indicator of reduction in oral cancer risk. D. Community Interventions: A large, controlled, educational intervention trial in tobacco users in Kerala, Andhra Pradesh and Gujarat with ten years of annual follow-up, was conducted during Messages imparted through personal communication were reinforced by documentaries, slides, posters, exhibitions, folkdramas, radio messages and newspaper articles (Gupta et al. 1986a). The educational intervention was helpful in reducing tobacco use and in significantly increasing quit rates in two areas (Ernakulam, Kerala and Srikakulam, Andhra Pradesh), assessed after five and ten years of follow up (9% and 14.3% in Ernakulam and 17% and 18.4% in Srikakulam). This resulted in substantial reduction in the incidence rates of leukoplakia, a well-established precancerous lesion, to only 40-60% of the incidence rate in the intervention area, with the smoking group a having higher level of reduction than the chewing group (Gupta et al, 1992). Within the intervention area the incidence rates of oral lesions were lower among those who gave up their habits (Gupta et al, 1995). These results underscored the great potential for primary prevention of oral cancer and other tobacco related diseases through cessation of tobacco use. In a similar intervention study conducted in rural Karnataka, the quit rates after 5 years of intervention in men and women respectively were 26.5% and 36.7% compared to 1.1% and 1.5% in a control cohort (Anantha et al, 1995). 88

5 The feasibility of using schoolchildren to bring about reduction in tobacco use in the community was examined in a State-wide intervention study in Goa. After receiving health education on tobacco and training in intervention methods, schoolchildren were instrumental in inducing a stoppage rate of 9.7% among adults in the intervention community compared to 6.1% in control community. The attitudes of children in both areas, assessed by questionnaires two years later, indicated that the intervention had been able to make a difference in children s attitudes towards tobacco (Vaidya et al., 1992). E. Mass media intervention In 1990, information about the dangers of tobacco was broadcast on All India Radio (the only radio medium at that time), through 30 Sunday morning episodes in 16 languages from 84 stations. Community surveys in Karnataka and Goa to evaluate the broadcasts, showed about 30% listenership among the potential audience in both States. In Karnataka, nearly 6% of tobacco users reported quitting the habit, as did 4.3% in Goa. Additionally, about a third of tobacco users intended to quit and another third had reduced their consumption (Chaudhry, 1994). Thus, radio communication has a proven potential for tobacco habit reduction. F. Sufficient evidence for long-term cancer risk reduction for the country. All the above evidence points to the utility of scaling up similar educational efforts through incorporating them into routine government health programmes and mass communications and requiring anti-tobacco education in school curricula. Voluntary educational efforts along these lines, too, could make a difference. G. Tobacco cessation clinics Informal tobacco cessation clinics using counselling have been in operation for a long time in India but no evaluation reports are available. The recent availability of nicotine replacement therapy, such as nicotine patches and Buproprion, has prompted several health facilities to set up tobacco use cessation clinics for people who want to quit, but are unable to do so on their own. These clinics employ pharmacological support in addition to behavioural therapy, which may include individual, group or telephone counselling, rational emotive therapy and yoga with pranayam. Early results seem encouraging (Shastri, 2003). H. Economic Interventions Economic analyses by several agencies have shown that tobacco is a net drain on an economy. Demand-side interventions such as advertising and promotion bans, smoking restrictions as well as increases in price through taxation, are all effective at reducing tobacco attributable mortality and morbidity. Measures to reduce the supply of tobacco have shown less promise in countries where they have been tried, except for the control of smuggling. Nevertheless, crop substitution may aid farmers dependent on tobacco to switch to other livelihoods (World Bank, 1999). Research in Karnataka, has suggested that appropriate interventions with tobacco farmers may persuade them to shift to the cultivation of other crops and other farm activities, like dairying (Panchamukhi, 2002). Exploratory studies with homebased women beedi workers have been conducted in several States, suggesting that alternative home-based or community-based work is likely to be accepted (International Labour Office, 2001; Dervish Trust, 2001). Additionally, phasing out government support to tobacco production, and finding substitute crops for revenue generation and export, will aid in the transition to a tobacco-free society. I. Global strategies In May, 1999, the World Health Assembly, the governing body of the World Health Organization (WHO), resolved in begin negotiations to draw up a an international legal treaty, called the Framework Convention on Tobacco Control (FCTC), that could address cross-country issues like tobacco advertising and promotion, agricultural diversification, smuggling, taxes and subsidies (WHO, 2000; Chaudhry, 2000). About 160 member nations of the United Nations have participated in the negotiations. The Convention is ready for adoption by the World Health Assembly in May Adoption by ratification of this treaty would facilitate strong tobacco control measures internationally and at the level of individual nations. J. Legislation In order to curb the use of tobacco in India, health researchers, health care providers, NGOs, lawyers and others have jointly proposed more stringent and comprehensive legislation on the advertisement, sale and use of tobacco in the country. The Tobacco Products Bill, 2001, addressing all types of tobacco products, passed through the Lok Sabha on 30th April, The bill prohibits advertising and sports sponsorship by tobacco companies. It also prohibits smoking in public places to protect nonsmokers, especially 89

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