Tobacco Related Cancers Philip C. Nasca, MS, PhD, FACE State University of New York At Albany School of Public Health
Annual Deaths Attributable to Cigarette Smoking – United States, 200-2004
Assessing Causality • Strength of Associations: There are mathematical techniques for measuring how strongly two variables are associated, to be discussed later in the course. Strong associations are more likely to be causal than weak associations; but the fact that an association is weak does not rule out a causal association • Consistency: Repeated observation of an association in different populations, at different times, using different methodologies • Biologic Credibility (Plausibility):An assessment of how credible the inference is, based on available biologic evidence
Assessing Causality • D. Temporality (Time Sequence): The necessity that cause precede effect in time. This is a necessary part of causal inference, but sometimes temporal information is not available. • Biologic Gradient (Dose-Response Relationship): The observation of a gradient of risk associated with the degree of exposure. • F. Experimental Evidence: Strong, but such information is seldom available for human populations. Animal data are often used, e.g. to test if a particular substance may be carcinogenic and then these data are used by analogy, to support observational data that the substance is associated with cancer in humans.
Assessing Causality G. Coherence: Agreement between the hypothesized cause and the known facts of the natural history and biology of the disease. Very similar to “biologic credibility”. H. Analogy: A very weak criterion since an analogy with a different causal association may not pertain to the association in question. Good for hypothesis generation. I. Specificity: Of historic and pedagogic interest only. This criterion states that one cause should lead to a dingle, not multiple effects. This has been advanced by many others (Koch-Henle postulates of infectious disease), but, even with reservations, it appears obvious that single events/causes/exposures can have many effects.
Risks For Cancers of The Upper Digestive and Respiratory Tracts in Male Smokers Relative to That of Nonsmokers Who Drink Little of No Alcohol Example – Cancer of the Larynx Wynder et al. (1976)
Risks For Cancer of the Pancreas in Cigarette Smokers Relative to That For Nonsmokers – Wynder et al. (1983)
Risk for Cancer of the Hypolarynx/Epilarynx According to Daily Consumption of Tobacco and Alcohol – Tuyns et al (1988). Alcohol Consumption (g Ethanol/day) *Risk Relative To Those Who Consume 0-40g ethanol/day and 0-7 g tobacco/day
Table 15. Risks for cancer of the bladder of male cigarette smokers relative to those for nonsmokers - Examples *Ratio between the occurrence rate of cancer among smokers and that among nonsmokers
Figure 7-7. Table of concentrations of selected compounds in nonfilter cigarette mainstream smoke (MS) and the ratio of their relative distribution in sidestream smoke (SS):MS* - Examples MSSS:MS Vapour Phase Carbon Monoxide 10-23 mg 2.5-4.7 Benzene 12-48ug 10 Formaldehyde 70-100 ug 8-15 Particulate Phase Nicotine 1.7-3.3 1.8-3.3 2-Naphthylamine 1.7ng 30 Benzopyrene 20-40 2.5-3.5
Range of Average Indoor Concentrations of Noteable ETS Contaminants Associated With Smoking Occupancy
Figure 3-16. Urinary cotinine concentrations by number of reported exposures to tobacco smoke in the past 4 days among 663 nonsmokers, Buffalo, New York, 1986 Number of Exposures in the Past 4 Days
HISTORY OF SMOKELESS TOBACCO Smokeless tobacco was used in the United States in the early 1600s when snuff made its way to the Jamestown Colony in Virginia through the efforts of John Rolfe in 1611 (1). Evidence of tobacco chewing, however, was not until a century later in 1704 (2).
A Chinese Law in 1683 Threatened That Anyone Possessing Tobacco Would Be Beheaded
HISTORY OF SMOKELESS TOBACCO • In the past, tobacco use was considered by some as beneficial. • 3500 B.C. tobacco an article of value – Mexico and Peru • Alleviation of hunger pains • Medicinal Uses: In Native Americans – to alleviate toothaches, disinfect cuts and relieve the effects of snake, spider, and insect bites • 19th and 20th centuries used to relieve toothache, to cure neuroglia, bleeding of gums, and scurvy • To preserve and whiten teeth and prevent decay
CHEWING TOBACCO • Looseleaf • Plug • Twist • SNUFF • Moist • Dry
Does smokeless tobacco cause cancer? • Smokeless tobacco is tobacco that is not burned. It includes chewing • tobacco, dip, snuff, and betel quid*. • At least 28 chemicals in these products have been found to cause • cancer, including: • Esophageal cancer • Mouth cancer • Pancreatic cancer • Esophageal cancer • Lip cancer • Mouth cancer • Pharynx cancer • Tongue cancer • *Betel quid is a combination of betel leaf, areca nut, and slaked lime. In many countries, • tobacco is added, and the product is known as gutka, ghutka, or gutkha. Like other smokeless • tobacco products, betel quid and gutka are known to cause various cancers
Table 9-3 Cancer sites for which there is “sufficient” evidence of carcinogenicity of tobacco smoking according to the International Agency for Research on cancer
Figure 9-12. Unless current smokers quit, tobacco deaths will rise dramatically in the next 50 years IMPACT OF TOBACCO ON GLOBAL HEALTH