© 1999 by Oxford University Press
Journal of the National Cancer Institute, Vol. 91, No. 8, 726-728,
April 21, 1999
© 1999 Oxford University Press
CORRESPONDENCE |
Time Since Stopping Smoking and the Risk of Oral and Pharyngeal Cancers
Affiliations of authors: C. La Vecchia, Istituto di Ricerche Farmacologiche "Mario Negri," and Istituto di Statistica Medica e Biometria, Università degli Studi, Milan, Italy; S. Franceschi, R. Talamini, Servizio di Epidemiologia, Centro di Riferimento Oncologico, Aviano (PN), Italy; C. Bosetti, E. Negri, Istituto di Ricerche Farmacologiche "Mario Negri," Milan, Italy; F. Levi, Registre Vaudois des Tumeurs, Institut universitaire de médecine sociale et préventive, Lausanne, Switzerland.
Correspondence to: Carlo La Vecchia, M.D., Istituto di Ricerche Farmacologiche "Mario Negri," Via Eritrea 62, 20157 Milan, Italy.
In the largest study to date of oral and pharyngeal cancers that contained 1114 case subjects and 1268 control subjects from four areas of the United States, cessation of smoking was associated with a sharply and markedly reduced risk (1). The odds ratio (OR) for all current smokers combined was 3.4 for males and 4.7 for females. For ex-smokers (i.e., subjects who had not smoked for at least 1 year), the OR was 1.1 for males and 1.8 for females 1-9 years after smoking cessation, 1.1 for males and 0.8 for females 10-19 years after cessation, and 0.7 for males and 0.4 for females 20 years or longer after cessation.
Such a drop in risk in a relatively short time suggested that smoking mainly affects the later stages of oral and pharyngeal carcinogenesis (1) and, if confirmed, would have relevant public health implications. However, the U.S. veterans cohort study (2) showed elevated risks of oral (relative risk = 1.5) and pharyngeal (relative risk = 2.6) cancers in all former smokers combined.
To clarify the issue, we decided to assess the pattern of risk of oral and pharyngeal cancers after a person stops smoking by analyzing the combined results of two case-control studies, the first conducted in Italy (3) and the second conducted in Italy and Switzerland (4). Briefly, from 1984 through 1997, data were collected by trained interviewers on 1280 case subjects, younger than 75 years old, who had incident, histologically confirmed oral and pharyngeal cancers (638 patients with oral cancer and 642 patients with pharyngeal cancer, 1085 males and 195 females) and who were admitted to a network of hospitals in the greater Milan area and Pordenone (northern Italy), Rome and Latina (central Italy), and the Swiss Canton of Vaud. Control subjects were 4179 patients (3068 males and 1111 females) admitted to the same network of hospitals for acute, nonneoplastic conditions that were unrelated to alcohol or tobacco consumption.
Table 1
gives the distribution for the groups of patients with oral and
pharyngeal cancers and the comparison group, according to smoking status and time since
cessation. The overall multivariate OR, after allowance for study center, age, sex, education, and
alcohol drinking, was 8.4 for current smokers. Among ex-smokers, the ORs were 6.2 for those
who had stopped smoking for less than 2 years, 4.5 for those who had stopped for 3-5 years, 3.5
for those who had stopped for 6-9 years, 1.6 for those who had stopped for 10-14 years, and 1.4
for those who had stopped for 15 or more years. For oral cancer, the OR was 2.9 for those who
had stopped smoking for 6-9 years, but was no longer above unity after 10 or more years. For
pharyngeal cancer, which in Italy and Switzerland represents a higher proportion of cases than in
North America (1,2), the OR was 3.2 for those who had stopped smoking
for 10-14 years and 2.9 for those who had stopped for 15 years or longer.
|
and 95% confidence intervals (CIs) for data from Italy
and Switzerland (1984 through 1997)For ex-smokers, the relative risk of lung cancer declines with time since stopping smoking, to reach asymptotically the relative risk of never smokers, but is still above that of never smokers (i.e., subjects who had never smoked at least one cigarette per day for at least 1 year) 10 or more years after stopping (5-7). The pattern of risk for oral and pharyngeal cancers observed in this study suggests the existence of similarities in the process of carcinogenesis for these major tobacco-related neoplasms. The decrease in risk, however, may be steeper for oral cancer.
REFERENCES
1 Blot WJ, McLaughlin JK, Winn DM, Austin DF, Greenberg RS, Preston-Martin S, et al. Smoking and drinking in relation to oral and pharyngeal cancer. Cancer Res 1988;48:3282-7.cancerlit;88210327
2 McLaughlin JK, Hrubec Z, Blot WJ, Fraumeni JF Jr. Smoking and cancer mortality among U.S. veterans: a 26-year follow-up. Int J Cancer 1995;60:190-3.cancerlit;95130230
3 Franceschi S, Talamini R, Barra S, Baron AE, Negri E, Bidoli E, et al. Smoking and drinking in relation to cancers of the oral cavity, pharynx, larynx, and esophagus in northern Italy. Cancer Res 1990;50:6502-7.cancerlit;91003992
4 Talamini R, La Vecchia C, Levi F, Conti E, Favero A, Franceschi S. Cancer of the oral cavity and pharynx in nonsmokers who drink alcohol and in nondrinkers who smoke tobacco. J Natl Cancer Inst 1998;90:1901-3.cancerlit;99077464
5 Doll R. The age distribution of cancer: implications for models of carcinogenesis. J R Stat Soc A 1971;134:133-55.
6 Public Health Service, U.S. Department of Health and Human Services (DHHS). The health benefits of smoking cessation. A report of the Surgeon General, U.S. Centers for Disease Control, Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health 1990 Report No. DHHS Publ No. (CDC)90-8416.
7 Halpern MT, Gillespie BW, Warner KE. Patterns of absolute risk of lung cancer mortality in former smokers. J Natl Cancer Inst 1993;85:457-64.cancerlit;93188050
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||