The beneficial effects of smoking cessation on oral cancer incidence are seen 3 to 5 years after cessation. The difference in risk for oral cancer between former smokers and never smokers becomes insignificant after 10 to 20 years of cessation «Khalifeh M, Ginex P, Boffetta P. Reduction of head...»1, «IARC (2023). Oral cancer prevention. IARC Handb Ca...»2. The evidence for smoking cessation on oral cancer risk is based on case control and cohort studies and is upgraded two levels for large effects and dose-response gradient.
Smoking cessation advise and motivation should be targeted to all users and especially those having other risk factors or oral potentially malignant lesions.
| Reference | Study type | Population | Exposure | Outcomes | Risk of bias |
|---|---|---|---|---|---|
| «Khalifeh M, Ginex P, Boffetta P. Reduction of head...»1 | SR/MA |
Studies conducted in Europe, USA, South-America, Asia and Africa, altogether 65 studies of head and neck cancer, 24 studies of oral cancer between 1988 - 2011 | Smoking cessation compared to smoking | Oral cancer | Low |
SR=systematic review; MA=meta-analysis
| Reference | Number of studies and number of patients (I/C) | Follow-up time | Relative effect (95% CI) |
|---|---|---|---|
| Level of evidence: high The quality of evidence is upgraded due to large effects and dose-response gradient |
|||
| «Khalifeh M, Ginex P, Boffetta P. Reduction of head...»1 | 24 studies, of which 22 case-control and 2 cohort studies 20849 cases (cessation) and 84627 controls (smokers) |
3 to > 20 years | 0.46 (0.36, 0.56) the risk ratios for pharyngeal and laryngeal cancer were similar to oral cancer and therefore the effect of cessation time was calculated altogether as head and neck cancer: <5 years 0.67 (0.54, 0.82) 5 to <10 years 0.50 (0.44, 0.57) 10 to <15 years 0.37 (0.28, 0.51) 15 to <20 years 0.29 (0.25, 0.33) ≥20 years 19 0.20 (0.16, 0.25) |
E= exposure; C=comparison; CI=confidence interval
Comment: In IARC report «IARC (2023). Oral cancer prevention. IARC Handb Ca...»2 the difference in risk for oral cancer becomes insignificant between former smokers and never smokers after 10 years of cessation.