Effects of Smoking Cessation
Counseling and Smoking Cessation
Drug Treatment and Smoking Cessation

Note: A separate PDQ summary on Levels of Evidence for Cancer Screening and Prevention Studies is also available.

The summaries in the Cancer Prevention section of the PDQ refer to cancer prevention, defined as a reduction in the incidence of cancer. The PDQ includes summaries generally classified by histological type of cancer, especially when there are known risk factors for the specific types of cancer. This summary addresses a specific risk factor, tobacco use, which is associated with a large number of different cancers (and other chronic diseases), and unequivocally contains human carcinogens.[1] The focus of the summary is on clinical interventions by health professionals, that decrease the use of tobacco.

Based on good evidence, cigarette smoking causes various cancers, including, but not limited to lung cancer. Smoking avoidance and smoking cessation results in decreased incidence and mortality from cancer.

Levels of Evidence

A. Study Design: (Level of Evidence 3)

3: Evidence obtained from cohort or case-control studies.

B. Internal Validity: Good.

C. Consistency: Good.

D. Direction and Magnitude of Effect: The relative risk of several cancers is statistically greater than 1 in populations exposed to tobacco.

E. External Validity: Good.

Based on good evidence, counseling by a health professional improves smoking cessation rates.

Levels of Evidence

A. Study Design: (Level of Evidence 1)

1: Evidence obtained from randomized controlled trials.

B. Internal Validity: Good.

C. Consistency: Fair.

D. Direction and Magnitude of Effect: Counseling improves cessation rates by approximately one third.

E. External Validity: Good.

Based on good evidence, drug treatments, including nicotine replacement therapies (gum, patch, spray, lozenge, and inhaler) and antidepressant therapy (e.g., bupropion), result in better smoking cessation rates than placebo.

Levels of Evidence

A. Study Design: (level of Evidence 1)

1: Evidence obtained from randomized controlled trials.

B. Internal Validity: Good.

C. Consistency: Fair.

D. Direction and Magnitude of Effect: Treatments, alone or in combination, improve cessation rates over placebo by a minimum of approximately 10% after 6 months.

E. External Validity: Fair.

References

1. Tobacco smoking. IARC Monogr Eval Carcinog Risk Chem Hum 38: 35-394, 1986.  [PUBMED Abstract]
   
   

Back to Top

Next Section >