Epidemiological studies show that non-steroidal anti-inflammatory drugs (NSAIDs) reduce colorectal cancer incidence.
We measured the rate ratio for colorectal adenocarcinoma according to dosage and the timing of exposure by means of a case-control study, nested in a non-concurrent cohort linkage study, using the population of beneficiaries of the Saskatchewan Prescription Drug Plan from 1981 to 1995 with no history of cancer since 1970 as the source population.
Four controls per case, matched on age and gender and alive when the case was diagnosed, were randomly selected.
Dispensing rates, calculated over successive time periods, characterized NSAID exposure.
We accrued 3844 cases of colon cancer and 1971 cases of rectal cancer.
For colon cancer a significant trend towards a decreasing rate ratio was associated with increasing exposure during the 6 months preceding diagnosis (P-trend=0.002).
For both cancers, significant trends were associated with exposure 11-15 years before diagnosis (colon : P-trend=0.01 ; rectum : P-trend=0.0001).
At the highest exposure levels the rate ratio for colon cancer was 0.57 (95% confidence interval (CI) 0.36-0.89) ; for rectal cancer it was 0.26 (95% Cl 0.11-0.61).
No protection was associated with exposure during other periods.
The timing of NSAID use must be considered in planning intervention trials to prevent colorectal cancer.
There may be a 10-year delay before any preventive effect will appear.
Mots-clés Pascal : Adénocarcinome, Côlon, Rectum, Antiinflammatoire non stéroïde, Anticancéreux, Facteur risque, Epidémiologie, Posologie, Timing, Chimioprophylaxie, Prévention, Etude cas témoin, Saskatchewan, Canada, Amérique du Nord, Amérique, Homme, Tumeur maligne, Côlon pathologie, Rectum pathologie, Intestin pathologie, Appareil digestif pathologie
Mots-clés Pascal anglais : Adenocarcinoma, Colon, Rectum, Non steroidal antiinflammatory agent, Antineoplastic agent, Risk factor, Epidemiology, Posology, Timing, Chemoprophylaxis, Prevention, Case control study, Saskatchewan, Canada, North America, America, Human, Malignant tumor, Colonic disease, Rectal disease, Intestinal disease, Digestive diseases
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0429056
Code Inist : 002B02R02. Création : 22/03/2000.