Effect of aspirin and non-steroidal anti-inflammatory drugs on colorectal adenomas: case-control study of subjects participating in the Nottingham faecal occult blood screening programme.

OBJECTIVE

To examine the relation between the use of aspirin and non-steroidal anti-inflammatory drugs and the presence of asymptomatic colorectal adenomas.

DESIGN

Case-control study of subjects participating in a randomised controlled trial of faecal occult blood screening for colorectal cancer. Data on analgesics and other drugs were obtained from a questionnaire which was mainly concerned with diet and was administered by an interviewer.

SETTING

Nottingham.

SUBJECTS

147 patients with positive results in faecal occult blood tests who were found to have colorectal adenomas (cases), 153 age and sex matched control subjects with negative results in such tests (negative controls), and 176 control subjects with positive results in the tests who were found not to have colorectal adenomas (positive controls).

MAIN OUTCOME MEASURES

Relative risk of developing colorectal adenomas according to frequency and duration of use of analgesics.

RESULTS

Cases reported taking less aspirin and non-steroidal anti-inflammatory drugs than the negative controls, with the estimated relative risk for any use being 0.49 (95% confidence interval 0.3 to 0.8). The inverse association was less strong when cases were compared with the positive controls (0.66 (0.4 to 1.1)). The association was specific for aspirin and non-steroidal anti-inflammatory drugs there being no association with paracetamol or other drugs. Prescribed use of non-steroidal anti-inflammatory drugs for longer than five years was associated with the lowest risk (0.21 (0.1 to 0.8)), although the numbers reporting prolonged prescribed use were small.

CONCLUSIONS

These findings support the hypothesis that aspirin and non-steroidal anti-inflammatory drug use protects against the development of colorectal neoplasia.