Protection In Gastrointestinal CancersA
DGReview of :"Effect
of anti-inflammatory drugs on overall risk of common cancer: case-control study
in general practice research
database"
BMJ
06/16/2000
By Bruce Yates
Aspirin and other anti-inflammatory drugs used in the preceding 36 months
before diagnosis appears to lower the risk of oesophageal, gastric, colon and
rectal cancers, a major British study has found.
No effect on breast,
bladder or lung cancer was found in the study. Risk of pancreatic and prostate
cancer appeared increased, although there may not be a causal relation and may
be due to chance or to undetected biases.
Findings are from a
case-controlled study among 12,174 cancer cases and 34,934 controls. Patients
had a first diagnosis of either five gastrointestinal cancers (oesophagus,
stomach, colon, rectum and pancreas) or bladder, breast, lung and prostate
cancer and for which data on prescriptions were available for a minimum of 36
months.
Researchers used the general practice research database, which
contains records on some four million British residents. It is drawn from
general practices around the country which record standard data on demography,
morbidity, prescriptions and selected other information
There is
consistent epidemiological evidence that patients who use aspirin or other
non-steroidal anti-inflammatory drugs have a lower risk of colon cancer
morbidity and mortality. How much such treatment offers protection is not clear,
although the epidemiological evidence is that mortality from oesophageal and
gastric cancer is reduced.
Consistent studies of colon cancer have shown
that up-regulation of the cyclo-oxygenase 2 (cox-2) gene in 80 per cent or more
cases, the study points out. Up regulation of cox-2 expression has been shown in
tumours of the oesophagus, stomach, and breast, but evidence of protection
against breast cancer is not certain.
The assumption that cox-2
inhibition is the critical mechanism may not be justified, although
gastrointestinal effects could reflect responses to high levels of direct drug
exposure.
Overall risk of the nine cancers was not significantly reduced
among patients who had received prescriptions in the previous 13 to 36
months.
The researchers said, however, that their findings are compatible
with the protective effects for anti-inflammatory drugs against cancer of the
oesophagus, stomach and rectum with dose related trends. There was an increased
risk of pancreatic and prostatic cancer but the level was dose related only to
pancreatic cancer.
Researchers conclude "that although aspirin and other
non-steroidal anti-inflammatory drugs may protect against gut epithelial
cancers, there may be no overall benefit from use of non-selective cox-2
inhibitors in preventing cancer. Further investigation is warranted to confirm
or refute that use of such drugs raises the risks of pancreatic and prostatic
cancers."
