Does aspirin or ibuprofen protect against colorectal cancer?
Both aspirin and ibuprofen are associated with a lower risk of colorectal cancer, but the side effects are serious enough that you should not start using them preventively without first consulting your doctor.
Aspirin noticeably reduces the risk of colorectal cancer. A review of 91 epidemiological studies shows that daily use is associated with roughly 63% lower odds of developing colorectal cancer. A large case-control study confirmed this: even at 75 mg per day, after at least five years of use, a clear protective effect was visible. The effect grows stronger the longer someone uses the drug.
Ibuprofen shows a similarly protective pattern. Multiple studies find a lower risk of colorectal cancer and of polyps, the early precursors of that cancer. A large screening study confirmed the protection against polyps. Notably, in overweight women the effect appeared to disappear, while men still benefited even at higher body weight. Researchers do not yet know why this is the case.
Not every drug works equally well. Aspirin at a low dose of 81 mg per day and paracetamol showed no protective effect in one study. Paracetamol barely inhibits a particular inflammatory enzyme (COX-2), and that enzyme appears to be crucial for the protective effect. This suggests that sufficient suppression of that enzyme is necessary.
For survival after a colorectal cancer diagnosis, long-term use of aspirin or ibuprofen makes no difference. That conclusion is based on one large study, but the result is clear: prior use does not appear to improve the prognosis after diagnosis.
The major stumbling block is safety. Regular use of aspirin or ibuprofen raises the risk of brain bleeds and gastrointestinal bleeds. Experts therefore conclude that a general preventive recommendation for people without an elevated colorectal cancer risk cannot be justified. The optimal dose and duration of use have not yet been established. If you are considering using aspirin or ibuprofen preventively, discuss this with your doctor first, especially if you have an elevated bleeding risk.
This answer is based on a review of 91 epidemiological studies, several large case-control studies, and a large screening study. All of this research is designed as comparative observational research: people who were already using aspirin or ibuprofen were compared with people who were not. Cause and effect therefore cannot be fully proven, but the pattern is consistent and the researchers consider a causal relationship plausible. Only one study is available on sex differences and genetic influences, so the conclusions there are weaker.
Does eating a high-fibre diet help protect against colorectal cancer?
Eating more fibre is consistently associated with a lower risk of colorectal cancer, with whole grains having the strongest supporting evidence. Try to eat wholegrain bread, oats or legumes every day as a concrete step.
Does bowel cancer screening really help (less mortality)?
For people aged 45 to 75 with average risk, colorectal cancer screening is worthwhile and widely recommended. It demonstrably reduces the likelihood of developing colorectal cancer, although the evidence for short-term mortality reduction is less definitive than previously thought.
Does eating processed meat such as sausage and ham give me colorectal cancer?
Eating a lot of processed meat measurably raises your risk of colorectal cancer by around 18-21%. Eating less sausage and ham, combined with more fibre, is the most evidence-backed step you can take yourself.
Do lycopene and tomatoes protect against prostate cancer?
The association between tomatoes, lycopene, and lower prostate cancer risk is plausible, but not yet proven firmly enough to justify specific supplement recommendations. Tomatoes as part of a varied diet is a sensible choice; taking lycopene in isolation has no proven added value at this time.
Does fasting or intermittent fasting help prevent cancer?
There is no evidence that fasting prevents cancer in humans; the animal results are promising but contradictory. If you want to address excess weight as a way of reducing risk, intermittent fasting can be a tool for that, but do not expect a direct cancer-preventive effect.
Does using the contraceptive pill increase my risk of cancer?
The pill demonstrably lowers the risk of ovarian and uterine cancer, but slightly raises the risk of breast cancer with long-term use or use before a first pregnancy. Discuss your personal situation with your GP or gynaecologist if you have any doubts.