A long-awaited study has shown that a class of aspirin-related compounds holds promise as a treatment option for multiple precancerous polyps in the colon - a condition that affects one in every hundred colorectal cancer patients.

The study, published in the New England Journal of Medicine1, "may represent a milestone in cancer prevention in humans," says cancer researcher Karin Mueller-Decker, from the Research Program Tumor Cell Regulation, Deutsches Krebsforschungszentrum, Heidelberg.

Gideon Steinback, from the University of Texas, MD Anderson Cancer Center, Houston, and colleagues found that 400 mg of a drug called celecoxib, twice daily for six months, led to a significant reduction in the number of polyps in 30 patients with Familial adenomatous polyposis (FAP), an inherited disorder of the colon and the rectum which almost always leads to cancer. Just over half of the patients receiving this dose experienced a reduction of 25% or more in the number of growths or 'polyps'. And the polyps also shrank.

To date the only treatment for FAP has been surgery. This is the first time a drug has been shown to remove at least some polyps. So what is the difference between celecoxib (dubbed 'super-aspirin' by some) and other popular 'NSAIDs' (non-steroidal anti-inflammatory drugs) such as aspirin?

NSAIDs inhibit a family of enzymes called the cyclooxygenases, or COXs. Most NSAIDs inhibit two of these enzymes - 'COX-1' and 'COX-2'. Many of the side-effects of NSAIDs including gastric ulceration and haemorrhage are a result of COX-1 inhibition. Inhibiting COX-2 does not cause these unwanted effects.

The discovery of COX-2 in tumours, along with experiments in mice showing that COX-2 itself causes polyp formation, raised the possibility that tumours could be treated by targeting COX-2 alone, avoiding the drawbacks of traditional NSAIDs. Celecoxib, although akin to an NSAID, inhibits only COX-2.

"A drug that causes polyp regression brings new hope to FAP patients and provides an important new treatment option," says Steinbach. Although he adds that "[the work] is based on the assumption that the treatment of polyps will translate into reduction in colon cancer incidence".

Makoto Mark Taketo, from the Graduate School of Pharmaceutical Sciences, University of Tokyo, agrees: "It would be very beneficial to young FAP patients if we could postpone surgery even for 5, 10 or 15 years while they are taking celecoxib, because radical operations of the colon can affect not only the quality of their lives but also their psychological development".

Patients with FAP have mutations of a gene, APC, that encodes an important regulator of cell growth. APC mutations are also responsible for the development of most sporadic colon tumours; therefore, "the finding that celecoxib is effective in FAP holds the promise that this type of medication would also be useful in the prevention of colon tumors in the general population," says Steinbach.