Is it possible something simple like aspirin and related drugs could work in preventing and treating cancer?

Recently, the role of NSAIDs (non-steroidal anti-inflammatory drugs) was reviewed by Michael Thun, MD, and S. Jane Henley, MSPH, from the American Cancer Society in Atlanta, and Carlo Patrono from the Center of Excellence on Aging in Chieti, Italy, in the Journal of the National Cancer Institute (Vol. 94: 252-266).

What is known, according to the report, is that several studies have shown that NSAIDs can lower the risk of cancer in the colon and rectum. These drugs may also cause colon polyps to reduce their size and number in a rare condition called familial adenomatous polyposis (FAP).

But, as noted in the review, there are still many questions that need to be answered. These questions include issues such as the safety of these drugs, especially when used on healthy people to prevent cancer. Experts want to know how they really work, and what is the best dose to use.

On the prevention side, experts are asking how to conduct studies to prove where these NSAIDs have the most effect. These studies would involve looking at many people over many years. Lots of people have to be treated to find out whether or not any drug will decrease the number of cancers in a group.

Also, people taking the prevention medicine should be otherwise healthy. So, if there is any harm, it means the medicine would be hurting healthy people. This is something that needs to be avoided when trying to prevent any disease.

Why might these drugs work in cancer? The reasons are very complex, but have to do with the fact that NSAIDs can block a certain enzyme that normally appears in increased amounts in the body in response to inflammation. In certain cancers, there are increased amounts of this enzyme.

Some of the NSAIDs, like aspirin, are very general in blocking this enzyme; other newer drugs, called COX-2 inhibitors, are more targeted in their attack on the enzyme.

Two things may happen to cancer cells exposed to these drugs:

• the drugs may cause cancer cells to undergo a process of normal cell death called apoptosis;
• they may also block new blood vessels from forming, called anti-angiogenesis, which the tumor needs to continue growing.

Other studies are looking at the role of these drugs in treatment of precancerous lesions of the mouth, esophagus, and skin according to the authors. They also note that adjuvant, or preventive, trials are testing whether these drugs prevent a treated cancer from recurring. These cancer trials include bladder cancer, metastatic breast cancer, and localized prostate cancer.

The report concludes with the caution that "unresolved questions about the mechanism(s) by which these drugs act, the optimal drug, dose, treatment regimen, and the balance of risks and benefits in specific populations must be answered."

The second report on the role of COX-2 inhibitors — the targeted enzyme blocker — appeared as a news article in the same journal. It notes that "today, experts are optimistic that the drug may prove useful for cancer treatment as well."

This report describes clinical trials already underway using COX-2 inhibitors for the prevention of colorectal, oral, skin, esophageal, and non-small-cell lung cancers. Studies are also looking at these drugs in the treatment of cervical, prostate, and metastatic breast cancers.

These drugs also, in mouse studies, increase the effect of standard chemotherapy drugs. This may turn out to be very useful for patients who receive chemotherapy drugs. They may also help improve radiation therapy by making cancers more sensitive to radiation, according to the article.

What all of this shows is that sometimes there are benefits from drugs that no one knew about when the drug was first developed. Scientists are always on the lookout for other uses for the drugs we use every day, like aspirin.