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Cancer Prevention: Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

Types of NSAIDs
COX-1 Inhibitors:
Structure of Acetaminophen, Structure of Diclofenac, Structure of Ibuprofen, Structure of Salicylic Acid

COX-2 Inhibitors:
Structure of Celecoxib, Structure of Naproxen, Structure of Rofecoxib, Structure of Valdecoxib

Intro and Background
The inflammatory response is a normal function of the human immune system. This process helps repair the body after injury. When you get cut or hurt, the area usually becomes red, hot, and swollen. In part, this is caused by the immune system as it works to heal the damaged area of your body. This response brings nutrient rich blood to the area so injured tissues can be repaired and new cells can grow . Despite its normally positive function, research has shown that the human inflammatory response is important in controlling the environment of cancer cells. Inflammation can promote tumor angiogenesis, initiation, growth and metastasis. Cells of the immune system, such as macrophages, may also be negatively affected by inflammation. . Also, the same cells that are stimulated by the immune response to grow and replicate may malfunction and grow without proper regulation; this behavior may lead to the initiation of a cancerous growth. .

Learn MORE about angiogenesis and metastasis

Non-steroidal anti-inflammatory drugs interfere with the activity of a family of enzymes called cyclooxygenases (COX). COX inhibitors prevent the enzymes from producing chemical signals responsible for inflammation, pain and possibly tumor growth . There are two types of NSAIDs, grouped by the form of COX they inhibit (COX-1 or COX-2). NSAIDs are quite common and are commonly known as pain relievers [acetaminophen (Tylenol®), diclofenac (Voltaren®), ibuprofen (Advil® ), salicylic acid (Aspirin®), celecoxib (Celebrex®), naproxen (Aleve®), rofecoxib (Vioxx®), and valdecoxib (Bextra®)]. Aspirin is also taken for the prevention of heart disease. For this use, the average, safest, and most effective dose of aspirin usually recommended by doctors is 81 mg/day .

Scientific Research
Much research suggests that NSAIDs are effective chemopreventative agents but significant negative effects have also been identified. Regular use of aspirin has shown to reduce the risk of colorectal cancer as well as recurrent colorectal cancer in humans . Exactly how these drugs reduce cancer risk is still unclear but seems to be linked to their COX enzyme inhibition activity .

COX-1 inhibitors are associated with digestive problems such as excessive bleeding and ulcers .

COX-2 inhibitors have recently come under scrutiny because they were identified as increasing the risk of heart attacks and strokes . Because of the risks that are also associated with NSAIDs, only people at high risk of cancer are recommended by their doctors to take these drugs as a preventative measure. Researchers are now working to identify the sub-population of people who should take NSAIDS to lower their risk of colon cancer .

For information about ongoing clinical trials involving NSAIDs, please visit our section on Finding Clinical Trials.

US Food and Drug Administration Approval
Celecoxib (Celebrex®) is the only NSAID that has been approved to treat cancer. It is used to reduce polyps for people with a rare genetic disorder (adenomatous polyposis).