A new study in the journal Tumor Biology has found that a combination of fish oil and celecoxib, a COX-2 inhibitor, is more effective in suppressing the development of breast cancer than either substance alone. In the study, the combination of fish oil and celecoxib inhibited the growth of breast cancer cells and the development of mammary hyperplasia, a precursor of breast cancer, much more strongly than aspirin or fish oil separately. COX-2 is a known stimulant of both tumor growth and angiogenesis. Suppressing COX-2 with food represents a natural, non-toxic way to reduce cancer risk and warrants further study.

Cyclooxygenase (COX-2), an enzyme produced by the body in response to inflammation, is a target of non-steroidal anti-inflammatory drugs (NSAIDs), which include the popular pain medications aspirin, ibuprofen, and celecoxib (Celebrex). Increased COX-2 production and inflammation are linked to the development of a number of cancers. Suppression of COX-2 through the use of NSAIDs has therefore emerged as a potentially powerful form of chemoprevention.

Celecoxib, which specifically targets COX-2, has been shown to suppress both tumor growth and new blood vessel growth (angiogenesis). Previous research has also shown that substances naturally found in fish oil called n-3 polyunsaturated fatty acids (PUFAs) suppress the transformation of normal cells to cancerous ones by inhibiting COX-2.
Researchers at Panjab University, Chandigarh, India used a rat model of breast carcinogenesis to test whether the combination of a COX-2 inhibitor and fish oil was more effective for suppressing cancer development than either substance alone. They administered a known mammary carcinogen (DMBA) to female rats and then gave them celecoxib plus fish oil at one of two doses: 20 mg/kg body weight + 0.5 ml or 30 mg/kg body weight + 0.25 ml. Control mice were treated with fish oil or celecoxib only. The treatment was given for 7 days.
Results showed that pretreatment with celecoxib plus fish oil led to a marked reduction in a number of biomarkers for breast carcinogenesis—an effect that was more pronounced than with celecoxib or fish oil alone. There was also a much greater reduction in mammary hyperplasia, a precursor of breast cancer development, in rats that received both agents. In fact, rats that got the combination therapy had a return to normal mammary tissue from hyperplasia.
Of interest, the higher celecoxib dose was no more effective than the lower dose, suggesting that, if combined with fish oil, a lower dose of celecoxib could be used for chemoprevention. Separately, British researchers are initiating a prospective study of aspirin plus another ingredient in fish oil called eicosapentaenoic acid (EPA) in people with a history of precancerous colon polyps. The objective of the study is to determine whether the combination of aspirin and EPA is more effective at preventing colon polyps than either agent alone.