Daily aspirin may prevent the incidence of cancer in individuals who are genetically predisposed to hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch Syndrome, according to the results of a study presented September 21, 2009 at Europe’s largest cancer congress, ECCO 15-ESMO 34, in Berlin.
Hereditary nonpolyposis colorectal cancer (HNPCC) is a genetic syndrome caused by mutation in one of several genes. HNPCC accounts for about 3-5% of all colorectal cancer. These mutations greatly increase the risk of developing colorectal cancer. In fact, individuals who carry the mutation have an 80% lifetime risk of developing colorectal cancer. In individuals with an HNPCC mutation, the average age at diagnosis of colorectal cancer is 44 years compared with 64 years in the general population. In addition, other cancers are more common in families that carry this mutation, including cancers of the endometrium (the lining of the uterus), ovary, small intestine, ureter, and renal pelvis.
Some research has indicated that aspirin may have a protective effect for individuals with HNPCC; however, other studies have indicated that it does not. Now, researchers are speculating that long-term use of aspirin might be the key to receiving benefit.
A clinical trial involving 1,071 individuals with the HNPCC mutation in 42 centers worldwide randomized patients to receive a daily dose of aspirin plus Novelose (a resistant starch that escapes digestion) or Novelose alone. Early results of the study indicated no evidence of benefit from aspirin; however, the results began to change about four years after initiation of the study, and the incidence of cancer began to vary between the two groups. To date, six patients in the aspirin group have developed colon cancer compared with 16 patients in the placebo group. The researchers also noted a reduction in the incidence of endometrial cancer.
The researchers observed that these results are statistically significant and also noted that patients stopped taking aspirin after four years, thus suggesting that the benefits continue even after discontinuation of the aspirin. There were fewer strokes and heart attacks in the aspirin group.
Eleven patients in the aspirin group experience side effects including gastrointestinal bleeds or ulcers compared with nine patients in the placebo group.
The researchers concluded that long-term aspirin use provides benefit to individuals with HNPCC mutations. Future research will be directed toward evaluating the effects of a lower dose of aspirin.
 Burn J, Gerdes AM, Mecklin JP, et al. Aspirin prevents cancer in Lynch syndrome. European Journal of Cancer Supplements, Vol. 7, No. 3, September 2009. Abstract O-6000.
 Jacobs E, Thun M, Bain E, et al. A large cohort study of long-term daily use of adult-strength aspirin and cancer incidence. Journal of the National Cancer Institute. 2007; 99: 608-615.
 Burn J, Bishop T, Mecklin JP, et al. Effect of aspirin or resistant starch on colorectal neoplasia in the lynch syndrome. New England Journal of Medicine. 2008; 359: 2567-2578.