Confirming the findings from animal studies, treatment with SSRI type antidepressants, such as Zoloft and Prozac, is associated with a decreased risk of colorectal cancer, new research shows.

By contrast, the study did not show a link between tricyclic antidepressant use and the increased tumor risk previously seen in laboratory studies.

As reported in The Lancet Oncology, Dr. Jean-Paul Collet, from Sir Mortimer B. Davis Jewish General Hospital in Montreal, and colleagues compared antidepressant use in patients with or without colorectal cancer. For the tricyclic antidepressant analysis, 6,544 colorectal cancer patients and 26,176 comparison subjects were included, while the SSRI analysis involved 3,367 cancer patients and 13,468 comparison subjects.

Patients who took high daily doses of SSRI antidepressants in recent years cut the risk of colorectal cancer by 30 percent compared with those who did not use this drugs. By contrast, high daily doses taken many years ago did not have a significant effect on risk.

As noted, tricyclic antidepressant use did not significantly affect the risk of colorectal cancer, the report indicates.

“To our knowledge, this is the first epidemiologic study to report an association between SSRI use and reduced risk of colorectal cancer,” Collet’s team states. “Despite the usual limitations of administrative databases, we think that this association is important and worth further investigation.”

Dr. Henrik Toft Sorensen, an editorialist from Aarhus University Hospital in Denmark, comments that the new findings “provide interesting insights, but until data are available, clinicians should not consider SSRI use solely” because they might prevent colorectal cancer.

SOURCE: The Lancet Oncology, April 2006.