Second Chapter
Dr. Álvaro Monterrosa Castro, MD
An Italian study (125) has documented a 37% reduction in the risk of colorectal cancer, associated with the use of combined oral contraceptives. OR: 0.63 (CI: 0.45 – 0.87), protection that increases with increasing duration of use.
Martínez et al (126), using the Nurses Health Study database, report a 40% decrease in the risk of colon cancer among women who have used contraceptive pills for ninety-six months, finding when comparing them with non-users an RR: 0.6 (CI : 0.4 – 0.89).
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A recent publication (10) points out the publication of a meta-analysis that allowed establishing in women users of oral contraception, an OR: 0.82 (CI: 0.74 – 0.93), which allows us to corroborate that epidemiological studies have been emphasizing the role of oral contraceptives on the prevention of the development of colorectal cancer.
As an explanation, the hypothesis has been raised of the changes that estrogen induces in the synthesis and excretion of bile, as well as in the reduction in the concentration of bile in the colon. The favorable effects of combined oral contraceptives extend to adenomatous polyps and colonic premalignant lesions.
A review (43) points out that until 1998, three of four cohort studies and five of eleven case-control studies emphasized that users of combined oral contraceptives had a reduced risk of colorectal cancer.