At the same time, oral contraceptive use is associated with a short-term increased risk of breast cancer after discontinuation, although the lifetime risk of breast cancer is not significantly different, the researchers found.
The absolute risk of breast cancer after discontinuation is “extremely small” and should be a limited factor when deciding whether to start oral contraceptive pills (OCPs), a doctor said.
The study was conducted by Torgny Karlsson, PhD, a researcher in the department of immunology, genetics, and pathology at Uppsala (Sweden) University, and colleagues and published online in Cancer Research.
Reinforcing and extending knowledge
“These findings are generally consistent with what is known, but extend that knowledge, most notably by the longer-term follow-up for the cohort,” commented Nancy L. Keating, MD, MPH, professor of health care policy and medicine at Harvard Medical School and a physician at Brigham and Women’s Hospital, both in Boston. “Other studies have also shown that OCPs lower risk of ovarian and endometrial cancer. This study suggests that this protective benefit extends up to 30-35 years after discontinuing OCPs.”
Dr. Nancy L. Keating
The results “reinforce the message to patients of the protective effect of OCPs on risk of ovarian and endometrial cancer,” Dr. Keating said. “Women concerned about these cancers can be reassured that this protective effect appears to persist for decades after discontinuing use.”
Prior studies have indicated that oral contraceptives may be associated with an increased risk of breast cancer.
In terms of breast cancer risk, the study “again extends follow-up and shows that risk of breast cancer was higher for current and ever users through age 50,” although the lifetime risk was not elevated, Dr. Keating said.
“The counseling regarding the effect on breast cancer is more complex,” she said. “I tell women about the very small increased risk of breast cancer during and immediately after use. Because cancer is very rare among women at the ages when OCPs are typically prescribed, the absolute risk increase is extremely small. This paper adds reassurance that this small increase in risk does not persist.”
For certain patients, the association may be more relevant.
“For most women, this risk is so small that it should be a limited factor in their decision to start OCPs,” Dr. Keating said. “However, for women with a substantially higher risk of breast cancer, or a family history of breast cancer at a young age, the small increased risk of breast cancer during and immediately after OCP use is more relevant, and counseling should include carefully weighing the benefits and harms of OCPs with other forms of contraception (and no contraception).”
Dr. Samuel S. Badalian
Although the protective effects of oral contraceptives on ovarian and endometrial cancer were well known, the study describes long-term outcomes that can further inform patient counseling, said Samuel S. Badalian, MD, PhD, chief of the department of obstetrics and gynecology at Bassett Medical Center in Cooperstown, N.Y., and clinical professor of obstetrics and gynecology at the State University of New York, Syracuse.
“Women with individual or family risk factors of ovarian or endometrial cancers will need to know about the protective effects of oral contraceptives and long-term benefits related with their use (30-35 years after discontinuation),” Dr. Badalian said. “Women with family history of breast cancer need to know that lifetime risk of breast cancer might not differ between ever and never users, even if there is an increased short-term risk.”