Recent use of oral contraceptives was shown to be associated with a higher risk for the development of breast cancer in a new study. The study considered more recent formulations of oral contraceptives and is therefore thought to be more valid for young women today.
The research study was carried out at the Fred Hutchinson Cancer Research Center in Seattle and the study was published in the journal Cancer Research. The experimental design was a nested case-control study and 1,102 women, ages 20 years to 49 years, who were diagnosed with invasive breast cancer were included. A total of 21,952 controls were matched to the cases according to age, year of being diagnosed with breast cancer, enrollment time in study and medical chart availability. Detailed data on oral contraceptive use was obtained from electronic pharmacy records.
Recent oral contraceptive use; that is, within the prior year, was associated with an increased risk of developing breast cancer relative to never or former oral contraceptive use. The risk for breast cancer was higher by about 50 percent for women who used oral contraceptives in the previous year compared to women who used oral contraceptives in the past or never. The results showed that the association was stronger for breast cancers that were estrogen receptor positive compared to estrogen receptor negative types of breast cancer. Elevated risk was noted for oral contraceptives that involved high-dose estrogen, ethynodiol diacetate or triphasic dosing with 0.75 mg of norethindrone, on average, compared with other types of oral contraceptives. There was no added risk for oral contraceptives that contained a low dose of estrogen.
The study authors are reported to have stated that larger studies with larger sample sizes should be carried out in the future to confirm and expand these results. Most women who take oral contraceptives take low-dose estrogen pills and it has been reported that only about one percent have a prescription for high-estrogen pills.
The results from the study are important for clinical decisions about prescribing oral contraceptives to younger women. It is also important that younger women are aware of these increased risks so they can make informed decisions. Whereas, there have been many reports on risk for the development of breast cancer and other health problems that may be associated with use of estrogen-based oral contraceptives, as well as estrogen replacement therapy at menopause, it can be very confusing for women to make choices for themselves. Conflicting reports and changing suggestions have caused confusion that is hard to sort out.
While every woman needs to make her own choices based on her family history and self-assessment of her state of health, this study has provided another piece of useful information that can be considered regarding use of oral contraceptives.
In the past, some physicians that prescribe oral contraceptives have advised women to only take the oral contraceptives for about a year and then take some time off from the estrogen-based pills. During the time out, women are advised to use another form of contraception. This is an option that may alleviate some of the risk for the development of breast cancer, although studies are needed to confirm this.
By Margaret Lutze