Contraceptives Dramatically Decrease Risk of Some Gynecological Cancers
May 1, 2023
EXECUTIVE SUMMARY
Contraceptives can reduce the risk of some gynecological cancers, including protection against ovarian cancer, endometrial cancer, and uterine cancer.
- Combined oral contraceptives can lower a person’s risk of ovarian cancer over several decades.
- The copper intrauterine device (IUD) also can decrease the risk of ovarian cancer.
- The levonorgestrel IUD can help prevent endometrial cancer.
Contraceptives provide protection against gynecological cancers, including probable protection against endometrial cancer, and colorectal cancer, says Robert A. Hatcher, MD, chairman of the Contraceptive Technology Update editorial board and professor emeritus in gynecology and obstetrics at Emory University in Atlanta.
Women who have used oral contraceptives have a lower risk of endometrial and ovarian cancers than women who have never used the product, with a risk reduction of at least 30%. Oral contraceptives also are associated with a 15% to 20% lower risk of colorectal cancer, according to the National Cancer Institute.1“In general, the longer the duration of use, the greater the protection,” Hatcher says.
Hatcher cites information on the protective effects of contraception on ovarian cancer described by Michael S. Policar, MD, MPH, and George F. Sawaya, MD, in Contraceptive Technology.2
“People who have had a term pregnancy before age 26 have a lower risk of ovarian cancer than those who have not, and risk goes down with each full-term pregnancy,” the authors noted. “Oral contraceptive use reduces the risk of ovarian cancer by as much as 80% in people age 40 to 59 years. Not only does longer duration of use provide more protection, but the effect lasts for as long as 15 years after oral contraceptives are discontinued.”
The Depo-Provera injection (DMPA) also provides protective effects. “The same effect is seen with DMPA; a case control study in Thailand showed a 83% risk reduction for epithelial ovarian cancer when the duration of DMPA use was longer than three years,” Policar and Sawaya noted.
Certain hormonal contraceptives are helpful because they prevent ovulation, which can decrease one’s risk of ovarian cancer, explains Stephanie Delkoski, DNP, APRN, WHNP-BC, a clinical assistant professor at the University of Minnesota School of Nursing.
Delkoski recalls a patient with a genetic risk of ovarian and breast cancer. “She was under care of the cancer prevention team, and they wanted her on a contraceptive method to prevent ovulation — a hormonal option,” she explains. “[The patient] opted for a NuvaRing because that can decrease a person’s risk of ovarian cancer.”
The etonogestrel/ethinyl estradiol NuvaRing is a combination hormonal contraceptive. The ring is inserted in the vagina for three weeks and then is taken out for one week, to allow withdrawal bleeding. Then, a new ring is inserted. It is inserted like a tampon and does not require specific positioning to be effective.3
Women who have used oral contraceptives are at a 30% to 50% lower risk of ovarian cancer than women who have never used oral contraceptives, according to research. The protective effect increases the longer a person uses the contraceptives. Benefits can continue for up to 30 years after stopping contraceptives.4-8
The levonorgestrel intrauterine device (IUD) can be used to prevent endometrial cancer. “I have seen that used in a postmenopausal patient with a history of abnormal uterine cells,” Delkoski explains. “In those patients, their endometrial hyperplasia is managed, and an IUD placed after [the abnormal cells are removed] is a maintenance regimen to prevent it from coming back.”
Patients with this history and risk factor for endometrial cancer can use a hormonal IUD for the rest of their lives. “Because it keeps the lining of the uterus really thin, the levonorgestrel IUD has benefits in endometrial cancer prevention,” Delkoski says. “The patient was post-menopausal, so the IUD was simply used for cancer prevention.”
The primary benefit of the copper IUD is its longevity and its ability to prevent pregnancy, says Mitchell Creinin, MD, a professor and director of the Complex Family Planning Fellowship at University of California, Davis Health. “It has tradeoffs and is not as effective as the 52 mg levonorgestrel IUD, but it lasts longer,” he adds.
The copper IUD is effective for at least 12 years, while the 52 mg levonorgestrel Mirena and Liletta IUDs are effective for eight years, according to recent research.1,3 Tradeoffs include increased bleeding and cramping for most users. In the first year of using the copper IUD, 10% to 15% of people do not tolerate it and discontinue use. But those who do continue find it acceptable, Creinin says.
The copper IUD also can decrease the risk of cervical, endometrial, and ovarian cancers, and it can be used as an effective emergency contraception.4,7,8 “Certain types of ovarian cancers are prevented by the copper IUD,” Creinin says.
Most women who choose the copper IUD as their contraceptive method do so because they want an effective contraceptive without hormones. Based on existing studies and evidence, reproductive health clinicians also could counsel patients on the noncontraceptive benefit of the device reducing the risk of ovarian cancer.
Hormonal IUDs also reduce the risk of ovarian cancer and endometrial cancer, Creinin notes. Research also suggests hormonal IUDs can protect against cervical cancer.4,5
“We know, based on how the IUD functions on the endometrium and from studies done in people who have early cancers, that it’s going to work physiologically,” Creinin explains. “Endometrial cancer is due to estrogen stimulation of the lining — overstimulation — which is why we see it more in obese women, for example. The hormonal IUD turns off the estrogen receptors in the uterus.”
It is a similar concept to the use of tamoxifen, a breast cancer drug, to block estrogen in the breast. “In the uterus, the levonorgestrel will turn off the receptor,” Creinin adds.
Hormonal contraceptives may have benefits for women with myomas, the most common (benign) tumor in women. “While there are no randomized trials that have studied the effects of DMPA on myomas, DMPA has been shown in open label trials to decrease the bleeding associated with myomas and improve hemoglobin levels,” researchers noted. “DMPA use may also shrink myomas; however, the evidence on this is conflicting. One case-control study showed that DMPA use was associated with a lower risk of recurrent myomas after myomectomy.”9
REFERENCES
- National Cancer Institute. Oral contraceptives and cancer risk. Reviewed Feb. 22, 2018.
- Policar MS, Sawaya GF. Screening women for cervical, ovarian, and breast cancer. Contraceptive Technology. 21st Edition. Ayer Company Publishers, Inc. 2018.
- Organon. Patient information: NuvaRing. 2023.
- Zieman M, Hatcher RA, Allen AZ, Haddad L. Managing Contraception 2021-2022. 16th Edition. Tiger, GA: Bridging the Gap Foundation.
- Hatcher RA, Nelson AL, Trussell J, et al. Contraceptive Technology. 21st Edition. Ayer Company Publishers, Inc. 2018.
- Havrilesky LJ, Moorman PG, Lowery WJ, et al. Oral contraceptive pills as primary prevention for ovarian cancer: A systematic review and meta-analysis. Obstet Gynecol 2013;122:139-147.
- Wentzensen N, Poole EM, Travert B, et al. Ovarian cancer risk factors by histologic subtype: An analysis from the Ovarian Cancer Cohort Consortium. J Clin Oncol 2016;34:2888-2898.
- Amat L, Bulach A, Leclercq M, et al. Additional non-contraceptive effects of contraception: CNGOF Contraception Guidelines. Gynecol Obstet Fertil Senol 2018;46:883-888.
- Wu W-J, Bartz D. Injectable contraceptives. Contraceptive Technology. 21st Edition. Ayer Company Publishers, Inc. 2018.
Contraceptives can reduce the risk of some gynecological cancers, including protection against ovarian cancer, endometrial cancer, and uterine cancer. Women who have used oral contraceptives have a lower risk of endometrial and ovarian cancers than women who have never used the product, with a risk reduction of at least 30%.
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