Recent use of some birth control pills may increase breast cancer risk

August 1, 2014, American Association for Cancer Research

Women who recently used birth control pills containing high-dose estrogen and a few other formulations had an increased risk for breast cancer, whereas women using some other formulations did not, according to data published in Cancer Research, a journal of the American Association for Cancer Research.

"Our results suggest that use of contemporary oral contraceptives [] in the past year is associated with an increased risk relative to never or former oral contraceptive use, and that this risk may vary by oral contraceptive formulation," said Elisabeth F. Beaber, PhD, MPH, a staff scientist in the Public Health Sciences Division of Fred Hutchinson Cancer Research Center in Seattle, Washington.

"Our results require confirmation and should be interpreted cautiously," added Beaber. "Breast cancer is rare among young women and there are numerous established health benefits associated with oral contraceptive use that must be considered. In addition, prior studies suggest that the increased risk associated with recent oral contraceptive use declines after stopping oral contraceptives."

In a nested case-control study of 1,102 women diagnosed with breast cancer and 21,952 controls, Beaber and colleagues found that recent oral contraceptive use increased by 50 percent, compared with never or former use. All study participants were at Group Health Cooperative in the Seattle-Puget Sound area. Patients received a cancer diagnosis between 1990 and 2009.

Birth control pills containing high-dose estrogen increased breast cancer risk 2.7-fold, and those containing moderate-dose estrogen increased the risk 1.6-fold. Pills containing ethynodiol diacetate increased the risk 2.6-fold, and triphasic combination pills containing an average of 0.75 milligrams of norethindrone increased the risk 3.1-fold.

Birth control pills containing low-dose estrogen did not increase breast .

About 24 percent, 78 percent, and less than 1 percent of study controls who were recent oral contraceptive users filled at least one prescription in the past year for low-, moderate-, and/or high-estrogen dose , respectively, according to Beaber.

Unlike most previous studies that depended on women's self-report or recall, which may cause bias, Beaber and colleagues used electronic pharmacy records to gather detailed information on oral contraceptive use including drug name, dosage, and duration of medication.

Explore further: Strategies identified to improve oral contraceptive success with obese women

Related Stories

Strategies identified to improve oral contraceptive success with obese women

July 28, 2014
The findings of a new study suggest two ways to effectively address the problem that birth control pills may not work as well in obese women, compared to women of a normal body mass index.

Study shows breastfeeding reduced risk for ER/PR-negative breast cancer

October 18, 2012
Breast-feeding reduces the risk for estrogen receptor-negative and progesterone receptor-negative breast cancer, according to a study conducted at Columbia University's Mailman School of Public Health. Researchers examined ...

Risk of blood clots two-fold for women with polycystic ovary syndrome on combined pill

December 3, 2012
Women with polycystic ovary syndrome (PCOS) who are taking combined oral contraceptives have a 2-fold risk of blood clots compared with women without the disorder who take contraceptives, states a study published in CMAJ ...

Smoking linked with increased risk of most common type of breast cancer

February 10, 2014
Young women who smoke and have been smoking a pack a day for a decade or more have a significantly increased risk of developing the most common type of breast cancer. That is the finding of an analysis published early online ...

Study reveals contraceptive cancer risks

March 7, 2012
A study has revealed that injectable contraceptives that are widely used around the world influence the risk of developing several types of cancer.

Recommended for you

Research team discovers drug compound that stops cancer cells from spreading

June 22, 2018
Fighting cancer means killing cancer cells. However, oncologists know that it's also important to halt the movement of cancer cells before they spread throughout the body. New research, published today in the journal Nature ...

Dying cancer cells make remaining glioblastoma cells more aggressive and therapy-resistant

June 21, 2018
A surprising form of cell-to-cell communication in glioblastoma promotes global changes in recipient cells, including aggressiveness, motility, and resistance to radiation or chemotherapy.

Existing treatment could be used for common 'untreatable' form of lung cancer

June 21, 2018
A cancer treatment already approved for use in certain types of cancer has been found to block cell growth in a common form of lung cancer for which there is currently no specific treatment available.

Novel therapy makes oxidative stress deadly to cancer

June 21, 2018
Oxidative stress can help tumors thrive, but one way novel cancer treatments work is by pushing levels to the point where it instead helps them die, scientists report.

Higher body fat linked to lower breast cancer risk in younger women

June 21, 2018
While obesity has been shown to increase breast cancer risk in postmenopausal women, a large-scale study co-led by a University of North Carolina Lineberger Comprehensive Cancer Center researcher found the opposite is true ...

Researchers uncover new target to stop cancer growth

June 21, 2018
Researchers at the University of Wisconsin-Madison have discovered that a protein called Munc13-4 helps cancer cells secrete large numbers of exosomes—tiny, membrane-bound packages containing proteins and RNAs that stimulate ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.