-- Robert Preidt
WEDNESDAY, April 4 (HealthDay News) -- There appears to be a
link between an injectable form of progestin-only birth control,
best known as Depo-Provera, and an increased risk of breast cancer
in young women, new research suggests.
For the study, researchers compared more than 1,000 Seattle-area
women, aged 20 to 44, who were diagnosed with breast cancer, and
more than 900 women without breast cancer.
Recent use of the injectable contraceptive (formally called
depo-medroxyprogesterone acetate or DMPA) for a year or longer was
associated with a 2.2-fold increased risk of invasive breast
cancer, the study found.
This increased risk appeared to fade within months after women
stopped using the contraceptive, and women who used the
contraceptive for less than a year or who had stopped using it more
than a year earlier did not have any increased risk of breast
cancer, according to the findings published online and in the April
15 print issue of the journal
"Although breast cancer is rare among young women and the elevated risk of breast cancer associated with DMPA appears to dissipate after discontinuation of use, our findings emphasize the importance of identifying the potential risks associated with specific forms of contraceptives given the number of available alternatives," study leader Dr. Christopher Li, a breast cancer epidemiologist at the Fred Hutchinson Cancer Research Center in Seattle, and colleagues wrote.
"In the United States, many women have numerous options for contraception, and so it is important to balance their risks and benefits when making contraceptive choices," Li noted in a news release from the research center.
While the study uncovered an association between Depo-Provera
and raised breast cancer risk, it could not prove a
Commenting on the study, Dr. Elizabeth Poynor, a gynecologic
oncologist and pelvic surgeon at Lenox Hill Hospital in New York
City, said, "This study further confirms that some types of
progestins are not healthy for the breast. For women who are at
elevated risk to develop breast cancer based on family history, or
even age, this type of contraception may not be a good choice for
But another expert cautioned that the study did have its
Dr. Freya Schnabel, director of breast surgery at NYU Clinical
Cancer Center in New York City, noted that the women in the study
who seemed at highest risk of developing breast cancer while on
Depo-Provera were those with a family history of the disease or
women who had never had children (another known risk factor).
Furthermore, she said, "the study did not include information
about all breast cancer risk factors in the participants, and this
is a real limitation of the analysis which could impact on the
results. Also, the mechanism by which the progesterone would
increase risk only in current users is not clear."
According to Schnabel, all of this means that "more detailed
studies are needed to clarify the relationship between this
contraceptive method and risk of breast cancer."
The research was funded by the U.S. National Cancer Institute
and the Department of Defense Breast Cancer Research Program.
Planned Parenthood has more about the
birth control shot.
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