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Teens births declining but geographic ‘hotspots’ defy trend

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Do Women Really Need to Wait That Long?

Reassuring news on depression and OC use

PMDD: Genetic clues may lead to improved treatment

Breast cancer risk when there is a family history

Body weight link to breast and endometrial cancers (and 11 others)

Family Planning in 2017 and Beyond

Make Me Cry: Depression Link (Again)?

Managing implant users’ bleeding and spotting

Zika: Updated guidance for providers

Pharmacist-prescribed contraceptives

Hot off the press! 2016 MEC and SPR

Zika virus fears prompt increased request for abortion in nations outlawing abortions

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Good news on the family planning home front!

War Against Planned Parenthood Hurts Women

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Center of the Storm

Ambivalence

Menopause, mood, mental acuity, and hormone therapy

Emergency contraception for teens

Postpartum Contraception: Now, Not Later

Reproductive tract infections, sexually transmitted infections, or sexually transmitted diseases: “a rose by any other name…”

Are we practicing what we preach?

Be alert to VTE in hormonal contraceptive users

LARC among teens increased 15-fold, but not enough

Brain cancer and hormonal contraception

Free tools: Easy access to the US Medical Eligibility Criteria for Contraceptive Use

Alcohol consumption when pregnancy is unwanted or unintended

Latest Data on Contraceptive Use in the United States

LateBreaker sampler from Contraceptive Technology conference

Emergency Contraceptive Pill Efficacy and BMI/Body Weight

Handout on Unintended Pregnancy and Contraceptive Choice

Ask About Withdrawal (Really!)

Rules to Practice By: Safety First and Cleanliness is Close to. . .

What’s Vanity Fair Got Against the NuvaRing?

Promising New Treatment for Hepatitis C

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The Recession’s Effect on Unintended Pregnancies

Lessons Learned from the Contraceptive CHOICE Project: The Hull LARC Initiative

Applying the “New” Cervical Cytology Guidelines in Your Practice

Acute Excessive Uterine Bleeding: New Management Strategies

Medical indications for IUD use in teens

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Update on Emergency Contraception

Contraceptivetechnology.com New and Improved

Brain cancer and hormonal contraception
April 2015

 

A recent Danish study reported that ever use of hormonal contraception was associated with a 50 percent increased risk of glioblastoma multiforme, a deadly form of cancer responsible for 80% of brain tumors.[1] Longer term use, ask at least 5 years, was associated with a 90 percent increased risk, compared to women who did not use hormonal contraceptives. The results received substantial media coverage, with a Time magazine headline stating “Birth control pill risks may now include brain cancer”[2] and CBS news broadcasting a similar banner.[3]

The case-control study drew from national Danish health and administrative registries on cancer and on pharmaceutical use. The researchers identified 317 women with glioma and matched them to 2,126 controls.

The greatest association occurred with progestin-only contraceptives, with an odds ratio of 2.5. For those women for whom progestin-only contraceptives were their solo method, the odds ratio was 4.1. These increased odds ratios may at first glance appear concerning, however, several factors place the study results in more balanced perspective.

First, glioma is rare, with only 0.17% incidence, or about a tenth the incidence of breast cancer. Even if there were a true doubling or quadrupling of risk, its incidence would still be rare.

Second, a meta-analysis 11 earlier case-control studies analyzing 4,860 cases failed to find a correlation, or found a trend toward the inverse, that the glioma risk decreased with use of hormonal contraceptives or hormone therapy.[4]

Third, although the cases were matched to controls in regard to age, schooling, parity, history of allergy or asthma, and use of hormone therapy, antidepressants, antihistamines, anti-asthma medications, and non-aspirin NSAIDS, the only established risk factors for glioma are radiation and rare genetic disorders.[5]

Fourth, case control studies are especially vulnerable to bias because so few confounding factors can be controlled. Generally, odd ratios of 4 or below might be regarded as “non-informative.”[6]

Fifth, the number of cases in some of the data cells was very low. For example, only 3 cases involved solo use of progestin-only contraceptives.

Sixth, the p value for the odd ratio of solo use of progestin-only methods was 1.0, so it did not achieve 0.05 value expected for 95 percent confidence. The p values for other findings also did not meet the standard for 95 percent level of confidence.

Bottom-line? This study does not provide compelling evidence of risk.

 

—Deborah Kowal, MA, PA, President, Contraceptive Communications, Inc.

 


[1] Anderson L, Friis S, Hallas J, et al. Hormonal contraceptive use and risk of glioma among younger women: a nationwide case-control study.  Br J Clin Pharmacol 2014 Oct 26. doi: 10.1111/bcp.12535. [Epub ahead of print]

[2] Park A. Birth control pill risks may now include brain cancer. Time 2015, Jan. 22.

[3] Mozes A. birth control pill may be linked to rare brain tumors. CBS News 2015; Jan 22, 2:25 pm.

[4] Qi Z, Shao C, Zhang X, et al. Exogenous and endogenous hormones in relation to glioma in women: a meta-analysis of 11 case-control studies. PLOS One 2013;8:1-11. doi:10.1371/journal.pone.0068695

[5] Wigertz A, Lonn S, Mathiesen T, et al. Risk of brain tumors associated with exposure to exogenous female sex hormones. Am J Epidem 2006;164:629-36.

[6] Grimes D, Schulz K. False alarms and pseudo-epidemics: the limitations of observational epidemiology. Obstet Gynecol 2012;120:920-7.