CONTENTS
Chapters
- Research and Regulatory Approval
- Use of Injectables
- Effectiveness and Reversibility
- Side Effects and Complications
- More Evidence in the Cancer Debate
- Noncontraceptive Health Benefits
- Counseling Issues
- Communicating with the Public
- Maximizing Access and Quality
Published with this issue:
HIGHLIGHTS
Published by the Population Information Program, Center for Communication
Programs, The Johns Hopkins School of Public Health, 111 Market Place, Suite 310, Baltimore, Maryland
21202-4012, USA
Volume XXIII, Number 2
August 1995 |
DMPA Research
Tests of DMPA in beagle dogs and monkeys in the early 1970s
raised questions about cancer that delayed US regulatory approval
and held back use in many countries. Beagles developed breast
tumors and some monkeys developed endometrial tumors in tests
then required by the US FDA of any new hormonal contraceptive
(148). These studies were influential because at the time there
was little information on the long-term effects of DMPA use among
women (322). Many experts questioned the relevance to humans of
the beagle and monkey studies, however (3, 10, 136, 313, 330,
346).
The WHO Collaborative Study of Neoplasia and Steroid
Contraceptives examined the risk of cancer among users of
hormonal contraceptives and reached the following conclusions,
published largely in 1991, about DMPA and cancer:
- Breast cancer: No increased risk overall, but the
study found that DMPA users had an increased risk for several years
after starting DMPA—perhaps due to accelerated growth of existing tumors.
Some of the apparent increase in risk may be explained by detection
bias (see Chapter 5.1).
- Cervical cancer: No increased risk of invasive cancer
(see Chapter 5.2).
- Endometrial cancer: Protective effect (see Chapter
5.3).
- Ovarian cancer: No increased risk (see Chapter
5.4).
- Liver cancer: No increased risk (see Chapter
5.5).
The findings about breast and endometrial cancer were the
most crucial because they answered the long-standing questions
raised by animal studies.
The WHO study provided epidemiologic evidence that humans
differ from these animals in their response to hormones. The US
FDA no longer requires testing contraceptive hormones for
carcinogenicity in beagles (148).
The WHO study led the US FDA to change its position in 1992
and approve DMPA. US FDA approval removed a source of controversy
in the history of DMPA: use in developing countries of a drug
that was not approved for contraceptive use in the US.
The US had been one of the few countries to withhold approval of DMPA.
Over 90 countries had approved DMPA before the US (see Figure
1). Following US approval, India, the
Philippines, and several other countries also approved DMPA. By comparison,
NET EN is registered in over 60 countries. Registration does not necessarily
mean, however, that a product is readily available.
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