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Quelle: Presse-Information Fachblatt The Lancet

Pille schützt viele Jahrzehnte lang vor Eierstockkrebs

Die Einnahme der Antibabypille kann jährlich zehntausende von Leben retten. Frauen die in der Vergangenheit die Pille verordnet bekamen, haben ein deutlich geringeres Risiko an Eierstockkrebs zu erkranken.  Wissenschaftler fordern daher "Weg mit der Rezeptpflicht!", da diese unnötigerweise den Zugang zu einem wichtigen Anti-Krebsmittel  erschwert.

 

Im renommierten Fachblatt The Lancet wurde kürzlich ein Artikel publiziert (siehe unten), der aufgrund seiner beeindruckenden Daten die Frage endgültig beantwortet, ob die Mehrzahl der Frauen ein orales Kontrazeptivum - gemeinhin als "Antibabypille" bekannt - einnehmen sollten oder lieber nicht.
Valerie Beral und ihre Kolleginnen und Kollegen analysierten 45 epidemiologische Studien, die in den vergangenen Jahren den Zusammenhang zwischen der Einnahme der Pille und dem Auftreten des in den meisten Fällen tödlich verlaufenden Eierstock-Krebses (Ovarial Karzinom) untersuchten. An den Studien nahmen 7.308 Frauen mit  und 32.717 Patienten ohne Eierstockkrebs teil, die alle irgendwann in ihrem Leben die Antibabypille eingenommen hatten.

Diese sog. Metaanalyse aller vorhandenen Untersuchungen zeigt ohne jeden Zweifel, dass die Einnahme einer beliebigen Antibabypille auch noch viele Jahre später in der Lage ist,  das Risiko an Eierstockkrebs zu erkranken deutlich vermindert.
Diese  positive Wirkung der Pille beginnt sehr schnell und nimmt bei einer Langzeiteinnahme weiter zu. Die Autoren kamen zu dem Schluss dass die oralen Kontrazeptiva in den vergangenen 50 Jahren weltweit mindestens 200.000 Fälle von Eierstockkrebs und 100.000 entsprechende Todesfälle verhindert haben.

Doch die Erfolgsstory der Pille wird täglich neu geschrieben. Alle zusammengetragenen  wissenschaftlichen Daten sprechen nach Meinung der Experten dafür, dass   durch die Einnahme der Pille in Zukunft pro Jahr  mindestens 30.000 Fälle von Eierstockkrebs verhindert werden. Diese Funde - so die Autoren der Studie - setzen einen völlig neuen Standard für die Möglichkeit einen tödlichen Krebs durch Vorsorgemaßnahmen zu verhindern.

Eierstockkrebs ist in den USA die häufigste Ursache für den Tod aufgrund eines gynäkologischen Tumors. Da es keine praktikablen Früherkennungsmaßnahmen gibt, wird der Eierstockkrebs meist in einem späten Stadium entdeckt und kann dann nicht mehr geheilt werden.

In einem die Untersuchung begleitenden Editorial wird mit Nachdruck die Forderung aufgestellt, die Rezeptpflicht für die Pille abzuschaffen, da diese eine unnötige Barriere darstellt, die viele Frauen davon abhält, sich die Pille zu beschaffen.

Selbstverständlich trifft es auch nach der Veröffentlichung dieser Studie weiter zu, dass die Langzeiteinnahme der Pille bei einzelnen Frauen auch negative Auswirkungen haben kann. Umstritten ist bisher beispielsweise, ob die Pille das Risiko für Brust- und Gebärmutterhalskrebs möglicherweise leicht erhöht. Und selbstverständlich sollten auch in Zukunft jene Frauen die Pille nicht über einen längeren Zeitraum einnehmen, bei denen die auf Risikofaktoren basierenden bekannten Kontraindikationen vorliegen - wie beispielsweise Lebererkrankungen, oder eine familiäre Häufung von Thrombosen.

Bilanziert man aber die bewiesenen Vor- und denkbaren Nachteile der Langzeiteinnahme der Antibabypille, so überwiegt  aus wissenschaftlicher Sicht der Nutzen den denkbaren Schaden bei weitem.

 


 

 

Den Volltext des Artikels als PDF-Datei finden Sie hier hier

 

 

Lancet 2008; 371: 303–14

The case for preventing ovarian cancer


In today’s Lancet, Valerie Beral and colleagues provide a definitive analysis of the association between oralcontraceptives and ovarian cancer. Although thefindings are not unexpected, this study is impressiveand compelling. It pools worldwide data from 45 epidemiological studies and shows beyond doubt that ovarian cancers can be prevented by the long-termuse of different generations of oral contraceptives.


Moreover, this substantial protection begins quickly, and increases with increasing duration of use.In population terms, the findings are dramatic.


The authors suggest that during the past 50 years,200 000 cases of ovarian cancer and 100 000 deathsfrom the disease have already been prevented worldwidethrough the use of oral contraceptives.

They calculate that at the current level of contraceptive use, at
least 30 000 cases of ovarian cancer could eventually be
prevented every year
. These findings set a new standard
in primary prevention for a deadly cancer and haveimportant public-health implications.


Ovarian cancer is an aggressive and fatal disease. Inthe USA, ovarian cancer is the most common cause ofdeath from a gynaecological malignancy. Older womenare at highest risk; around two-thirds of affected womenare 55 years or older. The absence of proven screeningmethods and specific symptoms means that ovariancancer is often diagnosed late.

Despite advances in treatment, long-term survival rates remain poor—thus primary prevention would be a major advance.This latest study raises the question again of whetheroral contraceptives should be made more widelyavailable to women to protect them from ovariancancer. We believe that the case is now convincing.


Women deserve the choice to obtain oral contraceptives
over-the-counter
, removing a huge and unnecessarybarrier to a potentially powerful cancer-preventingagent. Since the introduction of oral contraceptivesin the 1960s, there have been many debates abouttheir health benefits and safety. In the current eraof the combination pill with low-dose oestrogenformulations, the adverse cardiovascular effects areshort term and have diminshed over time. The effectof oral contraceptives on cancer risk is more complex.
Whilst being shown to decrease the risk of ovarian and endometrial cancers, oral contraceptives may increase the risk of breast and cervical cancers. However, the best evidence on the net effect of oral contraceptives shows a reduction in risk of cancers. Given the well established benefits of avoiding pregnancy, which has a high morbidity and some mortality, even in developed countries, the risk-benefit equation is weighted strongly in favour of giving oral contraceptives to women who seek them, and who are not contraindicated from taking them.

Oral contraceptives have become the keystone of reproductive health by virtue of their ability to prevent pregnancy. But whether women in their 20s will be prepared to take an oral contraceptive
to prevent ovarian cancer where the life-time risk is low (1 in 70) remains open to uncertainty. While the average 20-year-old woman may not be thinking about whether she will get ovarian cancer (she is more likely to be concerned about breast and cervicalcancer, where the lifetime risk is much higher), a strong message about the overall cancer preventing benefits of oral contraceptives would be a positive public-health message, empowering women to decide
for themselves about the evidence. Women contend with much adverse publicity about the risks of oral contraceptives, which surely influences their decision about whether to take these agents. Very little is said in the press about the health benefits.

Today’s paper in The Lancet helps to redress that balance.There are few drugs available that confer powerful and long-lasting protection against a highly lethal malignancy after such a short exposure. In translating the evidence from this large systematic review to individual women, oral contraceptives should now be made more widely available. Contraindications include a history of thromboembolism, heart disease, migraine,liver disease, and several other relatively uncommon conditions. The benefits of oral contraceptives in primary ovarian cancer are independent of the preparation,and vary little by ethnic origin, parity, family history of
breast cancer, body-mass index, and use of hormone replacement therapy.

We strongly endorse more widespread over-the counter access to a preventive agent that can not only prevent cancers but also demonstrably save the lives of tens of thousands of women.

 



For more on the net effect of
oral contraceptives see
BMJ 2007; 335: 651
 

For more on health benefits and
safety of oral contraceptives
see Am J Obs Gynae

 

 

Correspondence to:

Secretariat, Cancer Research UK

Epidemiology Unit, Richard Doll

Building, Roosevelt Drive, Oxford

OX3 7LF, UK

collaborations@ceu.ox.ac.uk

 

 

 

Ovarian cancer and oral contraceptives



Since the 1960s, oral contraceptives have become a dominant form of female contraception in most developed countries. In the UK, 25% of women aged 16–49 years and 62% of women aged 16–24 years rely on combined oestrogen–progestin or progestin-only
(minipill) oral contraceptives.1

In the USA, 19% of women aged 15–44 years (and 32% of 20–24-year-olds) take oral contraceptives. 2 These drugs are the most effective reversible birth-control method, and widespread use has been the cornerstone of family-planning initiatives worldwide. A causal role for oral contraceptives invarious cancers was first suspected soon after their use became widespread, but today’s low-dose formulation are relatively safe drugs. Oral contraceptives have been linked with increased risks for some cancers (breast andcervix) and with protective effects for others (ovarian, endometrial, and colorectal).3

Calculation of the net effecton women’s health is fraught with uncertainties. There are inherent difficulties associated with ascertaining the nature of exposure to oral contraceptives, such as age at first use, duration of use, time since last use, formulation of contraceptives (sequential, combined, orprogestin-only), and dose. Furthermore, epidemiological studies must include information about potential confounders, such as sociodemographics, family history of cancer, comorbidity, reproductive-health variables, history of hormone-replacement therapy (HRT), and   relevant lifestyle characteristics. For a woman in her 50s or 60s, recalling past use of oral contraceptives is not easy.

In case-control studies, recall bias may further compoundthis problem because women with cancer might make a greater effort to recollect past exposures than their cancer-free counterparts.Recall bias might be the most relevant confounderin the recent studies in populations with substantial media exposure to the knowledge that drugs such as oral contraceptives can have harmful effects.

Prospective cohort studies are mostly free of recall biases because
exposure information is collected before the onset of the cancer outcome. However, prospective cohorts are more expensive and tend to have lower statistical power than case–control studies. Except for cervical cancer, for which increases in risk are more than moderate,4 directions of changes in risks associted with ever having used oral contraceptives are variable and modest, in the range of 10–50%, for ovarian, endometrial, breast, and colorectal cancers.3    Precise and accurate measurementof modest relative risks and disentangling them from spurious confounders require very large studies. Individually,each study has little or no hope of furthering our understanding of how risk varies by histological subtype, menopausal status, or other relevant variables for which the assessment of stratum-specific associations would provide useful insights into causation.


For these reasons and more, the study by the Collaborative Group on Epidemiological Studies of Ovarian Cancer5 in today’s Lancet makes a major contribution to our understanding of the role of oral
contraceptives in the causation or prevention of ovarian cancer.

 The researchers took advantage of the great statistical precision afforded by the combination of 45 studies, many of which were prospective cohorts. The Collaborative Group tackled many questions about the quantitative effects of oral contraceptive use, age at start, duration of use, time since cessation, and era of use, all infinely stratified analyses that accounted for key a-priori
confounders and design variables. The Group calculates that use of oral contraceptives will eventually prevent 30 000 ovarian cancers per year. The notion that this unequivocal protective effect stems from the cumulative suppression of ovulatory cycles was strongly supported by the homogeneity of results across eras of use (as
a proxy for oestrogen dose) and in the long-lasting protective effect after cessation of use.  Reassuringly, case–control studies reproduced, on average, the same magnitude of protective effect found in cohort studies, which assuages concerns about recall bias.
The Collaborative Group’s new analysis provides useful insights into the association with ovarian-cancer histology. The protective effect was largely the same for epithelial and non-epithelial tumours, although there was less evidence that oral contraceptive use prevents mucinous ovarian cancer, which accounts for fewer than 15% of all incident cases .

Oral contraceptives are not the only exogenous source hormones that might influence ovarian cancer risk in women. The Million-Women Study by the same group6  found that the mucinous ovarian cancer differed from other types after HRT. Use of HRT was associated with increased risk of serous and mixed histology

 

 

 

 

 

 

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