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Vorbeugung
Gebärmutterhalskrebs (Cervixkarzinom-Prophylaxe):
Die umstrittene Impfung gegen die HP-Viren
Typ 16 und 18 ist offenbar doch effektiver
als es die Kritiker wahrhaben wollen. Sie
führt bei breiter Anwendung bei der für die
Impfung in Frage kommenden Zielgruppe zu einem
nahezu 100%igen Schutz vor Gebärmutterhalskrebs.
Das
Zervixkarzinom (lateinisch Carcinoma cervicis
uteri), auch Kollumkarzinom (von lateinisch
Collum für „Hals“) oder Gebärmutterhalskrebs
genannt, ist ein bösartiger (maligner) Tumor
des Gebärmutterhalses. Es ist weltweit der
zweithäufigste bösartige Tumor bei Frauen.
Die häufigste Ursache für ein Zervixkarzinom
ist eine Infektion mit
humanen Papillomviren
(HPV).
Derzeit
sind zwei Impfungen in Deutschland auf dem
Markt, die sich gegen die Typen 16 und 18
des HPV richten, die für die Entstehung von
70% der Erkrankungen verantwortlich sind. Zielgruppe
der Impfungen sind junge Mädchen und junge
Frauen in der Altersgruppe von 11-26 Jahren
die sexuell noch nicht aktiv sind. Diese Impfungen
sind allerdings umstritten. Kritiker werfen
den Herstellern der Impfstoffe vor, dass sie
die Wirkung der Impfung aus wirtschaftlichen
Gründen zu positiv darstellen und raten aufgrund
der angeblich mangelhaften Effizienz der Immunisierung
eher von der Impfung ab.
Jetzt
zeigen die Ergebnisse der im renommierten
Fachblatt
The Lancet
veröffentlichten PATRICIA-Studie
aber, dass die Impfung offenbar doch sehr
effektiv vor der Infektion mit den HPV-Typen
16 und 18 schützt. Außerdem kommt noch ein
deutlicher Schutz gegen andere krebserregende
HPV-Typen hinzu, die die verbleibenden 30%
der Krebsfälle am Gebärmutterhals verursachen.
Dadurch erhöht sich die allgemeine Schutzwirkung
gegen die Entwicklung von Cervixkarzinomen
um weitere 11-16%.
Die Forscher betonten, dass die Impfung bei
breiter Anwendung in einigen Dekaden das Vorkommen
von Gebärmutterkrebs deutlich vermindern wird.
Doch um die für die Erkrankung verantwortlichen
Viren ganz auszurotten ist die Zielgruppe
der Impfungen einfach zu klein. Dies
wäre nur möglich, wenn sich auch die andere
Hälfte der sexuell aktiven Menschen - Jungen
und Männer - gegen HPV impfen ließen. In diesem
Fall könnten die krebserregenden Viren relativ
schnell bei beiden Geschlechtern ausgerottet
werden.
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zum
Jahresindex 2009

THE LANCET: Press Release
(PATRICIA trial): FINAL ANALYSIS
SHOWS
HPV VACCINE HIGHLY EFFECTIVE AT PREVENTING PRECANCEROUS
CERVICAL LESIONS, AND HAS SUBSTANTIAL PROTECTIVE
EFFECT IN POPULATIONS RELEVANT TO VACCINATION PROGRAMMES
The
final analysis of the PATRICIA study shows
that the
HPV-16/18 AS04-adjuvanted vaccine (GlaxoSmithKline)
has high efficacy against the precancerous cervical
lesions that can eventually lead to cervical cancer.
The vaccine also shows cross-protective efficacy
against other oncogenic (cancer-causing) HPV types
closely related to HPV-16/18. Furthermore, it also
shows efficacy in the cohorts relevant to universal
mass vaccination and catch-up programmes. The findings
are reported in an
Article
Online
First and in
an upcoming edition of The Lancet, written by Dr
Jorma Paavonen, University of Helsinki, Finland,
and colleagues.
The
study looked at women aged 15-25 years who
were vaccinated at months 0, 1, and 6. Analyses
were done in the according-to-protocol cohort for
efficacy (ATP-E, which included all women who were
given 3 vaccine doses,
had normal pap smears or pap
smears showing mild abnormalities
at baseline, complied with
the protocol and were evaluable for the primary
endpoint; vaccine=8093, control=8069), the total
vaccinated cohort (TVC, included all women who received
at least one vaccine dose, regardless of their baseline
HPV status; represents young sexually active population;
vaccine=9319, control=9325), and TVC-naïve (no evidence
of oncogenic HPV infection at baseline; represents
women before sexual debut, vaccine=5822, control=5819).
The primary endpoint was
to assess vaccine against cervical intraepithelial
neoplasia 2+ (CIN2+)—the precancerous lesions
that can eventually lead to full-blown cervical
cancer.
The
mean follow-up was just under
three years
after the third dose. Vaccine efficacy against
CIN2+ that was associated with HPV-16/18 was 93%
in the primary analysis and 98% in an analysis in
which causality to HPV type was assigned in lesions
infected with multiple oncogenic types. Vaccine
efficacy against CIN2+ irrespective of HPV type
detected in lesions was 30% in the TVC and 70% in
the TVC-naïve. Corresponding values against CIN3+
(more serious precancer) were 33% in TVC and 87%
in TVC-naïve, indicating the larger contribution
of HPV-16/18 to The vaccine was also shown to be
protective against other oncogenic (cancer causing)
HPV types – most notably HPV-31 (related to
HPV-16) and HPV-45 (related to HPV-18).
Overall, the vaccine efficacy was calculated as
between 37% and 54% against 12 non-vaccine oncogenic
HPV types.
Globally, around 70% of cervical cancer is estimated
to be caused by HPV-16/18, with the remaining 30%
caused by other oncogenic HPV types. Thus the cross-protective
efficacy of this vaccine could represent 11—16%*
additional protection against cervical cancer to
that afforded by efficacy against HPV-16/18.
The
authors say: “The reduction in the number
of lesions in the TVC and TVC-naïve
was accompanied
by a significant proportional reduction in the numbers
of colposcopy referrals and cervical excision procedures.
Reduction in the number of cervical excision procedures
might be accompanied by a reduction in the numbers
of preterm births and other adverse pregnancy
outcomes because these outcomes have been shown
to be associated with the treatment of CIN.”
The
authors note the strengths and weaknesses of the
study. The strengths include its duration and size,
plus the diversity of the participants, which included
a broadly representative group of women from North
America, Latin America, Europe, and Asia-Pacific
regions. However Africa and some other regions were
not included, but trials have since begun in these
areas.
Limitations include that the true incidence rate
for CIN2+ lesions from non-vaccine HPV types could
have been underestimated, since it takes longer
for such lesions to develop compared to lesions
caused by HPV-16/18.
The
authors conclude: “The HPV-16/18 AS04-adjvanted
vaccine showed high efficacy against CIN2+ that
was associated with HPV-16/18 and non-vaccine oncogenic
HPV types, and substantial overall effect in cohorts
that are relevant to universal mass vaccination
and catch-up programmes.
“Although
the importance of continued tests for pap or HPV
in vaccinated and unvaccinated women must be emphasised,
HPV vaccination has the potential to substantially
reduce the incidence of cervical cancer and precancer,
and the numbers of colposcopy referrals and cervical
excision procedures.”
In
an accompanying
Comment,
Dr Karin B.
Michels, Harvard Medical School, Boston, USA
and Dr Harald zur Hausen,
German Cancer Research Centre,
Heidelberg, Germany,
say: “Currently, the targets for HPV vaccination
are girls and young women aged 11-26 years prior
to sexual debut. While good utilization
of the program will reduce cervical cancer incidence
in a couple of decades, this subgroup of the population
at risk is too small to limit the spread of the
virus.
The only
efficient way to stop the virus is to also vaccinate
the other half of the sexually active population:
boys and men.”
They
conclude: “Women have shouldered responsibility
for contraception since its inception. The
goal to eradicate sexually transmitted carcinogenic
viruses can be jointly carried by women and men
and could be accomplished within a few decades.”
Dr Jorma Paavonen, University
of Helsinki, Finland E)
Jorma.Paavonen@hus.fi
Dr
Karin B. Michels, Harvard Medical School, Boston,
USA (currently in Europe) E)
kmichels@rics.bwh.harvard.edu
For full
Article and
Comment,
see:
http://press.thelancet.com/patriciafinal.pdf
Notes to editors:
*the figure of 11—16% is found
by calculating 37—54% of the 30% (30% of cervical
cancers are from types of HPV other than 16 and
18)
Tony Kirby
Press Officer
The Lancet
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