Dear Dr.
Phillips,
Thank you for your reply!
The key
fact which most (maybe all!) news stories have omitted is that the
press release about the study discusses only the prevalence
of the four HPV types targeted by the vaccine (which they called
"vaccine-type HPV"), only two of which are "high-risk" strains
(types 16 & 18).
The Markowitz paper is much better than
the CDC's misleading press release about it.
Look a this graph (Markowitz's figure 1). You can see that, even
before the vaccine reduced the incidence of types 16 & 18,
most of the high-risk HPV infections were of other types,
confirming Winer, 2006.
From that graph, it appears that only about 19% of
high-risk HPV infections were types 16 & 18 in 2003–2006,
and only about 13% in 2007–2010.
It is frequently claimed (by Merck & by various authors,
including Markowitz)
that approximately 70% of cervical cancer cases are caused by types
16 & 18. That suggests that a 50% reduction in 70% of cases
would lead to an overall (0.5 x 0.7 = 0.35) = 35% reduction in
cervical cancer cases. But that is almost certainly a false hope.
It is based on very dubious assumptions:
- The
study from which the 70% number comes (de
Sanjose, et al, 2010) simply looked for the presence or
absence of various HPV strains in preserved tissue samples from
cervical cancer patients. They found that 71% of those patients
were infected with HPV type 16 and/or 18.
But that does not mean types 16 & 18 caused all those
cancers! For one thing, many of those patients were also infected
with other high-risk types of HPV, which presumably caused at
least some of the cancers. Also, 15% of the cancer patients had
no detectable HPV infection at all, which suggests that in a
significant percentage of the patients with HPV infections the
cancers might also have had other causes.
So it is statistically incorrect to conclude from
de Sanjose et al that 70% of cervical cancer cases are
caused by HPV types 16 & 18.
- There is evidence that HPV types
16, 18 & 45 may have higher oncogenicity than some other
high-risk types, because in women infected with those HPV strains
cervical cancer seems to develop at a somewhat younger age. A
higher oncogenicity would contribute to the high percentage of
current cervical cancer patients infected by those strains of
HPV.
But it almost certainly is not the only reason. The changing
relative prevalences of different HPV types may be a more
important cause.
Cervical cancer is typically diagnosed decades after the
infection. So the prevalence of various high-risk HPV types
decades ago is what largely determines the percentages of
today's cancer cases caused by those types. The
(different) prevalence of high-risk HPV types today is what will
determine the percentages of different types that cause cervical
cancer in the future. If types 16 & 18 were relatively more
prevalent compared to other high risk types thirty years ago than
they are today, then, like mediocre generals, we're building
defenses for the previous war, instead of the
next.
But the
news gets worse. Look at Markowitz's table 3:
Look at
the lines labeled "Vaccinated" and compare them with the lines
labeled "Unvaccinated."
Do you see
it? It is the vaccinated patients who have the
highest HPV infection rates!
The overall prevalence of HPV among
vaccinated sexually-active teens is 50.0%, but among unvaccinated
sexually-active teens it is only 38.6%.
The prevalence of high-risk HPV
strains other than 16 & 18 is similarly skewed: 35.2% of
vaccinated sexually-active teens are infected, and only 25.3% of
unvaccinated sexually-active teens.
Of course, vaccinated teens had much lower rates of
type 16 & 18 infection than did unvaccinated teens, but that
wasn't enough to offset the vaccinated teens' higher rates of
infection with other high-risk types. Because most high-risk HPV
infections are other types, a slightly higher percentage of
vaccinated teens had high-risk HPV infections than did unvaccinated
teens.
Obviously, vaccination does not protect against
infection with high-risk strains of HPV!
That also suggests an obvious question:
If it is true that
"girls who received the
vaccine did not begin sexual activity earlier than their
unvaccinated peers [and did not] engage in higher risk
behavior," then what could explain their higher HPV infection
rates?
Additionally, Gardasil has its own risks. The number of deaths and injuries is
small compared to the number of patients, but it could eventually
be dwarfed by the number of future cancer deaths, if some patients
mistakenly believe that vaccination means they needn't get regular
exams & pap smears.
Please make sure that, in future CBS
reports, you tell viewers that Gardasil cannot reliably protect
them from cervical cancer. It will not eradicate that disease,
nor even come close. The best we can hope for is a modest reduction
in the number of cases, and even that is uncertain.
Over-hyping the potential of Gardasil to combat
cervical cancer could end up killing more patients than the vaccine
saves.
Sincerely,
Dave
On Thu, Jun 20, 2013 at 1:16 PM,
Dr. Holly Phillips wrote:
Dear
David,
Thanks so much for
watching the broadcast and CBS. Even though the practice of
medicine is my greatest joy, I also very much enjoy my role
as a journalist, not just to impart information but to incite
spirited discussion as well.
The information I
reported on came from the large scale CDC study released
yesterday, and published in the Journal of Infectious
Diseases. Here's a link to the original
article.
http://jid.oxfordjournals.org/content/early/2013/06/18/infdis.jit192.full?sid=2e3ff264-cfb4-40a9-b1b8-245bf2623574
One aspect of the
data I found particularly interesting was that girls who
received the vaccine did not begin sexual activity earlier
than their unvaccinated peers, nor did they engage in higher
risk behavior. The study did not address compliance with
regular gynecological exams and pap smears as they enter
adulthood. I do hope that all women continue to do both
vigilantly.
All the
best,
-H
-----Original
Message-----
From: David Burton
To: Dr. Holly Phillips
Sent: Thu,
Jun 20, 2013 12:18 pm
Subject: HPV / Gardasil
Dear Dr.
Phillips,
I was shocked to
hear you interviewed on CBS This Morning about
the Gardasil vaccine. You told listeners that
this vaccine can "eradicate" the disease, and
that people who get the vaccine will never get
HPV-caused cancers.
That is wildly
inaccurate, and deadly
dangerous.
Gardasil
protects against only a few strains of HPV.
According to a U. Washington study (Winer, et al, 2006, Table
2), most
recent HPV infections with "high risk"
oncogenic strains of HPV are strains that
Gardasil does nothing to protect
against.
That study made
headlines because, unlike most other studies,
they found that condoms somewhat reduce the
risk of HPV infection. But the study's most
important result never made the
headlines.
HPV types 16,
18, 26, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58,
59, 66, 67, 68, 73, and 82 have all been
identified as high-risk oncogenic strains, and
Gardasil only protects against types 16 and 18.
Those two types accounted for just 14 out of 78
high-risk infections detected in the U.
Washington study. 82% of the high-risk
infections were with HPV strains that Gardasil
does not protect
against.
The relative
prevalence of different HPV strains in the
general population varies considerably, both by
location and over time, and cervical cancer
usually takes a long time to develop. Today's
cervical cancer cases result from the HPV types
which were prevalent decades ago -- and
those are the strains that Gardasil is
designed to protect against, not the numerous
other high-risk strains which now cause most
high-risk HPV infections.
Gardasil is like
the Maginot Line: a defense designed for the
previous war, but inadequate for the current
one.
If, after
hearing your report, young women who got the
Gardasil vaccine before they became sexually
active erroneously think that they are safe
from cervical cancer, they may forgo PAP
smears, and, paradoxically, be at
greater risk of dying from cervical
cancer than if they'd never gotten the vaccine
at all.
PLEASE tell CBS
listeners the truth:
- Gardasil only
protects against 2 of the 19 (so far) known
high-risk strains of
HPV,
- The great
majority of high-risk HPV infections are with
strains that Gardasil does not protect
against, and
- Sexually
active women are at risk for cervical cancer
and other cancers, and still need to get
regular PAP smears, regardless of whether or
not they've been vaccinated with
Gardasil.
If people
believe the myth that Gardasil vaccination
prevents all high-risk HPV infections and
reliably protects them from cervical cancer,
some of them will die as a
result.
Sincerely,
David A.
Burton
Cary,
NC
M: 919-244-3316
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