Skepticism about science and medicine

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Posts Tagged ‘cervical cancer’

HPV vaccines: risks exceed benefits

Posted by Henry Bauer on 2017/07/09

“Vaccination” is publicly argued in black/white, yes/no fashion, as though one had to be either for or against ALL vaccinations. But the fact is that the benefits of some vaccinations far outweigh the dangers of occasional harmful “side” effects whereas that is not clear with other vaccines. Polio vaccine, for example, seems to have been wonderfully effective and is still so in many countries; on the other hand, in regions where polio is no longer endemic, the risk of contracting polio from oral vaccine exceeds the danger of contracting it when not vaccinated (see links near the end of What to believe? Science is a red herring and a wild-goose chase).

Immune systems are complex and not fully understood, and there are individual variations galore — as when one of my friends came down with shingles shortly after being vaccinated against shingles. (The doctor of course assured him that the outbreak would have been more painful had he not been vaccinated; an ex cathedra assertion without possibility of verification.)

I was reminded of the issue of HPV vaccination by a brouhaha in Europe between the European Medicines Agency (EMA) and medical practitioners and researchers who had come across a substantial number of cases of harm seemingly following HPV vaccination, harm specifically in the form of chronic autoimmune ailments. Since vaccination affects the immune system, such an undesired effect in some individuals seems perfectly plausible.

The Nordic Cochrane Center exists for the purpose of evaluating the evidence underlying medical practices. The Cochrane Center and others have been campaigning for many years to have the data from clinical trials made available to all researchers (1). Last year it lodged a complaint (2) against EMA for conflicts of interest with drug companies exacerbated by the secrecy of discussions that led to criticism of physicians’ reports about autoimmune symptoms appearing after vaccination against HPV. That secrecy is truly extraordinary, virtually an admission of conspiracy: “experts who are involved in the process are not named and are bound by lifelong secrecy about what was discussed” (3).

An EMA publication had severely criticized publications by Louise Brinth and others who had published reports of autoimmune symptoms following vaccination (4); Brinth has delivered a blistering response to the EMA insinuations (5).

The supposed benefit of vaccinating against HPV is to decrease the risk of certain cancers, primarily of the cervix. There are perhaps a hundred types of HPV, of which about 40 are sexually transmitted, and two to four of these seem to be statistically correlated with cancer:
“High-risk HPV strains include HPV 16 and 18 . . . . Other high-risk HPV viruses include 31, 33, 45, 52, 58, and a few others. Low-risk HPV strains, such as HPV 6 and 11, cause about 90% of genital warts, which rarely develop into cancer” (What is HPV?).

HPV infections are the most common sexually transmitted infection: “HPV is so common that nearly all sexually active men and women get the virus at some point in their lives” (Human Papillomavirus (HPV) Statistics). Thus most infections do not lead to cancer, which might induce thought about what “cause” could mean in this context. About 4% of Americans are infected each year with a “high-risk” strain, about 6 million women (USA population is about 320 million, so roughly 160 million women). There are only about 12,000 cases annually of cervical cancer: thus only about 1 in 500 of even “high-risk” infections is associated with this cancer. Thus vaccinating about 500 “high-risk” women might prevent 1 cervical cancer; NNT (number needed to be treated for 1 person to benefit) = 500.

On the other hand, there appears to be about 1 chance in 200 of an adverse effect from vaccination by Gardasil (Gardasil and the sad state of present-day medical practices); about 8% (~ 1 in 12) of adverse events are “serious”, so there’s about 1 chance in 2500 of a serious adverse event. NNH (number needed to be treated for one person to be seriously harmed) = 2500.

For any medical treatment to be desirable, it should be necessary to treat many more people to harm a single one than the number needed to be treated to benefit a single person; NNH should exceed NNT by a substantial amount.
The numbers just mentioned yield a ratio of only 5 — in other words, there’s something like a 1 in 5 chance, 20%, that HPV vaccination would harm rather than benefit. But those numbers apply if only those women infected with high-risk strains are vaccinated. However, the advocates of HPV vaccination, which includes official agencies in the USA and some other countries, recommend HPV vaccination for all girls. That increases NNT by a factor of 25 and reverses drastically the benefit/cost ratio: It is 5 times more likely that an HPV vaccination will result in a serious adverse event than that the vaccination prevents a case of cervical cancer — even if HPV is the actual cause of cervical cancer, which remains to be proved beyond a mere weak statistical correlation.

It is simply not known whether HPV causes cancer at all. Certainly it does not always cause cancer. An extended article on the invaluable website that debunks urban legends is judicious on this matter by pointing out that the claimed association of HPV vaccination with autoimmune symptoms is only speculative. On the other hand, it also concludes in an update of 12 June 2017:
“An earlier version of this story incorrectly stated that countries with high HPV vaccination rates show declines in cervical cancer diagnoses. Both Gardasil and Cervarix have demonstrated efficacy in preventing HPV infections that cause cervical cancer, and evidence suggests declines in precancerous lesions and other abnormal growths as a result of HPV vaccination. There is debate over evidence for declines in cervical cancer diagnoses — as well as over how much time it would take after the introduction of the vaccine to see any effect on cancer diagnoses” [italics added].

The vaccines against HPV are successful against HPV — but it has never been proved that HPV (or the four strains of it supposed to be associated with cervical cancer) actually causes cancer. Since the rate of HPV infections exceeds the rate of cervical cancer by a huge amount, any “causative” action of HPV must be very indirect, especially since only a small percentage of HPV strains shows even a statistical association with cancer.
Recall that the usual test of “statistical significance” in medicine is p ≤ 0.05, meaning that there is less than a 5% chance that the association is owing only to chance. If there are 100 possible associations, about 5 of them will seem significant even though they are not, being picked out purely by chance because of the (weak!) criterion for statistical significance (6). If there are 100 strains of HPV, then at p ≤ 0.05, purely by chance about 5 strains will seem to be correlated with cervical cancer — or with just about anything else.
Before accepting any role fort HPV in cervical cancer, one should want a demonstration of the mechanism of the claimed causative effect.

(1) “Opening up data at the European Medicine”, Peter Gøtzsche & Anders Jørgensen, British Medical Journal, 342 (28 MAY 2011) 1184-6; “EMA must improve the quality of its clinical trial reports”, Corrado Barbui , Cinzia Baschirotto & Andrea Cipriani, ibid., 1187-9
(2) Complaint to the European Medicines Agency (EMA) over maladministration at the EMA, 26 May 2016
(3) “Complaint filed over EMA’s handling of HPV Vaccine safety issues”, Zosia Chustecka, 5 July 2016
(4) “Suspected side effects to the quadrivalent human papilloma vaccine”, Louise Brinth, Ann Cathrine Theibel1, Kirsten Pors & Jesper Mehlsen, Danish Medical Journal, 62 (#4, 2015) A5064
(5) “Responsum to Assessment Report on HPV-vaccines released by EMA November 26th 2015” by Louise Brinth, MD PhD, Syncope Unit, Bispebjerg and Frederiksberg Hospital, Copenhagen, December 15th 2015
(6) For a thorough discussion of the pitfalls of interpreting p values, see Gerd Gigerenzer, “Mindless Statistics”, Journal of Socio-Economics, 33 (2004) 587-606.

Posted in medical practices, prescription drugs, science policy, unwarranted dogmatism in science | Tagged: , , | 2 Comments »

Trust medical science at your peril: Correlations never prove causation

Posted by Henry Bauer on 2016/06/28

It was a long-known empirical fact that poverty, vagrancy, criminality, and apparently deficient intelligence all correlated with heredity to a considerable extent; they all ran in families and clans. The scientific confirmation that characteristics of animals are passed on from generation to generation, and the Darwin-Wallace explanation of evolution by natural selection of the fittest, made it possible to understand those aspects of human society. It was an obvious, scientifically sound conclusion that human societies could be steadily improved by restricting reproduction of the less fit and expanding the fertility of the fittest. Hence the eugenics movement, promoted by the most progressive, liberal people who were also the best educated, with an apparently justified faith in the reliability of what was at the time the most up-to-date the scientific knowledge (Trust science at your peril: Beware of scientism and political correctness). Those circumstances led to forced sterilization of tens of thousands in America and reinforced Nazis in their doctrines and practices of mass killing of the unfit — Jews, gypsies, homosexuals (Edwin Black, War Against the Weak, 2003).

Only in hindsight did the flaws and errors of the earlier scientific consensus become clear. We now appreciate that environmental and developmental influences can modify heritable traits quite dramatically. “Ill-bred” can be the result of social, economic, environmental factors as much, perhaps even more than any pre-ordained verdict of genetics; and “well-bred” individuals can spring from what might seem the least promising hereditary stock. In other words, the observed correlation between undesired social characteristics and clans was misinterpreted through neglecting the variable of environmental effects.

One lesson to be drawn is that bad science, wrong science, what some even call pseudo-science, can remain the accepted scientific consensus for decades, even in quite modern times, say, the middle of the 20th century. It is unlikely that a mere half-a-century later our societies have become immune from assuming that a mainstream scientific consensus must be true to Nature. Nothing guards our times from treating unjustified, misguided scientific claims as good science.

Unwarranted claims coming from scientists continue to be accepted if they appear minimally plausible and if they are consistent with world-views and vested interests of financial, social, or political powers.

The most sweeping lesson that remains to be learned is that correlations must never be taken as demonstrating a cause-and-effect relationship: there might always be in play an unsuspected variable. One of the earliest axioms taught in Statistics 101 is that correlations never prove causation. The evident correlation between biological kinship and undesirable behavioral traits was not a cause-and-effect relationship.

Many or most people have never learned that basic truth that correlations are not causes. Many others “know” it as a generalization but fail to apply it in specific instances, when an evident correlation could plausibly reflect cause and consequence — just as a genetic basis for undesirable characteristics seemed quite plausible to educated and expert people not so long ago.

Indeed, a large swath of modern medical practices is based on mistaking mere correlations for evidence of causation (“Correlations: Plausible or implausible, NONE prove causation”). For example:

HPV and cervical cancer

The National Cancer Institute offers a great deal of information about this:

Human papillomaviruses (HPVs) are a group of more than 200 related viruses. . . Sexually transmitted HPV types fall into two categories:
— Low-risk HPVs, which do not cause cancer but can cause skin warts (technically known as condylomata acuminata) on or around the genitals, anus, mouth, or throat. For example, HPV types 6 and 11 cause 90 percent of all genital warts. HPV types 6 and 11 also cause recurrent respiratory papillomatosis, a less common disease in which benign tumors grow in the air passages leading from the nose and mouth into the lungs.
— High-risk HPVs, which can cause cancer. About a dozen high-risk HPV types have been identified. Two of these, HPV types 16 and 18, are responsible for most HPV-caused cancers. . . .
>> Cervical cancer: Virtually all cases of cervical cancer are caused by HPV, and just two HPV types, 16 and 18, are responsible for about 70 percent of all cases . . . .
>> Anal cancer: About 95 percent of anal cancers are caused by HPV. Most of these are caused by HPV type 16.
>> Oropharyngeal cancers (cancers of the middle part of the throat, including the soft palate, the base of the tongue, and the tonsils): About 70 percent of oropharyngeal cancers are caused by HPV. In the United States, more than half of cancers diagnosed in the oropharynx are linked to HPV type 16 (9).
>> Rarer cancers: HPV causes about 65 percent of vaginal cancers, 50 percent of vulvar cancers, and 35 percent of penile cancers (. . . .) Most of these are caused by HPV type 16.

The Centers for Disease Control & Prevention offer advice on avoiding HPV cancers:

— Bivalent, quadrivalent and 9-valent HPV vaccines each target HPV 16 and 18, types that cause about 66% of cervical cancers and the majority of other HPV-associated cancers in both women and men in the United States. 9-valent HPV vaccine also targets five additional cancer causing types (HPV 31, 33, 45, 52, 58) which account for about 15% of cervical cancers. Quadrivalent and 9-valent HPV vaccines also protect against HPV 6 and 11, types that cause anogenital warts.
— Quadrivalent and 9-valent HPV vaccines are licensed for use in females and males; bivalent HPV vaccine is licensed for use in females.
What percent of HPV-associated cancers in females and males are caused by the 5 additional types in the 9-valent HPV vaccine?
— About 14% of HPV-associated cancers in females (approximately 2800 cases annually) and 4% of HPV-associated cancers in males (approximately 550 cases annually) are caused by the 5 additional types in the 9-valent HPV vaccine.

What evidence is there for these extremely specific claims of causation?

None, actually. The cited facts are merely that the stated strains of HPV have been detected in those proportions of those cancers. Those correlations don’t begin to indicate causation.

It may be worth recalling that the Centers for Disease Control & Prevention in the early 1990s had officially stated, on the basis of the same sort of data (epidemiology, i.e. correlations), that cervical cancer was an AIDS disease, caused by HIV.

One may sympathize with medical researchers for the impossibility of conducting experiments that would be capable of proving cause-and-effect; ethical, legal, and moral restraints make it unfeasible to use human beings as experimental guinea pigs. There would also be practical barriers: To determine whether a given treatment, in this case a vaccine, actually prevents cancer, a clinical trial would be necessary that spanned over decades and enrolled large numbers of human guinea-pigs, some of whom (controls) would not get potentially-cancer-preventing vaccine.

However, the inability to obtain proof does not justify proclaiming as fact, as these official agencies do, causative relations that are no more than speculation based on statistical correlations.

[The vaccines] “Gardasil and Cervarix have not been shown to be of any significant health benefit. They have been demonstrated to cause serious injuries. It’s scandalous that they were ever approved, and it’s scandalous that they remain on the market.

And they are far from alone on those scores among new prescription medications introduced in the last couple of decades” (Deadly vaccines, 2013/04/17

Alzheimer’s Disease

Sleep disorders may raise risk of Alzheimer’s, new research shows
Sleep disturbances such as apnea may increase the risk of Alzheimer’s disease, while moderate exercise in middle age and mentally stimulating games, such as crossword puzzles, may prevent the onset of the dementia-causing disease, according to new research to be presented Monday

A daily high dose of Vitamin E may slow early Alzheimer’s disease

Again, these are correlations speculated to be possible causes.

Semantics no doubt plays a role. One could report that sleep disorders, and lack of vitamin E, seem to be associated with a risk of Alzheimer’s. Medical jargon puts it like this: “sleep disorders, and lack of vitamin E, are risk factors for Alzheimer’s”. Then the media and public conclude that “risk factor” means something that tends to cause the associated effect.

See also “60 MINUTES on aging — correlations or causes?


It is not feasible to test treatments for chronic conditions by actual outcome, because one would have to wait a couple of decades to determine whether regimen A or drug B reduces morbidity and mortality apparently associated with high blood pressure, or high cholesterol, or high blood sugar, or low bone density, etc. All those are statistically correlated with increased morbidity and mortality. They are risk factors.

Present-day medical dogma makes them biomarkers for cardiovascular disease, diabetes, bone fracture, in other words indicators of whether the disease is present. But that is tantamount to making those quantities measures of actual risk, in other words regarding them as measures of what causes those ailments, in other words equating risk factors with causes.

Official reports, however, as well as the many studies on which those reports are based, find that biomarkers are not proper measures of risk after all. See:

“Everyone is sick?”

“‘Hypertension’: An illness that isn’t illness”

“Cholesterol is good for you”


Unfortunately, they were not joking

“Magical statistics: Hearing loss causes dementia”


The overall lesson:

“Don’t take a pill if you’re not ill”

The ignorant acceptance of correlations as capable of demonstrating causation is greatly reinforced in medical matters by the pharmaceutical industry, which sells drugs as palliatives and preventatives based on nothing more than correlations with biomarkers.

Posted in conflicts of interest, consensus, media flaws, medical practices, prescription drugs | Tagged: , , , , , , , | 5 Comments »