Thursday, April 20, 2006

Correlation is *NOT* causation

One of my guilty pleasures is my subscription to Better Homes and Gardens magazine. Nothing contentious about that – I like recipes and decorating and gardening ideas. But this month's issue had an insert in it that I just couldn't ignore. Before I go full-on rant here, I need to explain a little where I'm coming from.

It was recently brought to my attention that I've been quieter about my "former life" than I thought I had. So to explain my perspective, and to assure you all that I'm not a total raving conspiracy theorist lunatic, here's the nutshell version: before I became the happy hermit housewife you all are familiar with, I went to pharmacy school. The only degree you can get anymore to be a pharmacist is a PharmD – Doctor of Pharmacy. To do so requires enrollment in a 6-year PharmD program (which I did), or a 4-year degree in a school with a cooperative arrangement with a pharmacy school for completion of the last 2 years. The schooling is 5 years of classes – 2 years "regular" undergrad work and 3 years of "professional" classes – plus 1 year of clinical rotations, which are like medical internships, but you pay tuition instead of getting a salary. I completed my 5 years of classes up till the end of the very last semester, then quit before clinical rotations. I was already working in a pharmacy, doing everything except check prescriptions before they went out the door. The stress of school nearly killed me, and having to actually do the job definitely would have. Unfortunately, I had to have what I'm pretty sure was a nervous breakdown before I could admit to myself that I needed to get out. So I have all the knowledge and student loans, none of the stress or income or degree.

So yes, for the topic I'm about to dig into, I know what the hell I'm talking about. And the topic is a serious one – cervical cancer.

The insert I got was for an ad campaign called "Tell Someone" – here's the link provided: Before I get into the details of my beef with this campaign (and the underlying assertion), please note who this site is run by: Merck. And I will state it here, and reiterate it later – Merck has developed and is working on FDA approval for a HPV vaccine. Just so you have an inkling of the motivation here.

Just for thoroughness, here are three brief generalized paragraphs – one on HPV, one on cancer, and one on viruses.

HPV is the abbreviation for Human papillomavirus – this is the virus that causes genital warts. Much like genital herpes (and ANY virus), this virus can be treated and controlled, but not cured.

Whenever a cell divides or DNA is replicated for any reason, we have an enzyme that acts as a "spellchecker" to make sure that all the little nucleotides are copied verbatim. Sometimes, this spellchecker screws up. Many times, the resulting "mis-copies" are inert – the error doesn't cause any change in cellular development. Sometimes, they do cause something to happen, and the result is benign – the error causes a little lump of incorrect, but not *harmful* tissue to develop. And sometimes the errors cause a malignant growth – incorrect tissue that replicates and can break off and spread through the body. Considering how many time our spellchecker enzymes get things right, the errors are almost statistically insignificant. Except that those errors occur in a conscious being that knows what has happened and the consequences of that one little oversight, and fights to fix it however possible.

Viruses are tricky little thingies. It has still not been determined if they can even be considered "living" or "non-living" things (the wikipedia entry, should you care to read up: Basically they come in and commandeer your cells to replicate their genetic material. I think we (people) tend to think of them as living things because in many cases they are our adversaries and attackers. It's much easier, conceptually, to battle a creature that's intent on doing us harm or even kill us. And when they invade, we are often fighting them for our lives.

I think I should mention that I am very much pro-vaccines. There's a reason polio isn't the menace it once was, and that things like measles and mumps are pretty much a thing of the past. This is NOT a diatribe against vaccinations.

All that being covered, I am totally willing to entertain the idea that a virus (non-specific) can increase the likelihood of developing cancer (non-specific). In general, the more cellular activity occurring in your body, the more likelihood of "spellcheck" errors. Look at skin cancer – the more you damage your skin (via tanning, deliberate or otherwise), the more repairs your body has to come in and make. This means making new, healthy cells, which requires cell division/production. Which means potential errors. Hence tanning and burning (we all know by now that a tan is your body telling you your skin is damaged, right?) being one of the main causative factors leading to skin cancer. I know that's a major oversimplification, but you get my point. And an outside entity that acts directly on our genetic material? Of course it's potentially carcinogenic!

For some time now, it has been stated that having HPV increases a woman's likelihood for developing cervical cancer. Let me first say that the science behind this claim/notion is dubious at best. There are any number of women who develop cervical cancer who have never had HPV – I know one personally! And even more women with HPV who never develop cervical cancer. This alone should bring doubt into the mind of any rational person about HPV "causing" cervical cancer. Also, this so-called correlation doesn't take into account several factors, the primary one being that women who contract HPV are statistically far more likely to have contracted one or more other STDs in their lifetime.

My issue with the HPV connection is this: yes, the HPV directly acts on our DNA, so it does have more potential to cause cancer than other STDs. But any STD causes an immune reaction, which means increased cellular activity in that area. And, therefore, more potential "spellchecker" errors than a totally healthy vaginal/uterine/cervical area would face. Not only that, but an otherwise "normal" or "healthy" woman could have a spontaneous error caused/influenced by nothing, or chemicals in the household or workplace, or radiation/chemo treatment for an unrelated cancer. There are SO many factors involved in the development of a cancer, and it makes me beyond angry that anyone would try to oversimplify things this way. But now, after developing their marvelous vaccine, Merck is trying to convince people that HPV causes cervical cancer??? How many women currently neglect their annual Pap tests? I know I'm not on top of it like I should be. And although I'm sure even vaccinated women will be told to get their annual exams, how many will think they're protected, and not bother? Or put it off till it's too late?

As I said before, I am definitely pro-vaccine. I think the development of an HPV vaccine would be a major boon to men and women! Regardless of any possible cancer connection, anything we can do to improve the overall health of humanity is a good thing, in my opinion. And I think a campaign to inform people that an HPV vaccine is (or will soon be) available is a great idea. It's one of the least talked-about STDs out there, mainly because of the "ick" factor. I only know one woman who has ever shared with me that she had it (got it from a cheating bastard spouse), and she was only comfortable sharing about it after I started ranting on this subject, and it came up. Women talk about a lot of things, but STDs aren't high on the list. But to promote it under the auspices of preventing cancer??? That's negligence, as far as I'm concerned. And I shudder to think of the number of women in 20 to 30 years who will agree with me.


Sali said...

I'm with you on this. It's amazing the choice of words the pharmaceuticals have come up with to market this new vaccine. The perfume marketing teams have nothing on them.

risa said...

THANK you. i've been astonished at the number of ppl who already think HPV causes cervical cancer. i know a few men who have HPV who are afraid to date women past a certain point, thinking they're going to *give* them cervical cancer. it's deeply painful to watch.

Anonymous said...

Some strains of HPV DO cause cancer, but not all. Not all people with HPV get cervical cancer, but 99.9% of people with cervical cancer have/had HPV. Drug companies aren't making it up... check out legit organizations yourself.

tess said...

I am HPV positive with cervical cancer (stage 1 microinvasive). I am all for the campaign, and personally I would like to see a vaccine... I wouldn't have cancer if there had been one years ago ;)
The facts are the not all strains of the virus (and there are hundreds) cause cancer... but there are genetic factors involved as well... but the high risk HPV virus can and does sometimes cause cancer. I am a witness to that.

Trina said...

Tess, I feel for you and am so sorry for the struggle you're facing. Like I said, I'm not against the idea that it can increase the lieklihood. But the statement that it "sometimes causes and sometimes doesn't" inherently argues against causation. And calling the vaccine a "cancer vaccine" is wrong.

Trina said...

anon - I have seen those sites, and I understand that there are a number of legitimate organizations and respected scientists who believe this to be true. I'm saying the science behind this conclusion is faulty. Just as the science behind the determination that the Feline Leukemia Virus (as it has been named) is the cause of feline leukemia is faulty (whole other topic).

The second source *you* posted says right on its home page "An HPV infection rarely leads to cervical cancer". I'd like to know where you get that "99.9%" figure as well.

And again - I'm not saying that the drug companies are making up the correlation. I'm saying that they're being manipulative and grossly generalizing in putting it out there that an HPV vaccine will protect women from cervical cancer. It might help, but it will never be an absolute.

Trina said...

Risa, I feel for those men, I really do. My friend who contracted HPV was *terrified* that she was going to get cervical cancer because she had HPV. It drives me crazy that people aren't being informed properly, hence the rant.

Trina said...

Sali, you ain't kidding! I screamed at the Ambien (and other Rx sleep meds) commercials for *years* b/c they said using sleeping pills improperly could cause dependence. Never mentioned that using them *properly* can too! They finally fixed the ads a year or so ago. I wonder how many lawsuits *that* took!

Anonymous said...

I have the very early stages of cervical cancer, it runs in my family. I was tested HPV negative. I have a minor in Microbiology from the University of Texas and am dismayed by the irresponsible advertising put out by Merck.

Anonymous said...

Frankly, I couldn't care less if Merck makes billions of dollars on a vaccine for HPV. In fact, I think they would deserve every last penny. If a man or a woman with HPV has sexual contact with a female without HPV, they are increasing the likelihood that their female partner will develop cervical cancer, and although I feel badly for those people who are carriers, that is simply what the research has indicated. "A virus—the human papillomavirus, or HPV—causes almost all cases of cervical cancerpapilloma virus or HPV (". So yes, men who have HPV SHOULD be worried about increasing their partner's risk of developing cervical cancer. They are being responsible. If they want help with how to disclose their HPV status, they can go to takes it a step even farther, stating
"Women who get cervical cancer have had past infections with HPV. High risk types of HPV can cause changes in the cells covering the cervix that make them more likely to become cancerous in time. But, on the other hand, the vast majority of women infected with these viruses do NOT develop cervical cancer. So there must be other factors at work". In other words, you are completely, right, correlation does not equal causation. However, no experimental studies, with the blind or double blind techniques can possibly be done with cervical cancer. In other words, we can't take a bunch of women, randomly assign them to groups, then group a gets to be infected with HPV and group B doesn't, and then let’s see what happens! So we have to live with the limitations of correlation, because we cannot gather experimental information.

New research is working towards developing a vaccine to prevent HPV infection. This research is promising and could result in the complete prevention of cervical cancer. The vaccine may even mean the end of smear testing (" I do agree that pharmaceutical companies play on our fears, and use, ah, creative language. However, in this case, I don't think the link between HPV and cervical cancer is unfounded. The truth is that the majority of women with cervical cancer do have HPV, and although, thankfully, most HPVs go away, some don't. As you have said, Trina, we should all be for eradicating HPV.

Heather said...

I developed cervical cancer last year at age 32. I also tested postive for HPV. My doctor told me that there are many strains of HPV, but only 3 strains increase a woman's likelihood of developing cancer. I tested positive for one of those strains.

My doctor told me that the ONLY way to develop cervical cancer is to have this type of HPV. She was so adamant about this that I believe this was her way of telling me that I deserve it, that I brought it upon myself with my dirty, dirty behavior.

I was initially excited by the tell someone campaign, but felt strange when I saw it was sponsored by Merck.

Regardless, I am for the vaccine. First, why not eradicate HPV? Is there a reason we need it to go unchecked?
Second, if there is any chance that the vaccine could eradicate cervical cancer, the price of ignoring this chance is too great.

Trina said...

Heather - I absolutely agree with you about eradicating HPV! Why on earth would we *not* want to do so? And if it helps prevent cervical cancer in even ONE person, that's worthwhile in my opinion.

My only problems are:
1) That many women (such as yourself) are being or have been made to feel like they've brought something terrible like cervical cancer on themselves when no direct causation has EVER been established, despite what people are being *led* to believe.


2) That people really will think that getting this vaccination will be a 100% prevention method for cervical cancer.

I truly wish that they were approaching this thing from the chicken pox/pneumonia/hepatitis angle: put it out there that we're trying to prevent and/or eradicate a nasty disease that can have long-term repercussions. That would be *responsible* goal-setting and publicity. But stop telling people that this is a cancer vaccine, PLEASE!

John Deaux said...

I'm a male who might have HPV. I don't know because I've been told that there is no test for males. My ex tested positive for it but I don't know what strain. I am now wanting to move on to a new relationship but not sure if I have it and damn sure I wouldn't want to pass on something that might lead to cancer. What do I do? Am I doomed to singleness? Seems like any woman would drop me in a miute if I told them. Any help ladies?