I was puzzled to read that a study showed an increase in cancer if one takes a certain medicine for one’s blood pressure.

The devil is in the details, of course, but the headlines blaring out cancer risk, but the details in these articles admit that the risk is tiny. From Reuters:

Overall, they found that patients taking the drugs had 7.2 percent risk of having a new cancer diagnosis, compared with 6 percent risk for patients in the control groups.

So how was the study done?

It was a “metanalysis”, which is where the writers pick a bunch of articles and pool the data.

This type of study is claimed to be “scientific”, but all you need is one badly done article and voila, instant problem that might not be there.

Nissen said the study is limited by the fact that the trials were not designed to look at cancer risks.

A second problem is that they just happened to choose a subset of blood pressure drugs that are called ACE 2 inhibitors, that block angiotensin. ACE 1 drugs are cheap (the “prils”, e.g. lisinopril, enalopril), but ten percent of folks taking them develop a cough, so a lot of docs use the more expensive ACE 2 medicine (the “sartans”, e.g. valsartan).

Of course, if you have a high risk patient, whose insurance covers the medicine and who is not good at coming back to your office, maybe you will start with the ACE2 first, but most of us start with ACE 1, and keep an eye out for the cough or the “I can’t get rid of this tickle in my throat” side effect that patients don’t usually blame on their medicine.

So was there a ‘hidden agenda” behind this, to save money?

Nissen said … the drugs are often overprescribed because of aggressive marketing, and patients might fare just as well taking inexpensive ACE inhibitors instead.

So what is wrong with the reporting?

The little fact that blood pressure is a major risk for dying of stroke, heart attack, and renal failure.

And one result of this bad reporting is that some folks will simply stop their blood pressure medicine and die of a stroke or heart attack.

I am old enough to remember when folks with high blood pressure died. Here in the Philippines, we still have too many middle aged folks limping or paralyzed from untreated high blood pressure. Our government is aggressively working to lower the price of the most common blood pressure medicines so the poor can afford it. One common medicine is only 5 dollars for a month’s treatment, but when you only earn 3 dollars a day, that might be too much for the family budget.

In the US this is rarely a problem, but I do agree the ACE 2 inhibitors are a bit expensive compared to other medicines.

For routine blood pressure, there are lots of medicine to pick and choose from, including older medicines that are a lot cheaper.

ACE 1 are cheaper (20 cents a pill here) than ACE 2 (80 cents a pill) if you don’t develop that cough.

So why use them?

You see, although ACE inhibitors can cause kidney failure, for diabetics, they have a protective effect on the kidney, delaying the onset of “microproteinemia” (an early sign of kidney damage) and delay the renal failure that kills so many diabetics.

Which brings us to the question not mentioned in the Reuters article.

Was  the population biased toward minorities who are more prone to develop cancer and diabetes and blood pressure? Blacks who don’t trust the medical system and poor folks whose diet and smoking history might be higher than that of the average upper class white yuppie might not have their cancers prevented or screened as closely.

Why does this matter? Well, although there is a tiny increase in all cancers, the only type of cancer that was found in increased numbers was lung cancer.

When they looked at cancer types, only lung cancer stood out, with 0.9 percent of patients taking blood pressure drugs developing a new lung cancer compared with 0.7 percent of patients in the control arm.

Reading the article brings up even more questions, because although the patients had a “follow up of at least one year”, the dirty little secret is that many cancers are present for several years before they are diagnosed.

So could this group of medicines increase cancer, or maybe affect the immune system so that cancerous cells grow instead of the body’s immune system destroying them? Or could the immune system of those taking this more expensive medicine (which is the “drug of choice” for diabetics) be affected by the disease for which they are taking the medicine in the first place?

So although most of the headlines on Google’s news hint at the problem, one wonders why the headlines don’t mention that this “cancer risk” conclusion is not found in the original article, which states:

Given the limited data, it is not possible to draw conclusions about the exact risk of cancer associated with each particular drug. These findings warrant further investigation.

Please, please don’t throw away your pills because of bad reporting. The small risk, if any, is a lot lower than your risk of heart attack or stroke.

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Nancy Reyes is a retired physician living in the rural Philippines. Her website is Finest Kind clinic and fishmarket, and she writes medical essays at HeyDoc Xanga blog.

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