Map of life expectancy at birth from Global Education Project.

Friday, August 30, 2013

It's an epidemic!

OMG! The incidence of thyroid cancer has tripled in the U.S. in the past 30 years, from 3.6 cases/100,000 to 11.6. Is it radioactive fallout? Pesticides? Vaccination? Fluoridation?

Nope. It's CT scans. And you can relax. They aren't causing thyroid cancer, they're finding abnormal cells which in the past, nobody would have detected. But, as Brito, Morris and Montori tell us at the linked article (which I don't think you can read but that's okay, I'll tell you what's in it), they aren't actually cancer after all.

There are four different kinds of thyroid "cancer," the most common of which is called papillary carcinoma. Guess what? 99% of people with papillary nodules less than 20 mm in diameter will be alive after 20 years. It turns out that at least 1/3 of people who die of other causes have these lesions, which were never detected.

It used to be that thyroid cancer would be diagnosed when a person presented with symptoms or palpable nodules. Now, when people get CT or MRI scans to investigate coughing or neck pain, 16% of the time they find nodules in the thyroid, most of which are less than 15 mm in size.

Then what do you think happens? The doctor says, "You have thyroid cancer," and the person has surgery to remove part or all of the thyroid, which cost $416 million in 2006. They have to take thyroid replacement pills for the rest of their lives, and it's difficult to adjust the dose properly. Some have more severe complications. And, contrary to recommendations, 2/5 of people get radioactive iodine which makes it easier to do follow-up imaging but, er, causes cancer.

Well, at least we're saving lives, right? You already guessed the answer. The death rate from thyroid cancer in the past 30 years has stayed exactly the same. Rarely, people have opted not to have surgery and to just be followed carefully. In an observational study, of 340 people who made this choice, none died. That would be zero. In 31 patients, the nodules did enlarge, and 18 of them ultimately chose surgery. Thirteen did not, and in 7 of them, the tumors subsequently shrank.

Draw your own conclusions.

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