Tuesday, August 25, 2009

Full body scans and cancer screening...

Hi all -

Here's a question which comes up commonly during annual physical exams:

"How can I get scanned/ tested for cancer? I want a full-body scan to see if I have brain tumors or any kind of cancer. Do I need to show symptoms first, or can I simply request a test?"

The scan you're talking about is probably something you've seen advertisements for, which is a full-body MRI or CT scan. What this scan promises is the reassurance of health, but what it likely provides is just a big bill and a lot of needless worry.

Cancer is obviously very scary and dangerous, but screening for it is one of the main things we do as part of primary care and annual physical exams. With regular screening, we can catch it early and hopefully "nip it in the bud" before it becomes advanced. But the kind of screening we do is called"age appropriate cancer screening." What we know is that the risk of most cancers increases in general with age (and obviously other risk factors specific to those cancers), and for this reason we have guidelines as to when it becomes reasonable to start screening for these cancers, but the starting ages vary. For instance, we start screening for cervical cancer at age 21, 35 for breast cancer, 50 for colon cancer, 50 for prostate cancer. All these ages can be affected by individual risk, such as a positive family history, or risks that are individual to that cancer - your doctor can discuss these with you if you are worried.

There are some cancers where the guidelines are rather "grey" in that no studies have proven that it is cost-effective to start screening for them at agreed-upon age (by major groups, such as the American Cancer Society), such as lung cancer. These cancers are screened for in general if you have risk factors, and a symptom, such as a lingering cough in a longtime smoker for lung cancer.

So why don't we just bite the bullet and get everyone full-body MRIs? Well, because they often come up with "red herring" findings. Like, a solitary cyst in your kidney, or in your liver, or a small kidney. Or a lipoma (benign fatty growth) that you didn't realize was there already for years. And these cause people needless worry because they won't do anything and they don't mean anything, but for the rest of your life you're worried about an essential meaningless finding, and we'd do followup studies to show again that it really is a meaningless finding. This is why we do age-appropriate screening for specific cancers, or when you have a symptom.

And the ugly truth? Knowing all the above, we could still go ahead and order a full-body scan for you, but your insurance company actuaries have seen the studies, know that it's not "needed", and would make you foot the bill...

Vy Chu, MD