Monday, February 20, 2012

Myth of early detection

The conviction that early detection of cancer saves lives is buried deep in our bones. Nearly everyone believes that advanced imaging tests like CT, MRI, and PET provide cancer patients with clear, unquestionable benefits. We don’t need our physicians to convince us of this since most of us know someone who was “saved” by a timely scan or screening exam. In our tech-addled culture, in which we place blind faith in technologies we can’t begin to understand, how could it be otherwise?

Yet early detection is seriously overrated. It may be counterintuitive, but most early detection exams do not strongly affect whether you live or die. Not the PSA for prostate cancer, not early detection of lung or testicular or pancreatic cancer, or glioblastoma, a common type of brain cancer. Colonoscopy might cut mortality, but this has never been tested in a randomized, controlled trial. The Pap test for cervical cancer and the fecal occult blood test for colorectal cancer are about the only screening tests shown to decrease mortality from the disease they target. Even mammography is mired in controversy.

Logic suggests that finding a tumor when it is small should mean a better chance that surgery, radiation and/or chemo- or immunotherapy will eradicate it, allowing you to live until something else kills you. Unfortunately, the science doesn’t support this convenient assumption. There may, in fact, be good reasons to have the scan or test anyway, but the trust we place in them to save our lives is largely misplaced. The evidence just isn’t there.
Why are these men smiling?

Ironically, it’s in this context that I’ve scheduled a PET/CT scan for early next month. It’s been a year since my last exam and while I have no clinical symptoms that suggest my metastatic melanoma has advanced, I’m taking the precaution of having the scan anyway. I’m not happy about it. I would hope to be proved wrong about this, but even if findings show the cancer has metastasized to internal organs, I don’t expect to live longer for knowing this. Just because my doctor has suggested I have the test and my insurance covers the cost doesn’t mean it’s a slam-dunk decision. I’ve already dithered over this decision for months.
I should clarify: Because I have a high-deductible policy, I will pay at least $2200 out of pocket for the scan. Even after my deductible is satisfied sometime later this year, I’m obligated to pay half the cost of all advanced imaging exams. The folks at Blue Cross/Blue Shield have also read the literature and reached the conclusion that many types of scans are overutilized. They discourage the use of PET/CT by making it financially painful to the patient for having a scan. Their parsimony may be justified on this occasion at least.
This is emotionally delicate territory. I’ve had five PET/CT scans since being diagnosed with melanoma. All of them resulted in ambiguous findings, albeit nothing that turned out to be life-threatening. The run-up to the scans and the time waiting for results immediately afterwards is excruciating, as I’ve written about many times before. Were I to have positive findings this time, I’m not sure the emotional wallop could be much worse than the waiting for negative results. I’ve so far spent about $10,000 for radiologists to tell me essentially nothing about my cancer.
One reason early detection—or in my case earlier detection—doesn’t make a bigger difference is that, absent effective therapy, it hardly matters when mets are found: early or late, you’re doomed. There are, for example, major cancer centers in the U.S. that do not typically scan stage IV melanoma patients who are asymptomatic. Among them is M.D. Anderson in Houston—the top-rated cancer center in the country. It didn’t adopt this policy because it’s trying to save money for the insurance companies. In their experience, they simply haven’t found any survival benefit for regular scanning. Metastatic melanomas tend to be rip-snorters and likely to kill you in short order, but some are indolent, as mine is, and they just hang around interminably. Either way, drug therapies are mostly ineffectual and finding melanoma earlier doesn’t change its natural progression.
If you look for cancer of any type in asymptomatic people, as screening does, you are more likely to find indolent forms of it for the simple reason that they, by definition, spend more time in a nonthreatening form. This has proved to be especially true in prostate cancer, where tumors are picked up regularly that don't need to be treated aggressively, if at all, but usually are. Failing to detect an indolent cancer early doesn’t necessarily put you at much of a disadvantage. In a manner of speaking, metastatic cancer is going to do what it’s going to do when it wants to do it.
The medical-industrial complex to which cancer patients submit themselves is hugely biased toward taking action. So are we as patients. That includes me, as brave as I might try to sound. Cancer is a fearsome disease and most of us want a technological solution to our dilemma, regardless of whether or not there is statistical evidence that it does any good. We want to believe it can save us, our doctors want it to save us, even though they may have private doubts, and the companies that make and market the machines, and in some cases provide the scans, want us to believe they work miracles. There is an extraordinary momentum toward just getting on with it.
And so I will once again be the dutiful patient and have my scan. If something nasty turns up, I will then in consultation with my oncologists make some tough decisions. If nothing is found that’s actionable, then I’ll feel elated again and relieved for having put myself through the emotional blender. Beneath it all, I feel I’m being played but am powerless to stop it. Research that either verifies or refutes the value of early/earlier detection can’t come soon enough.


Steve said...

So, can I cancel my digital prostate exam skedded for Friday? I hope so--

Peter Ogle said...

We can laugh (or cringe) about this exam, but at least it's hands-on medicine. If your prostate is enlarged, the doc will feel it. That strikes me as real medicine that can't be argued against. I'd happily trade one scan for an annual physical any day.

AnnieVan said...

This is probably old news....but here is a story about a study published today in NEJM about Vemurafenib

Lars said...

After having 3 melanoma in situ's I have anxiety every time I see me Derm. Sometimes, I wonder why do even go but I guess medical science and my "gut" tells me that early detection is still the way to go.

Also, patiently waiting the results of 2 more biopsies.

Eric Skinner said...

Hi Peter. I feel your pain. I have another scan in about two weeks, not long after I have arthroscopic surgery on my left knee (somehow I managed to get a severely torn interior meniscus). My last Chromagranin marker test three weeks ago revealed a level of 98 (normal is zero to fifty). Back in September it was 95. Dr. Pommier feels much more upbeat than I do, perhaps because he has not had cancer. I plod ahead because I have no other choice. My diet is still limited and probably always will be. My personal life outside of cancer is better than it has been in decades. Yet I still search for meaning in all this. We should get together sometime soon.

Eric S.