Cancer and optimism bias

Read a really interesting piece about stage IV cancer in the Times earlier this week.  Basic gist: (sadly) a huge number of patients really don’t appreciate how bad or how incurable their cancer is.  Very much hit home with my mom’s stage IV diagnosis over 3 years ago.  The essay is specifically about a study of lung and colon cancers, but I’m sure much of it applied to these advanced cancers more broadly:

 Most patients with these so-called stage 4 cancers who choose to undergo chemotherapy seem to believe, incorrectly, that the drugs could render them cancer-free.

That is the finding of a recent national study of nearly 1,200 patients with advanced cancers of the lung or colon. Overall, 69 percent of those with stage 4 lung cancer and 81 percent of those with stage 4 colon cancer failed to understand “that chemotherapy was not at all likely to cure their cancer,” Dr. Jane C. Weeks, an oncology researcher at the Dana-Farber Cancer Institute in Boston, and colleagues reported in The New England Journal of Medicine.

When patients do not understand the limitations of such treatment, their consent to undergo it is not truly informed, the authors concluded.

This is not to say that chemotherapy is pointless when cancer is far advanced. Various drugs, some with limited toxicity, can be used as palliatives, perhaps shrinking tumors temporarily to relieve symptoms, slowing the cancer’s growth and prolonging the lives of some patients.

But aggressive chemotherapy when death is but weeks or months in the offing can seriously compromise the quality of patients’ remaining time and may delay their preparations for the end of life, to the detriment of both patients and their families.

“If you think chemotherapy will cure you, you’re less open to end-of-life discussions,” Dr. Weeks said in an interview.

Yep, yep, yep.  And definitely part of the problem is oncologists who just want to treat, treat, treat.  Now, in my mom’s case the chemo really helped in some ways as the cancer had spread to her spine and was causing great pain, but it certainly seemed to me that she had a way over-optimistic sense of being “cured.”  Now, in truth, my mom was easily among the most optimistic people I’ve ever known (definitely to a flaw), but I also feel like the medical professionals could have certainly done a better job here.

Anyway, just a couple of days later, there was a very interesting piece about the huge overdiagnosis of breast cancer.  The latest study is just strong confirmation, but the basic point that breast cancer screening leads to many, many diagnoses that actually do nothing to save women’s lives.  Ironically, my mom was well aware of the futility of breast cancer screening which led her to be skeptical of the annual pap smear which probably would have saved her life.  Anyway, on the breast cancer issue:

After correcting for underlying trends and the use of hormone replacement therapy, we found that the introduction of screening has been associated with about 1.5 million additional women receiving a diagnosis of early stage breast cancer.

That would be a good thing if it meant that 1.5 million fewer women had gotten a diagnosis of late-stage breast cancer. Then we could say that screening had advanced the time of diagnosis and provided the opportunity of reduced mortality for 1.5 million women.

But instead, we found that there were only around 0.1 million fewer women with a diagnosis of late-stage breast cancer. This discrepancy means there was a lot of overdiagnosis: more than a million women who were told they had early stage cancer — most of whom underwent surgery, chemotherapy or radiation — for a “cancer” that was never going to make them sick. Although it’s impossible to know which women these are, that’s some pretty serious harm.

But even more damaging is what these data suggest about the benefit of screening. If it does not advance the time of diagnosis of late-stage cancer, it won’t reduce mortality. In fact, we found no change in the number of women with life-threatening metastatic breast cancer.

Wow.  That’s a lot of needlessly diagnosed breast cancer and a lot of harm.  What do to differently?

What should be done? First and foremost, tell the truth: woman really do have a choice. While no one can dismiss the possibility that screening may help a tiny number of women, there’s no doubt that it leads many, many more to be treated for breast cancer unnecessarily. Women have to decide for themselves about the benefit and harms.

But health care providers can also do better. They can look less hard for tiny cancers and precancers and put more effort into differentiating between consequential and inconsequential cancers. We must redesign screening protocols to reduce overdiagnosis or stop population-wide screening completely. Screening could be targeted instead to those at the highest risk of dying from breast cancer — women with strong family histories or genetic predispositions to the disease. These are the women who are most likely to benefit and least likely to be overdiagnosed.

The more we learn, the more it seems that breast cancer resembles the over-diagnosed and over-treated prostate cancer (though, clearly, it is on average a much more serious disease).  Clearly, our medical system needs to do much better.  And it can, if we get smarter about it.

About Steve Greene
Professor of Political Science at NC State

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