DC Medical Malpractice & Patient Safety Blog

The political brouhaha that followed the new guidelines on mammograms has now died down, maybe enough so that patients can start to absorb the quiet truth about breast cancer and the role of mammogram screening.

The National Breast Cancer Coalition has worked since 1991 to get Congress to fund research and appropriate treatment for this disease. The Coalition believes in sticking to the facts and analyzing closely the research studies that have been published about what mammograms can and cannot do for women who aren't aware of a lump in their breasts.

Here is an excerpt from their discussion of the US Preventive Services Task Force recommendations:

Has breast cancer screening had a significant impact on mortality from breast cancer?

No, over 40,000 women continue to die of breast cancer each year, despite the emphasis on breast cancer screening in our country. To change this, we must address the facts about breast cancer and not simply accept what we want to believe. The fact is that all breast cancers are not equal and that we don’t currently have tools for “early detection” that are good enough for the life-threatening breast cancers.

But doesn’t early detection save lives?

Not necessarily. Some breast cancers are slow-growing and have a good prognosis, whenever they are found, whether small or large. Other breast cancers are aggressive and fast growing, and we don’t have the tools to catch them early enough or treatments that will work.

Why doesn’t mammography work as well for women in their 40s?

Younger women have more dense breast tissue, making mammography less accurate. Also, mammography is better at detecting slower growing tumors more common in older women, than the fast-growing, aggressive tumors more often found in younger women. And the balance of benefit vs. harm changes as women get older since the likelihood of breast cancer increases with age. The disease is relatively rare in younger women.

But shouldn’t a woman in her 40s have a mammogram if she feels a lump?

Certainly. The Task Force recommendations are meant to be guidelines for broad public health policy for healthy women with no symptoms, and an average risk for breast cancer. These guidelines are not meant for any woman with an increased risk or for any woman who feels a lump or change in her breast. Women who have any concerns need to visit their doctors and may need diagnostic mammograms. Mammograms taken to assess a problem are not the kind of mammograms we are talking about with these guidelines.

What’s the harm in trying to detect breast cancer early, even if our methods don’t work that well?

The harms from screening too early or too often include increased false positives, leading to increased imaging and radiation exposure, biopsies and scarring that can affect the accuracy of future mammograms, and anxiety. There is also the harm of overdiagnosis of breast cancer. This would involve treatment of cancers that would never be life threatening, and treatment of cancers that may regress, or go away on their own. The treatments for breast cancer are not aspirin, they are toxic and can be life threatening; the scenario of overdiagnosis should not be taken lightly.

The cancer coalition supports the Task Force's recommendation that women who are not in a high risk category (from a family history or presence of the BRCA gene) start thinking about mammograms around age 50, not age 40.

Here is another useful summary from the National Breast Cancer Coalition: 31 Myths and Truths about breast cancer. You can read it here.

We have discussed the statistics behind breast cancer screening in several entries on this blog. Read them here and here and here. My belief is that women need to understand the numbers and then make a personal choice. Politicians don't need to enshrine mammograms as some sort of constitutional right, as happened in the US Senate not long ago. We need more compelling evidence before this screening device goes onto the "do not touch" pedestal.

A drug that can cut a woman's risk of breast cancer in half when taken regularly is proving to be a tough sell when women have a chance to fully understand the pros and cons of the medication.

The drug is tamoxifen. For women at high risk of breast cancer (who have a gene associated with it or a close relative with breast cancer), tamoxifen can reduce the odds of developing breast cancer by 50 percent. Yet recent studies show that when the statistics are laid out for women to make an informed choice, only one in 100 actually fill the prescription.

Are the women who decline to take tamoxifen being illogical? Or just making their own personal choices about what is important to them?

Tamoxifen interferes with the body's use of estrogen. That can lower the risk of estrogen-dependent breast cancers but can increase the risk of other estrogen-related side effects like cancer of the endometrium (the lining of the uterus), blood clots and sexual dysfunction.

Here is how the numbers were spelled out to women in a recent study at the University of Michigan, as reported by Tara Parker Pope in the New York Times:

The risks of breast cancer vary with age, family history, and age of first childbirth. So a 52-year-old woman who had her first baby after age 30 and whose mother had breast cancer, has about a 1.9% risk of developing breast cancer over the next five years. If 1,000 women just like this 52-year-old took tamoxifen over those five years, the research says that here is what would happen:

* Of the nineteen women (same as 1.9%) who otherwise would have developed breast cancer, nine will not develop breast cancer. (Thus the statistic about lowering the odds by half.)

* Thirteen women would avoid broken bones from osteoporosis, another benefit of tamoxifen.

* Twenty-one women would develop endometrial cancer (typically more treatable and less deadly than breast cancer if caught early).

* Twenty-one women would develop blood clots.

* Thirty-one women would develop cataracts.

* Twelve women would experience sexual problems.

* One hundred twenty extra women would get hot flashes and other menopausal symptoms (in addition to those who would get such symptoms anyway).

Behavioral economists might say this is an example of "omission bias," where we are more worried about a small risk from doing something new (taking a pill) than we worry about a larger risk from doing nothing. Put another way, we often see the status quo of doing nothing as safer when it really isn't.

At least that's how the researchers quoted in the NYT article explained the unpopularity of tamoxifen. But for readers who posted comments on the newspaper's blog, they tended to see the women voting against tamoxifen as being quite sensible. It just doesn't sound worth the downside.

Part of the problem is the apples-to-oranges comparisons involved when a fatal condition is compared to a non-fatal one. As one commenter posted:

What might make women make better choices is if they had data on whether the pill reduced the risk of DEATH from all causes. If only some of the breast cancers avoided would have resulted in death but all of the endometrial cancers aquired resulted in death, women might make the choice to avoid tamoxifen. If the risks were reversed, they might choose to take tamoxifen. We have to move beyond a discussion of risk of cancer and towards a discussion of risk of cancer DEATH. http://www.medpie.com — Barbara Lock, MD

If we had the same careful discussion about mammograms, women likely would opt for far fewer of these tests, which save lives on a similar scale as tamoxifen, with plenty of downside.

My conclusions from this debate:

* Patients need to know there are no magic bullet drugs that are all gain, no pain. Tamoxifen interferes with estrogen, which is good for some diseases, not so good for others. This is typical. Each drug must be carefully weighed for its pros and cons.

* We're all better off with a full exploration of the odds and then make our own decisions. There is no right or wrong.

* The best way to understand risk is the way it's spelled out here: with numbers of actual people in a given standard-sized group. It's too confusing when we talk about percent this and percent that.

I tell readers how to do this technique of "counting the people" in my book: The Life You Save: Nine Steps to Finding the Best Medical Care -- and Avoiding the Worst.