Sister vs. sister

I think this Times article by bioethicist Robert Klitzman is chilling:

"I pleaded with my sister, Susan, to get genetic testing, but she refused," a woman recently told me in my office.
Susan, the woman said, already had breast cancer, so her health insurance company would have paid for the testing.
"I am at high risk for developing breast cancer," she said. If she knew that Susan was gene positive, she would consider having her own breasts removed.
The woman in my office couldn't afford the genetic testing herself: it costs over $3,000. Her insurance wouldn't pay for the testing because she had not yet had cancer. Yet she had had multiple calcifications in her breasts. Tumors could be hiding there, undetected. The woman's mother and aunt had died of the disease.
...
Susan's refusal to be tested affected this woman's life, as well. In the new genetic age, the notion that family members are "bound by ties of blood" takes on new meaning.

Of course, doctors already routinely test people for infectious disease, and often are required by law to notify others who have been exposed, as for STDs. Should genetic testing become like this?

Here's one reason why not: if a woman is seriously thinking about prophylactic mastectomies, then wouldn't the test be a lot cheaper than that?

The problem in this case is that not all hereditary breast cancer alleles are yet known, and so they cannot be tested. Another problem is that some insurance companies will pay for prophylactic mastectomy for women with a strong family history of breast cancer but won't pay for testing.

And some women simply prefer to have the surgery without knowing whether they have the allele. I found this article about "Considering Prophylactic Breast Surgery", which describes one woman's decision process:

Genetics counseling and testing may be performed prior to prophylactic breast surgery. Pat opted not to receive genetics counseling or testing, however, she says, "My insurance would cover it if I chose to. I think I was afraid of what I might find out so I decided not to participate in either." Some insurance companies may require it before actual surgery.

It seems to me that the issue doesn't really revolve around testing, but instead around the difficulty of the decision to get preventative surgery. And it certainly is a difficult decision. Consider this discussion from the New England Journal of Medicine, which accompanied a 1999 study showing the efficacy of the procedure:

In the end, however, what the study illustrates most dramatically is the cost of prophylactic mastectomy. Even in the face of an unprecedented 90 percent reduction in the incidence of breast cancer and of death from breast cancer, the fact remains that this is a study of 639 women who, because of the fear of breast cancer, underwent a disfiguring and potentially psychologically damaging operation. As a result, instead of the 20 deaths related to breast cancer that were expected during the period of observation, there were only 2. The saving of those 18 lives is clearly important, but the 621 women who probably would have survived without prophylactic mastectomy paid a price that will be considered unacceptable in the future.

Like many other real-life risks, the risk of cancer is low but catastrophic, while the cost of reducing the risk is high. The test could help resolve how high the risk actually is --- if the test actually could detect all the alleles that cause breast cancer. But it doesn't.

Therein lies the point of testing the sister. If the sister who had cancer also carries one of the tested alleles, then finding a negative result in the unaffected sister is very informative about her risk of cancer. If the affected sister doesn't have a tested allele, then there is no point in testing the unaffected sister; the test just won't tell what her risk might be.

And that's exactly what happened:

In the end, Susan finally did get testing, and her tests were negative. Perhaps she had a gene that has not yet been identified.
In any case, Susan's sister still faces difficult choices, and she is trying to decide whether to undergo prophylactic radical mastectomies.

I wonder how many other conditions will come to be like this --- it not only matters what alleles you have, but whether you share alleles with relatives that suffer from some disease. How much will we be testing individuals, and how much their genetic backgrounds -- by way of the phenotypes of their family members?