Breaking the breast cancer code

Genetic mapping holds promise of targeted, and more successful, treatment

September 26, 2012|Susan Reimer

How many children have you had, and did you wait until after 30 to have the first one? Do you have more than one drink a day? Did you get your period before you were 12? Do you exercise? Have a low-fat, high-fiber diet? Did you breast-feed?

Do you work nights, wear a bra, have breast implants, use the Pill or wear antiperspirant? Do you smoke?

Did your mother, your aunts or your sisters have breast cancer? Do you have the breast cancer gene? Do you want to know if you have the breast cancer gene? Would you consider a pre-emptive double mastectomy if you did have the gene?

There is no good kind of cancer, of course, but breast cancer is its own brand of torment for women, and not just because of the role of the breast in shaping how we see ourselves or how we define our womanhood.

Did we bring this on ourselves with lifestyle choices we didn't know mattered when we made them? Or are we the unwitting inheritors of scrambled genetics for which our own mothers might be to blame?

The treatment for this disease can be almost Medieval. Slash, burn, poison.

And the advice from doctors can be all over the map. Have a mammogram every year; don't have mammograms until after 40. Just have a lumpectomy. Have a full mastectomy. Shrink the tumor first, and then have surgery. Have radiation after the chemotherapy. You decide.

And every fall — just in time for October and breast cancer awareness month, it seems — there is an announcement of some new, ground-breaking research. But it always comes with the caveat that it will be years until patients might benefit.

It has happened again. This time, the Cancer Genome Atlas — a massive, federally funded effort to map the genetics of cancerous tumors — has filled in some blanks on four kinds of breast cancer, and the hope is that future treatments can be more refined and targeted — and successful.

"This study is looking at sub-types of breast cancer that have already been reported," said Dr. Kathy Helzlsouer. She is director of the Prevention and Research Center at Mercy Medical Center and a pioneer in breast cancer research. "That is not new. That is already in the literature.

"What the study has done is better characterize those sub-types by looking at specific genetic changes. The most important aspect is that this information could be used to better direct treatment."

The study, published in the scientific journal Nature this week, identified the genome sequence of the tumors in 825 women. This is part of an effort to sequence the genes in the 20 most common cancers — instead of identifying a cancer by its location in the body, the goal is to identify it based on its genetic coding.

The Cancer Genome Atlas, which has already improved the genetic information base on lung and colon cancers, saw that not all breast cancers are the same. It identified 40 genetic changes that might be targeted by drugs — many of them already available and used to treat cancers with similar mutations.

One type of breast cancer, for example, more closely resembles ovarian cancer. Why not use ovarian cancer drug treatments already available instead of wasting time using conventional breast cancer regimens? "Not every breast cancer is the same, and not everyone responds the same way," said Dr. Helzlsouer.

"Breast cancer treatments often don't work for a particular patient, or they work and then they stop working and you go on to try another one," she said.

"And some of these treatments can be devastating. Why would you go through them if they won't help you?"

In addition, some cancer drugs are expensive, and they can damage other vital organs or trigger another form of cancer, such as leukemia. It makes sense to know exactly which patients will benefit from their use.

The genetic mapping of a particular cancer may reveal its cause, which is important, of course. But more immediately — and more important to a patient who already has the cancer — genetic mapping can show doctors how to switch the cancer cells "off," to stop them from replicating, or how to cut off their blood supply and starve them to death.

"This is a process," said Dr. Helzlsouer. "It is one thing to show that certain kinds of cancer have this particular genetic change. It is another thing to keep it from growing. Cancer cells are smart."

Indeed. Breast cancer has held women hostage all these years, with its determination to survive whatever we use against it. We have a clearer picture of this cancer now, perhaps, but there remain years of drug trials and clinical trials before we know if we have also found the way to defeat it.

Susan Reimer's column appears Mondays and Thursdays. She can be reached at and @Susan Reimer on Twitter.

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