Rethinking Breast Cancer

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--Doctors are experimenting with new ways to deliver lethal radiation that more closely targets the tumor and takes just a few days at most--compared with the more usual six-week regimen--to finish the job.

--Researchers who are trying to minimize the need for chemotherapy are finding that patients can avoid chemo altogether if just one or two cancer cells are discovered in a lymph node--apparently these cells are not active enough to cause any further trouble.

Most of these new approaches still need to be more fully tested before they can be widely adopted. Some of them will undoubtedly fail. The ultimate prize, which could be available within the next 10 to 15 years, would be a diagnostic test that determines which genes in a particular tumor have gone awry. As doctors are increasingly aware, it's not just a tumor's size but its underlying biology that determines how quickly it will grow. Genetic tests may one day accurately identify those tumors that are likely to spread and those that are not. The tests may also tell doctors to which drugs your particular tumor is most vulnerable.

Before peering any further into the future, however, it helps to know a little biology. Most breast cancers begin in the milk ducts, narrow passageways that radiate throughout the breast. A few cells, for reasons that are not completely understood, start accumulating genetic mistakes that cause them to grow abnormally. Eventually the cells develop into DCIS. The good thing about dcis cells is that they haven't spread beyond the milk duct. The bad thing is that they are malignant. "Some people call DCIS precancer, but it's not precancer," says Dr. Dennis Slamon, director of breast-cancer research at the UCLA School of Medicine. "It's preinvasive. It's cancer that hasn't invaded outside the breast ducts."

After a tumor starts to break out of its milk duct, it's often still quite small. About the smallest tumor a mammogram can pick up is 0.5 cm to 1 cm (0.2 in. to 0.4 in.) in diameter. By contrast, the average cancers that are felt either by women or their physicians are around 2.5 cm, or about an inch. Even though mammograms still miss about 10% of all tumors, it's their ability to spot smaller tumors, which are generally easier to treat, that keeps women coming back for their annual appointment.

Once the cancer puts down roots in the lymph nodes, the prognosis gets worse. The lymph nodes act as a kind of sewer system for many types of toxins and wastes. Tumors growing in the lymph nodes have a greater chance of breaking off and traveling to the bones, brain, lungs or other parts of the body, where they can seed new growths, called metastases. Here again, doctors used to think that any breast cancer that had spread to the lymph nodes must have been growing a long time. Now they realize that the fact the cancer has shown up in the lymph nodes may have more to do with how aggressive it was from the start than with how long it has been growing.