Marrow culture aids in cancer prediction.

Marrow culture aids in cancer prediction

Surgeons have no sure means of knowing whether some cancer cells from a breast tumor they have removed may already have spread to a distant site. So, in deciding whether to embark on a course of postsurgical chemotherapy, they must rely upon indirect clues to judge the chances of recurrence, including cancer severity and the presence or absence of estrogen receptors on the tumor cells.

Now researchers say they've developed the first direct test for detecting cancer cells that have spread to bone marrow. Their technique, if validated in further studies, should help identify women at low risk of recurrence and may save some women from unpleasant chemotherapy regimens.

William P. Vaughan, J. Graham Sharp and their colleagues at the University of Nebraska Medical Center in Omaha cultured bone marrow cells taken from 28 women with breast cancer. The women were candidates for an experimental breast cancer therapy involving intensive, whole-body radiation treatments that wipe out hidden cancer cells. Since the treatment also kills marrow cells, surgeons first remove some marrow, then reinfuse it after radiation therapy ends -- a procedure, called autologous marrow transplantation. Using special stains, they scrutinize the extracted marrow for cancer cells. If any appear, the doctor may "purge" the malignant cells with drugs before reinfusing the patient.

The Nebraska researchers plated marrow cells in a culture medium. Within a few weeks they saw cancerous growths in more than half of the specimens that had appeared normal under conventional staining techniques. In follow-up periods ranging from six to 38 months, eight of the 16 culture-positive women suffered relapses. In contrast, only one with a negative culture relapsed, the team reported last week at the annual meeting of the American Society of Clinical Oncology in Washington, D.C.

"It's a very important observation," says oncologist Bruce D. Cheson of the National Cancer Institute in Bethesda, Md. Autologous marrow transplants among breast cancer patients are "going gangbusters," he says, with hundreds performed per year despite a relative shortage of data regarding the technique's ultimate benefits. Physicians would value any test that helps predict cancer outcomes and treatment requirements, Cheson says.

"this is the first technique for actual detection of small numbers of malignant cells at a distant site," Vaughan says. He estimates that the method can detect a single cancer cell in a sample of 10,000 cells -- far better than a pathologist could do looking at a stained slide under a microscope.