Tailored Treatment

Study Probes Which Breast Cancer Patients Need Chemotherapy

Most postmenopausal women with small breast tumors don’t need chemotherapy to reduce their recurrence risk after lumpectomy.

To try to determine who does, a test that measures a tumor’s aggressiveness based on its DNA will be tested nationally in more than 10,000 of these women.

“Because they have such small tumors, it’s hard to tell who needs chemotherapy,” said Dr. Thomas A. Samuel, an MCG hematologist/oncologist specializing in breast cancer and a study principal investigator.

Of every 100 postmenopausal women with a small tumor that has estrogen receptors and no sign the disease has spread to the lymph nodes, about 12 to 15 need chemotherapy to reduce the risk of recurrence, Dr. Samuel said.

But because no definitive test indicates who needs it, all receive chemotherapy, even though the vast majority would do well with lumpectomy, radiation and hormone therapy that keeps cells from being refueled by estrogen.

Chemotherapy’s potential side effects— including hair loss, nausea, vomiting and increased risk of leukemia and heart problems—are onerous enough to cause some women to discontinue treatment. “I know that a number of these patients probably don’t need it, but there is no way for me to know who they are ahead of time,” Dr. Samuel said. “I think this trial will help us find who should get it and who should not.”

The commercially available test he is studying—the Oncotype DX™— determines the likelihood that cancer will spread or grow by analyzing 16 tumor genes and five reference genes as controls. “How cancers behave largely depends on what the DNA is like,” Dr. Samuel said.

The test has been on the market more than a year but is expensive and not widely used. Dr. Samuel used it only twice before the study but predicts it will become a standard part of treatment if the federally funded study supports current findings.

 

The Trial Assigning Individualized Options for Treatment, or TAILORx trial, coordinated by the Eastern Oncology Group, is the first study resulting from the National Cancer Institute’s Program for the Assessment of Clinical Cancer Tests.

Enrollees with the lowest recurrence scores will have radiation therapy and hormonal treatment following lumpectomy. Those with the highest will also get chemotherapy. “The debate is in the intermediate risk group. That is where most women fall and the ones where we are not sure what to do,” Dr. Samuel said. Most will be randomized to either get chemotherapy or not.

Dr. Samuel hopes to enroll about two patients per month; the trial likely will be open several years depending on how long it takes to enroll 10,000 women nationally. Participants will be followed for at least five years.

Toni Baker

 

 

 

The Medical College of Georgia is the state’s health sciences university with a tripartite mission of education, research and patient care.