For decades, women with breast cancer have struggled with a decision — whether or not to undergo chemotherapy. Researchers have long suspected that some people are predestined to respond well to chemotherapy and others to respond poorly or not all. The problem is that it has been impossible to tell which was which, without going through with the treatment.
Now, a new test that measures two types of protein — one of which appears to encourage cancer growth and the other which acts as a tumor suppressor — can help identify which breast cancer patients will benefit from chemotherapy and who will not.
Known as OncoPlan-A, the test is already commercially available. Studies have shown that it can predict the aggressiveness of the patient's tumor and the relative risk of disease recurrence following surgery in breast, colon and gastric cancers.
This latest study focused whether or not this test could be used to predict how individuals with breast cancer would respond to chemotherapy.
According to A. Raymond Frackelton, Jr., Ph.D., a Brown University associate professor, staff scientist at Roger Williams Medical Center and Vice President of Research at Catalyst Oncology, which is marketing OncoPlan, "patients whose tumor cells are low in one protein might respond better to chemotherapy. To test this idea, the researchers looked at proteins in tumors from 2,380 women from British Columbia who were diagnosed with invasive breast cancer, 717 of whom received chemotherapy.
They found that people with low levels of a protein called p66 Shc and who did not receive chemotherapy had very poor outcomes. If they did receive chemotherapy, however, their chances of relapsing and dying from their disease were reduced by two-fold or more, said Frackelton. Conversely, women with high levels of p66 Shc had a much higher likelihood of surviving their disease but appeared to derive no benefit from chemotherapy, he said.
Study results were presented at the September 2006 meeting on Molecular Diagnostics in Cancer Therapeutic Development organized by the American Association for Cancer Research.