St. Louis, June 11, 2001New research shows that PET scans can often identify which women with advanced breast cancer are likely to respond to hormone therapies such as tamoxifen.
Using PET scans, we were able to predict within two weeks who was responding to hormone therapy, said Joanne Mortimer, M.D., professor of medicine at Washington University School of Medicine. That is very significant. If doctors could tell within two weeks that someone will respond to hormone therapy, they will be less likely to prescribe chemotherapy for those patients.
The study, led by Mortimer, of the Siteman Cancer Center at Washington University and Barnes-Jewish Hospital, is published in the June 1 issue of the Journal of Clinical Oncology. Hormone therapy is kinder and gentler to patients than chemotherapy, and is usually just as effective. But according to Mortimer it is greatly under-used by physicians. Often, this is because the therapy initially produces symptoms of tumor growth, so doctors cant tell whether a woman is responding normally to the treatment or whether her cancer is progressing.
The problem occurs because hormone therapy stimulates breast tumors to flare up and grow a bit before causing them to shrink. This can result in pain at tumor sites and in elevated tumor markers in the blood. This flare reaction is physically experienced by about one in 20 women with advanced breast cancer who receive hormone therapy. At the same time, it is also known that women who experience a clinically detectable flare reaction respond to hormone therapy.
We proposed that all patients who eventually respond to hormone therapy have a temporary flare reaction, but that it occurs subclinically in most cases, said Mortimer. The researchers further proposed that this subclinical flare could be detected using positron emission tomography (PET). PET measures the functional activity of normal and diseased tissues in the body.