The Peter MacCallum Cancer Centre in Melbourne has for the last six-years been conducting a study into the use of positron emission tomography (PET) scans to better predict the success of therapies.
Professor Miles Prince from the Cancer Centre expects the study to change the way breast cancers are treated worldwide as the scans are used to monitor breast cancer patients in order to establish if treatments are successful.
Professor Prince says the scans give an indication of long-term outcomes and if the patient's health is not improving doctors are able to change to alternative treatments far earlier than was previously possible.
PET scans differ from conventional computed tomography (CT) scans because they show the functions of the cells whereas CT scans show the structure of the body.
Professor Rod Hicks, chairman of molecular imaging at the centre, said the use of PET scans to monitor whether treatments were successful was a breakthrough.
With PET scans it is known within weeks if the treatments are working, whereas conventional scans can take months to deliver their verdict on a treatment; time when patients might unnecessarily accumulate the toxicity of the drug or treatment.
The six-year trial of the new technique involved 47 women with aggressive breast cancer.
"In each variable commonly associated with a higher risk for developing breast cancer − age older than 65, age at menopause, a body mass index greater than 25, higher estradiol levels, prior use of estrogen replacement and a family history of breast cancer − use of raloxifene reduced incidence of breast cancer when compared to a placebo drug," Dr. Lippman said. "But it also reduced incidence in each of those variables that should have lowered risk, such as younger age, later menopause, etc., compared to use of a placebo drug."
"We don't define the lowest limit of risk, the point at which toxicity associated with use of raloxifene outweighs the benefits," he said.
Dr. Lippman stressed that he cannot comment on how raloxifene in this study measures up to tamoxifen use in general. He explains that although these findings come on the heels of the June publication of the 19,747-participant STAR trial, which evaluated tamoxifen against raloxifene in reducing breast cancer risk, no comparison can be made between the MORE, CORE and STAR clinical trials.
"These studies looked at two different groups of women," Dr. Lippman said. "Women enrolled in STAR were at high risk for developing breast cancer, so presumably, they had higher levels of estrogen in general. Women who participated in MORE and CORE were older and had osteoporoses and it is assumed that these women generally have lower levels of estrogen, because that is a risk factor for development of the disorder."
Raloxifene, also known by the trade name Evista, has not been approved by the federal Food and Drug Administration as an agent to prevent breast cancer development.
Co-authors of the study include investigators from the University of Pittsburgh, the Angeles Clinic and Research Institute, California Pacific Medical Center Research Institute, and Eli Lilly & Company, which manufactures raloxifene.
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