PET Scan IDs Breast Cancer Spread
Before Surgery, Technique Points to Cancerous Lymph Nodes
Aug. 21, 2006 -- Before surgery, a PET-scan technique can detect the spread of breast cancerbreast cancer to a woman's lymph nodes, Cedars-Sinai researchers find.
When breast cancercancer spreads to the lymph nodes, those lymph nodes must be removed. By pointing doctors directly to cancerous lymph nodes, the new technique could help some women avoid a second surgery.
The technique involves injecting a woman with a glucose-like radioactive tracer called FDG for imaging. Cancer cells grow very fast, and need more food -- glucose -- than normal cells. So they gobble up more FDG than other cells, and thus shine more brightly on PET (positron emission tomography) imaging scans.
But Alice Chung, MD, Edward H. Phillips, MD, and colleagues did not visually examine FDG-PET scans taken of 51 women with invasive breast cancer. Instead, they calculated how much FDG their lymph nodes absorbed -- a value called the standardized uptake value or SUV.
Over a certain SUV threshold, positive PET scans were 100% accurate in predicting cancer in the lymph nodes. However, it was only 60% sensitive. This means that it missed some cancerous lymph nodes.
"FDG-PET is not a perfect test," Phillips said, in a news release. "As we continue to see advances in technologies, I believe we will be able to identify smaller and smaller tumors with greater accuracy."
The researchers say they don't think FDG-PET scans should replace other techniques, such as sentinel-node biopsy, that help doctors determine whether a woman should undergo lymph node removal. But they say the technique puts another arrow in the quiver of surgeons working to make breast cancer treatment more effective and easier on patients.
Chung and colleagues report their findings in the August issue of Archives of Surgery.