When the scanning procedure was used to measure the accumulation of radioactive glucose fluorodeoxyglucose (FDG) in tumour tissue from patients with locally-advanced breast cancer before and after preoperative chemotherapy Researchers in Australia have shown: Women who had the highest accumulation at the beginning and who then had the highest percentage drop in accumulation after four cycles of chemotherapy were more likely to have a complete response to their treatment - this means no tumour cells remaining in the final tumour resection specimen. However, measurements taken using mammography or ultrasound were not able to predict a pathological response accurately.

FDG-PET works by injecting a sugar molecule, tagged with a radioactive tracer, into the patient. The molecule is metabolically active and concentrates in tumour tissues where it emits energy that PET scanning can detect. PET measures the “standard uptake values” (SUVs)- in other words, how much FDG has accumulated in the tumour. If the SUVs drop after chemotherapy, this shows that there are fewer, or no cancer cells available where the FDG can accumulate.

This study suggests that tumours with high initial SUVs seem to be more sensitive to chemotherapy, thereby giving a better chance of achieving a reduction or complete removal of the cancer.

Dr Ganju, a medical oncologist for Monash Oncology Research Institute (MORI) and Monash Breast Cancer Research Consortium, Monash Medical Centre, Melbourne, Australia, said: “In our study, we were able to show that patients who had higher baseline SUVs and a greater reduction in SUV at the second PET scan, were more likely to respond to the chemotherapy and achieve a complete pathological response. Patients who achieve a complete pathological response are more likely to survive and have a better prognosis.”

MEDICA.de; Source: European CanCer Organisation