Cancer: Early FDG PET identifies patients unresponsive to chemotherapy
Research published in this month’s issue of Cancer suggests that early FDG-PET imaging during preoperative chemotherapy could identify patients with estrogen receptor-positive breast cancer tumors who will not respond optimally to preoperative chemotherapy.

“Patients who had a pathologic complete response or minimal residual disease in the tumor and an absence of cancer cells in ipsilateral axillary lymph nodes were defined as having obtained an optimal pathologic response, whereas all the other conditions were classified as a pathologic non response,” wrote Andrea A. Martoni, MD from the medical oncology unit at S. Orsola-Malpighi University Hospital in Bologna, Italy, and colleagues.

In the study, 34 patients, who received preoperative chemotherapy from six to eight cycles for breast cancer, were monitored by 18F-FDG-PET, and the maximal standardized uptake value percentage changes (SUV) were compared with the pathologic response rate.

Martoni and colleagues found that out of 34 patients, 21 percent achieved an optimal pathologic response (three patients had a pathologic complete response, and four patients had minimal residual disease).

According to the researchers, the SUV threshold value required to predict an optimal pathologic response was 50 percent, after the second cycle of preoperative chemotherapy.

Martoni and colleagues found that 76 percent had a SUV greater than 50 percent (seven patients who had a optimal pathologic response and 19 patients who had pathologic non response). "All eight patients with SUV less than 50 percent had a pathologic nonresponse and had estrogen receptor-positive tumors,” they wrote

Thus, early evaluation of metabolic response by 18F-FDG-PET was able to identify 30 percent of patients with estrogen receptor-positive tumors who were non responsive to chemotherapy, the researchers concluded.