Predicting Response to Neoadjuvant Chemotherapy Using 18F FDG PET-CT in Patients with Locally Advanced Breast Cancer

OBJECTIVE: The study was aimed to find the utility of 18F FDG PET CT in assessing response to neoadjuvant chemotherapy (NACT) in female patients with locally advanced breast cancer (LABC). METHODS: All willing women with biopsy proven LABC, following clinical evaluation underwent baseline 18F FDG PET CT along with mammosonograpy and contrast enhanced computerized chest radiography (CECT). The response was assessed clinically before each cycle of chemotherapy using RECIST criteria. Those who were progressing clinically were offered alternate chemotherapy or radiation or surgery. Clinical responders were re-evaluated with 18F FDG PET CT, mammosonogram and CT chest before surgery. The pathological response as assed with residual cancer burden score was used as gold standard. RESULTS: Of the 30 women eligible, 26 women underwent repeat evaluation and surgery. The mean age was 49 years, 16 women were postmenopausal and 15 tumors were receptor positive. On final histopathology 15 % had completer response and 46 % were non responders. Using a cut off value of 50% of the baseline SUV(max), PET-CT had sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 64%, 75%, 75%, 65%, and 69%, respectively in differentiating pathological responders from non-responders. CONCLUSION: 18F FDG PET-CT predicted the response with greater accuracy than CT or clinical examination. Hence it can be used to identify non responders early in the course and alternate treatment can be offered to patients.