Role of 18F-Flurodeoxyglucose Positron-Emission Tomography/Computed Tomography in the Evaluation of Early Response to Neoadjuvant Chemotherapy in Patients with Locally Advanced Triple-Negative Breast Cancer.

BACKGROUND: Response evaluation in locally advanced breast cancer is done through different methods ranging from clinical examination to magnetic resonance imaging, however evaluation with positron-emission tomography/computed tomography (PET/CT) in now being incorporated for the response evaluation. The aim of the present study is to correlate response to neoadjuvant chemotherapy (NACT) with PET/CT scan. MATERIALS AND METHODS: The present study is a retrospective analysis of 30 locally advanced, triple-negative breast cancer patients. PET/CT scan was done pretreatment and post three and six cycles of NACT and was correlated with pathologic complete response (pCR). Responding disease was considered when there was at least a 50% reduction in the longest diameter. RESULTS: The median pretreatment size of the breast lesion in CT scan was 3.9 ± 2.3 cm (2-12 cm) and maximum standardized uptake value (SUVmax) on PET/CT was 8.5 ± 5.5 (2.9-24). Among the responders, the median decrease in size of lesion was 3.2 ± 1.3 cm and median reduction in SUV of the tumor among was -8.1 ± 5.4 and was statistically significant when compared with nonresponders (P < 0.001). CT scan has 66% accuracy and PET has 82% accuracy at post three cycles NACT in predicting the pathological response. PET/CT had higher sensitivity and specificity when compared with CT findings alone in response evaluation. CONCLUSION: PET/CT scan can be considered as a sensitive tool for predicting pCRs and further larger trials are required to establish these findings.

Ki-67 labeling index as a predictor of response to neoadjuvant chemotherapy in breast cancer.

AIMS: To investigate Ki-67 index with regard to its ability to predict achievement of pathologic complete response (pCR) to neoadjuvant chemotherapy (NACT) in breast cancer patient. MATERIAL AND METHODS: It was a prospective observational study, conducted in Department of Medical Oncology, Rajiv Gandhi Cancer Institute & Research Center (RGCIRC), New Delhi from February 2014 to March 2016. A total of 134 patients with Stage II/III breast cancer who underwent NACT followed by surgery at our center were enrolled and analyzed. Before starting the treatment, clinical, tumor-related and treatment-related factors were recorded. Response evaluation was done clinically and radiologically after completion of NACT and pathologically on the surgical specimen. We calculated Ki-67 cut-off of 35% to label it as high by area under Receiver operating characteristic curve analysis for prediction of pCR. RESULTS: Clinical complete response (cCR) was observed in 35/134 (26.1%) patients while pCR was observed in 32/134 (23.9%) patients. On univariate analysis, higher grade (III), high Ki-67 index (>35%) and number of chemotherapy cycles (>3) were associated with better CCR rates. On multivariate analysis, number of chemotherapy cycles (>3) and high Ki-67 index (>35%) were independent predictive factors. For the predictive factors of pCR, univariate analysis showed grade (III), estrogen receptor/progesterone receptor negativity, HER-2 positivity, number of chemotherapy cycles (>3), TNBC and high Ki-67 index (>35%) to be associated with higher pCR rates. On multivariate analysis, Ki-67 index >35% and HER-2 positivity were the only independent predictive factors of pCR. CONCLUSIONS: We suggest 35% as best cut-off for Ki-67 expression for predicting response to NACT and achievement of pCR. Validation of this cut-off is required in larger studies.