Purpose: Regional axillary lymph node status has remained the single most independent variable to predict prognosis both in terms of disease recurrence and survival. This study aimed to prospectively assess sequential [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET) findings as early predictors of axillary lymph node response to neoadjuvant chemotherapy in stage II and III breast cancer patients.
Methods: Images were acquired with a PET/CT scanner in 52 patients after administration of FDG (5 MBq/kg) at baseline and after the first, second, third and sixth course of chemotherapy before surgery. Clinical examination and ultrasound (US) were used to assess the size of axillary nodes. Decrease in the standardized uptake value (SUV) with PET corrected or not for partial volume effects was compared to the pathological response.
Results: The sensitivity, specificity and accuracy of axillary node staging was higher with PET (75, 87 and 80%) than with US (50, 83 and 65%), and even more so when PET images were corrected for partial volume effects (86, 83 and 84%). While FDG uptake did not vary much in non-responders, as confirmed by histopathological analysis, it markedly decreased to baseline levels in responders (p < 10(-5)). Fifty per cent of baseline SUV was considered the best cutoff value to distinguish responders from non-responders. The sensitivity, specificity, negative predictive value and accuracy of FDG PET after one course of chemotherapy were, respectively, 96, 75, 95 and 84%.
Conclusion: The pathological status of regional axillary lymph nodes in stage II and III breast cancer patients could be accurately predicted after one course of neoadjuvant chemotherapy based on FDG PET images.