Utility of hybrid SPECT/CT in Sentinel Lymph Node mapping, and 18F FDG-PET/CT for treatment response evaluation in cancer patients

Abstract: The Sentinel Lymph Node Biopsy (SLNB) method is currently well established in the staging of clinically node-negative breast cancer. However, there is some debate concerning the reliability of this method following previous breast surgery. The SLNB method may also be a valuable tool in the staging of oesophageal cancer or cancer of the gastro-oesophageal junction (GOJ), though there are also indications that the method may be less reliable in more advanced cases. Moreover, the impact of a history of neoadjuvant treatment with either chemo-radiotherapy or chemotherapy alone on lymphatic drainage patterns from the oesophagus or GOJ is not well understood. Therefore, there exists a need to further investigate the SLNB method in this patient group. The addition of neoadjuvant therapy in patients with cancer of the oesophagus or GOJ has been shown to improve long-term survival when compared to surgery alone, but there is a need for better diagnostic tools to evaluate the clinical effects of neoadjuvant therapy in this patient group. This thesis had two main aims. The first aim was to evaluate the utility of hybrid SPECT/CT lymphoscintigraphy in patients with lesions of the breast, or lesions of the oesophagus or GOJ. The second aim was to evaluate the predictive value of 18F-FDG PET/CT in regard to histological response following neoadjuvant treatment in patients with cancer of the oesophagus or GOJ. Paper I: In this study including patients with benign breast lesions, and using SPECT/CT lymphoscintigraphy prior to, and six weeks following a diagnostic breast excision, with the non-operated breasts serving as a control group. We observed no statistically significant differences in reproducibility between the operated and non-operated breasts regarding SLN detection. Paper II: In this study including patients with cancer of the oesophagus/GOJ and using hybrid SPECT/CT lymphoscintigraphy. SPECT/CT yielded a high number of detected Sentinel Lymph Nodes. Another aim was to investigate the overall performance of the SLNB method in this patient group, however the accuracy of the Sentinel Lymph Node Biopsy method in the current patient population was poor. Paper III: In this study investigating the effect of neoadjuvant chemo-radiotherapy on tumour lymphatic drainage patterns in patients with cancer of the oesophagus or GOJ using sequential SPECT/CT lymphoscintigraphy before and following chemo-radiotherapy, but before surgery. The reproducibility of SLN detection was very poor. The SLNB method may be unreliable in patients with cancer of the oesophagus/GOJ with a history of previous neoadjuvant chemo-radiotherapy or chemotherapy. Neoadjuvant chemo-radiotherapy in fact appears to have a considerable impact on lymphatic drainage patterns from the oesophagus or GOJ regarding SLN detection. Paper IV: In this study including patients with cancer of the oesophagus/GOJ. randomised to either neoadjuvant chemo-radiotherapy or neoadjuvant chemotherapy and using consecutive 18F-FDG PET/CT examinations. Changes in PET parameters were studied in relation to post- operative histological response in the primary tumour. In particular, changes to the hitherto seldom-used Standardized Uptake Ratio (SUR) PET-parameter was of interest. When pooling the two treatment arms, there was found to be a statistically significant difference in reduction of SUR in patients with histological response compared to patients with little or no histological response. However, it was not possible to predict a complete histological response.