The prediction of response to chemotherapy in patients with oesophago-gastric cencer using positron emission tomography

Conventional anatomical imaging relies on changes in tumour volume, which do not become appreciable until late. Positron Emission Tomography (PET, using metabolically active tracers) offers an alternative, as metabolic changes occur prior to volume reduction. 18FDG PET, monitoring glucose uptake in cells, has been used with some success. 11C-Choline PET, monitoring cellular proliferation, may be more accurate. 18 patients with tumours at or around the gastro-oesophageal junction, underwent PET imaging with both 18FDG and 11C-Choline prior to and at day seven and fourteen into the first cycle of the chemotherapy (neo-adjuvant and palliative). Tumour uptake of each tracer was determined using SUV and Patlak analysis. The initial tumour tracer uptake and the change in uptake over time were correlated with tumour regression grade, pathological response, survival and cellular ki-67 expression. All 18 primary tumours were visualised with 18FDG PET in contrast to 16/18 with 11C-Choline. Four out of nine (44%) patients had a pathological response following neo-adjuvant chemotherapy. Pathological responders had a median survival of 16.1 months in comparison to non responders of 19.0 months (p=0.978). At day 14, tumours with less than median reduction in 11C-Choline uptake (Patlak) had a median survival of 15.4 months compared to 10.9 months for those with a greater than median reduction (p=0.069). Initial and change in 11C-Choline or 18FDG uptake did not correlate with ki-67 tumour count. Tumours with less than the median reduction in ki-67 count following chemotherapy had a median survival of 12.8 months compared to those with a greater than median reduction 14.7 months (p=0.319). Although limited by small numbers, the change in 11C-Choline uptake at day fourteen into the first chemotherapy cycle, best predicts survival for tumours at or around the gastro-oesophageal junction. 11C-Choline uptake did not directly correlate with ki-67 expression.EThOS - Electronic Theses Online ServiceGBUnited Kingdo