I went into the hospital today fro a further check prior to my next chemotherapy on Saturday. They had the CT result, which has shown a 20% reduction in size of the tumor after 4 courses. Although this does not sound much, the tumor is in a hollow tube, so we are talking about its external diameter. Since the tube seems to have started working I think I can assume that the internal diameter is larger so the thickened wall is less. Smaller peritoneal thickenings are also less on the scan, so all in all a good result. I am certainly feeling better.
The oncologist agreed with my hypothesis.