A young woman with gastric cardiac malignant GIST involving lower esophagus underwent neoadjuvant imatinib mesylate. When can we say it is the best time for the surgeon to operate: by duration of treatment just like the TPF neoadjuvant chemotherapy for hypopharyngeal cancer? or by achieving the best response? In the latter, how may one evaluate the best response?
Hi! As the primary aim of neoadjuvant therapy in this setting is to improve chance for R0 resection (resectability) the best response is maximal decrease in tumor volume and metabolic activity (secondary). So, when you rich plato in tumor volume - it's best response (further treatment will not improve surgical outcome and resectability).
In a case of GIST I am preferring volume reduction as a response criterion. After initiation of TKI treatment most GISTs demonstrated reduced activity at PET-CT which not correlates with pathological response.
Prof. Julianov, good point, thanks. In this patient, more than partial remission by RECIST has been achieved. My question is the same, when can we know that will be a best response and further treatment will just render a plateau state.
I am usually predefining the response which I need to perform comfortably R0. In this particular case it will depends on tumor volume and the type of the planned surgery. On the other hand it is preferable to spare as much as possible of the esophageal length and distal stomach. Proximal gastrectomy (both open or laparoscopic) is my preference in a case of GIST with this location. However there is no high-grade evidence to guide the decision when to operate. It seems logical to wait even complete response but in a case of gastric GIST responding tumors usually are complicated with bleeding which sometimes is severe and require urgent surgery. The patient must be informed and the surgeon prepared for that.