[Role of the pathologist in the processing of adenocarcinoma of the stomach, oesophagogastric junction and lower third of the oesophagus].

Adenocarcinoma of the stomach, oesophagogastric junction and lower oesophagus remains a major global public health issue. Recently, the introduction of neoadjuvant chemotherapy in the treatment of these cancers has changed the pathological processing of the surgical resection specimens of these patients. The neoadjuvant treatment induces histological changes of the tumour called "tumour response". This tumour response needs to be evaluated, even if at present, there is no adaptation of the adjuvant chemotherapy to the histological tumour response. Several grading systems have been proposed for the different tumour sites (lower oesophagus, oesophagogastric junction and stomach). We will discuss first the macroscopic processing of the surgical resection specimens and then the different ways of assessing the histological response to chemotherapy. A standardized assessment of the histological tumour response is a necessary prerequisite for future studies looking at the adaptation of chemotherapy depending on the histological tumour response.