Significance of Peritoneal Washing Cytology Before and After Neoadjuvant Chemotherapy in Patients With Esophagogastric-junction Cancer

Background:

The prevalence of gastroesophageal-junction cancer (cancer between the distal part of the oesophagus, and proximal part of the stomach/GEJ-cancer) is increasing in Denmark with more than 400 patients per year. The 5-year overall survival is less than 10% for the 2/3 of the patients, which are not considered resectable. Even for the 1/3, which is treated with surgical intervention and neoadjuvant chemotherapy the overall-survival is approximately 30%.

The current Danish intended curative treatment consists of esophagectomy (surgical resection of the oesophagus with extended lymphadenectomy in abdomen and thorax (removal of lymphnodes)). Furthermore, perioperative chemotherapy consists of 6 series neoadjuvant chemotherapy (3 series before, and 3 series after operation).

Unresectable patients receive palliative chemotherapy and no resection. Peritoneal washing cytology (PWC) is a recommended prediagnostic modality in gastric cancer patients. The method is used to detect free peritoneal cancer cells in the abdominal cavity even when macroscopic carcinomatosis is not present (i.e. the cancer has spread to other parts of the abdomen).

Carcinomatosis can be found in up to 19% in gastric cancer patients often in the peritoneum. Positive peritoneal cytology (C1) can be identified in up to 7% of gastric cancer patients without metastases (C1M0), i.e. malignant cells can be identified in the peritoneal washing, but tumor spread has not been identified.

Lots of studies indicate that C1-disease is an independent prognostic predictor for decreased survival, and increased recurrence rate, comparable with M1 patients (i.e. patients with distant metastases).

The American Joint Committee on cancer recommends that C1 patients should be treated non-surgically - even when M1 disease has not been identified.

On the basis of the above, PWC can be used to identify patients at greater risk for recurrence, and thereby not candidates for intended curative treatment.

It is a fact, though, that C1M0 patients have a better survival than C1M1 patients. Currently, there is no level-1 evidence for specific treatment of C1M0 patients, why further research is required to approach this patient group in the most comprehensive way. The focus group of our study is therefore C1M0 patients, because of the difference in opinions. Furthermore most evidence is based on gastric carcinomas, why GEJ-cancer patients are the group, we will examine.

Purpose:

Peritoneal washing cytology (PWC) is performed as a standard prediagnostic modality at Rigshospitalet, for patients with gastric- and GEJ cancer, considered resectable at preceding multidisciplinary conference. Most studies in the past 20-years have focused on gastric cancer, and not specifically GEJ-cancer.

This study will determine the usefulness of peritoneal washing cytology, and thereby verifying our own standard regarding GEJ-cancer. Furthermore, we will determine the effect of neoadjuvant chemotherapy on free peritoneal tumor cells and its correlation with overall survival.

This study is intended as a validation of our own standard.