Detection of Peritoneal Micrometastasis in Gastric and Pancreatic Cancer in Peritoneal Wash Samples

We are undertaking a study of patients with gastric or pancreatic cancer. A common place for cancer to return after surgery for gastric or pancreatic cancer is the inside lining of the abdomen, called "peritoneal metastasis". At the time of surgery, washing the abdomen with a mild salt solution may reveal free cancer cells in the abdomen which could develop into peritoneal metastasis. Recently, surgeons here at Memorial Sloan-Kettering have found that patients who have these cells develop peritoneal metastases and are better treated with chemotherapy rather than surgery. Sometimes, though, these cells might be present but cannot be found by using current techniques. We are trying to figure out a better way to find these free cancer cells. This could improve our treatment of patients with gastric and pancreatic cancer. We need "negative control" population to which we can compare the peritoneal washings of these cancer patients.

Positive peritoneal cytology is a predictor of poor outcome in gastric cancer. These patients generally have a prognosis similar to patients who are clinically or radiologically classified as having Stage IV disease. Similar, although fewer, observations have been made in patients with pancreatic cancer. If identified prior to scheduled resection, an extensive operation may not be required. The purpose of this pilot trial is to investigate the ability of a quantitative RT-PCR assay to detect cancer cells in peritoneal washings of patients undergoing laparoscopy for gastric or pancreatic cancer. This assay may detect mRNA overly expressed in gastric or pancreatic cancer patients with malignant cells in the peritoneum which cannot be detected by less sensitive means. Results of this assay will be compared to cytology results, as detected by standard Papanicolaou staining, during routine laparoscopic peritoneal washings in the absence of visible M1 disease. We anticipate enrolling 50 gastric cancer patients and 50 pancreatic cancer patients who will be undergoing laparoscopy as part of their initial management. We plan to enroll 30 patients undergoing laparoscopy for a presumed benign condition (e.g., gallstones, prophylactic bilateral salpingo-oophorectomy [BSO]) as negative controls. We estimate accrual will take approximately 12 months. Once this assay is established with this pilot study, we plan to evaluate prospectively the incidence, predictors, and clinical significance of positive cytology, as detected by standard Papanicolaou stainingand RT-PCR of tumor markers. This study does not conflict with any existing protocol at Memorial Hospital.

• Gastric and Pancreatic Cancer

• OTHER: washings for experimental marker testing

• 06-022