A number of factors indicating poor prognosis have been identified including: younger age, rectal origin of PM, large prior surgery score (PSS; number of abdominopelvic regions that surgery has been performed for cancer in the past), high grade tumor, signet ring cell histology, presence of lymph node metastases, presence of large volume implantations, presence of distant and non-resectable metastases, size of liver metastases and toxicity of preoperative chemotherapy,peritoneal lavage cytology, malignant ascites, extent of small involvement, and short interval from primary to recurrence in patients with metachronous PM. Further investigation is required in order to better define the exact contributions of these factors to disease outcome