Significance of lymph node metastasis in patients with diffuse malignant peritoneal mesothelioma

Background Diffuse malignant peritoneal mesothelioma (DMPM) is a rare and invariably fatal neoplasm. Some studies have shown that cytoreductive surgery (CRS) combined with perioperative intraperitoneal chemotherapy (PIC) achieved an improved survival, as compared to historical controls. However, the significance of lymph node involvement in this disease has never been well defined. Methods One hundred patients with DMPM underwent CRS and PIC at the Washington Hospital Center. The inclusion criteria for surgery consisted of histological diagnosis of DMPM, age <80 years and good performance status. All data were collected prospectively. Lymph node status, seven clinical variables and eight treatment-related prognostic factors were analyzed for survival. Results Seven patients were lymph node positive and they all died of their disease within 2 years after the surgery. The remaining 93 patients had 5- and 7-year survival of 50% and 43%, respectively. Univariate analysis showed that gender (p < 0.001), peritoneal cancer index (p = 0.009), lymph node status (p < 0.001), extra-abdominal invasion (p = 0.026), histological type (p < 0.001), intraoperative blood loss (p = 0.035), completeness of cytoreduction (p < 0.001), intraperitoneal chemotherapy regimen (p = 0.041), and redo cytoreductive surgery (p = 0.022) were significant for survival. Multivariate analysis demonstrated that female gender, lymph node metastasis not detected, epithelial type, and adequate cytoreduction were independently associated with an improved survival. Conclusions CRS and PIC showed an improved survival for DMPM, as compared to historical controls. Lymph node status along with three other prognostic variables was significant in the multivariate analysis.