Influence of microscopic malignant peritoneal mesothelioma on posttreatment survival

Abstract

e15534 Background: Progression of malignant peritoneal mesothelioma to clinically evident disease is poorly understood. Operative cytoreduction and post-operative intraperitoneal chemotherapy, followed by a second operative cytoreduction with heated intraoperative intraperitoneal chemotherapy is protocol at Columbia University. Our ability to assess presence of microscopic disease at a unique second operation provides in vivo insight into disease progression. Methods: Operative, pathology and oncologist records were reviewed for 98 consecutive patients with peritoneal mesothelioma treated between 5/95 and 1/08. Microscopic disease was defined as positive pathology on random biopsies in the absence of gross disease at second operation, and disease-free as absence of gross and microscopic disease. Survival was defined as time from first operation to death or last follow-up. Survival and recurrence were compared using the Kaplan Meier and log-rank methods, and correlations by Fisher's exact method. Results: 98 first and 69 second operations were performed. Patients were 59% male, 88% Caucasian and mean age was 52. At the second operation, 38 had gross disease, 23 were disease-free and 8 had microscopic disease. Median follow-up was 21 months, median overall survival was 48 months, and median survival for the epithelial subtype was 64 months. There was no significant difference in survival between disease- free and microscopic pathologies (log-rank p<0.69). 72% of disease-free (SE 11%) and 80% (SE 18%) of those with microscopic disease were alive at 96 months. 16% of disease-free and 7% of patients with microscopic disease had a recurrence (p<0.4). The time to clinical recurrence for both disease-free and microscopic disease was not significantly different (log-rank p<0.88). Conclusions: Survival and clinical recurrence in those with microscopic disease, none of whom were treated for this entity, were not significantly different from those who were disease-free at the second operation. These in vivo after treatment findings suggest that malignant peritoneal mesothelioma may progress slowly from microscopic to clinical disease and can be closely monitored rather than aggressively treated after initial cytoreduction and intraperitoneal chemotherapy. No significant financial relationships to disclose.