Recurrence of Optimally Treated Malignant Peritoneal Mesothelioma with Cytoreduction and Heated Intraperitoneal Chemotherapy.

BACKGROUND: The prognosis for patients with diffuse malignant peritoneal mesothelioma has dramatically improved with cytoreductive surgery and intraperitoneal chemotherapy. Little is known about disease recurrence after treatment. We analyzed the time to and predictors of recurrence in a large cohort of optimally treated patients.

METHODS: We examined 113 patients completing a two-stage cytoreduction and intraperitoneal chemotherapy protocol. All patients achieved optimal surgical resection with completeness of cytoreduction (CC) score ≤ 1 and were divided into two groups based on absence (Group A) or presence (Group B) of gross disease at the outset of the second operation. Predictors of disease recurrence and recurrence-free survival (RFS) were determined using Cox proportional hazard regression modeling, and estimates were obtained by using the Kaplan-Meier method.

RESULTS: Forty-six percent of patients had no gross evidence of disease at the second operation; the remaining 54% were cytoreduced to CC ≤ 1 (Group B). Forty-two percent of patients developed disease recurrence with a median recurrence-free survival of 38.5 months for the cohort; 79% of these received a form of iterative treatment. There was no statistically significant difference in recurrence-free survival between Group A (median RFS: 44.6 months) and B (median RFS: 35.5 months) (log-rank test, p = 0.06). Additionally, the only variable significantly associated with RFS was male gender (hazard ratio [HR] 1.98, 95% confidence interval [CI] 1.16-3.38).

CONCLUSIONS: Absence of gross disease at the second operation was not statistically protective against recurrence compared with presence of quantifiable residual disease (Group B) that was effectively cytoreduced. Long-term disease surveillance is recommended, because recurrence continues years after treatment. Where a question of recurrence arises on surveillance, males may benefit from a higher degree of suspicion.