title: Secondary cytoreduction and perioperative intraperitoneal chemotherapy after initial debulking of pseudomyxoma peritonei: a study of timing and the impact of malignant dedifferentiation.
abstract: BACKGROUND
  Cytoreductive surgery and perioperative intraperitoneal chemotherapy (PIC) is recognized as an effective treatment modality for patients with pseudomyxoma peritonei. This study investigates its role as a secondary definitive treatment procedure after earlier primary treatments.
  
  
  METHODS
  Patients with pseudomyxoma peritonei undergoing secondary cytoreduction combined with PIC were identified from a prospective database. Retrospective analysis investigated the outcomes, prognostic factors, critical time points, and impact of malignant dedifferentiation. Survival analysis was performed via the Kaplan-Meier method and compared via the log-rank test.
  
  
  RESULTS
  The median time to progression after secondary cytoreduction was 28 months (95% CI 14 to 41 months), median survival was 97 months (95% CI 82 to 113 months), and 10-year survival was 25%. Median overall survival from initial diagnosis was 17 years and 10-year survival rate was 75%. Forty-five patients remained disease free (63%). Requiring an urgent treatment (waiting time < 60 days) after disease progression (p = 0.045) and having moderate or severe symptoms (p = 0.033) were associated with a shorter time to progression. Improved survival was associated with patients who had low-grade tumors (p = 0.029), and those who required less urgent treatment (wait > 30 days) after disease progression (waiting up to 15 days, p = 0.010; waiting up to 30 days, p = 0.005). Malignant dedifferentiation appeared to affect survival from initial diagnosis (p = 0.062) and after secondary cytoreduction (p = 0.006).
  
  
  CONCLUSIONS
  Secondary cytoreduction with PIC achieves long-term survival. Tumors that undergo malignant dedifferentiation appear to adversely affect survival, and this may support the rationale for early definitive treatment with cytoreduction and PIC.
authors: Department of Surgery, University of New South Wales, Kogarah, Sydney, Australia.
authors: Terence C
authors: TC
authors: Chua
authors: Abdulaziz
authors: A
authors: Al-Zahrani
authors: Akshat
authors: A
authors: Saxena
authors: Winston
authors: W
authors: Liauw
authors: Jing
authors: J
authors: Zhao
authors: David L
authors: DL
authors: Morris
mesh_terms: D000328:Adult; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D002454:Cell Differentiation; D002471:Cell Transformation, Neoplastic; D018450:Disease Progression; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D007263:Infusions, Parenteral; D008297:Male; D008875:Middle Aged; D016685:Mitomycin / Q000008:administration & dosage; D010534:Peritoneal Neoplasms / Q000188:drug therapy* / Q000601:surgery*; D011379:Prognosis; D011553:Pseudomyxoma Peritonei / Q000188:drug therapy* / Q000601:surgery*; D012189:Retrospective Studies; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D016685:Mitomycin; D005472:Fluorouracil