title: Importance of Absent Neoplastic Epithelium in Patients Treated With Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy.
abstract: BACKGROUND
  The importance of absent neoplastic epithelium in specimens from cytoreductive surgery (CRS) is unknown. This study aimed to investigate the prevalence and prognostic value of histopathology without neoplastic epithelium in patients treated with CRS and hyperthermic intraperitoneal chemotherapy (HIPEC).
  
  
  METHODS
  Data were extracted from medical records and histopathology reports for patients treated with initial CRS and HIPEC at Uppsala University Hospital, Sweden, between 2004 and 2012. Patients with inoperable disease and patients undergoing palliative non-CRS surgery were excluded from the study. Patients lacking neoplastic epithelium in surgical specimens from CRS, with or without mucin, were classified as "neoplastic epithelium absent" (NEA), and patients with neoplastic epithelium were classified as "neoplastic epithelium present" (NEP).
  
  
  RESULTS
  The study observed NEA in 78 of 353 patients (22 %). Mucin was found in 28 of the patients with NEA. For low-grade appendiceal mucinous neoplasms and adenomas, the 5-year overall survival rate was 100 % for NEA and 84 % for NEP, and the 5-year recurrence-free survival rate was 100 % for NEA and 59 % for NEP. For appendiceal/colorectal adenocarcinomas (including tumors of the small intestine), the 5-year overall survival rate was 61 % for NEA and 38 % for NEP, and the 5-year recurrence-free survival rate was 60 % for NEA and 14 % for NEP. Carcinoembryonic antigen level, peritoneal cancer index, and completeness of the cytoreduction score were lower in patients with NEA.
  
  
  CONCLUSIONS
  A substantial proportion of patients undergoing CRS and HIPEC have NEA. These patients have a favorable prognosis and a decreased risk of recurrence. Differences in patient selection can affect the proportion of NEA and hence explain differences in survival rates between reported series.
authors.affiliation: Department of Surgical Sciences, Colorectal Surgery, Uppsala University, Uppsala, Sweden. malin.enblad@surgsci.uu.se.
authors.forename: Malin
authors.identifier: http://orcid.org/0000-0001-5900-0900
authors.initials: M
authors.lastname: Enblad
authors.affiliation: Department of Surgical Sciences, Colorectal Surgery, Uppsala University, Uppsala, Sweden.
authors.forename: Helgi
authors.initials: H
authors.lastname: Birgisson
authors.affiliation: Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.
authors.forename: Alkwin
authors.initials: A
authors.lastname: Wanders
authors.affiliation: Department of Surgical Sciences, Colorectal Surgery, Uppsala University, Uppsala, Sweden.
authors.forename: Filip
authors.initials: F
authors.lastname: Sköldberg
authors.affiliation: Department of Surgical Sciences, Colorectal Surgery, Uppsala University, Uppsala, Sweden.
authors.forename: Lana
authors.initials: L
authors.lastname: Ghanipour
authors.affiliation: Department of Surgical Sciences, Colorectal Surgery, Uppsala University, Uppsala, Sweden.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Graf
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000473:pathology* / Q000628:therapy; D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001063:Appendiceal Neoplasms / Q000473:pathology* / Q000628:therapy; D010478:Chemotherapy, Cancer, Regional Perfusion; D015179:Colorectal Neoplasms / Q000473:pathology* / Q000628:therapy; D003131:Combined Modality Therapy; D065426:Cytoreduction Surgical Procedures; D004848:Epithelium / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006979:Hyperthermia, Induced; D007274:Injections, Intraperitoneal; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010534:Peritoneal Neoplasms / Q000473:pathology* / Q000628:therapy; D011379:Prognosis; D015996:Survival Rate