title: Clinical benefit of surgery for stage IV colorectal cancer with synchronous peritoneal metastasis.
abstract: BACKGROUND
  Peritoneal metastasis is well-known as a poor prognostic factor in patients with colorectal cancer. It is important to improve the prognosis of patients with colorectal cancer and synchronous peritoneal metastasis. This study aimed to clarify the factors affecting R0 resection and the prognosis of colorectal cancer patients with synchronous peritoneal metastasis.
  
  
  METHODS
  We investigated the data of patients with stage IV colorectal cancer between 1991 and 2007 in 16 hospitals that were members of the Japanese Society for Cancer of the Colon and Rectum.
  
  
  RESULTS
  Of the 564 colorectal cancer patients with synchronous peritoneal metastases, 341 also had hematogenous metastases. The 5-year overall survival rates in patients with and without R0 resection were 32.4 and 4.7 %, respectively. A Cox proportional hazards model showed that histologic type of poorly differentiated adenocarcinoma, regional lymph node metastasis, liver metastasis, chemotherapy after surgery, R0 resection, the Japanese classification of peritoneal metastasis, and the size of peritoneal metastases were independent prognostic factors. Of the 564 patients, 28.4 % had R0 resection. The Japanese classification of peritoneal metastasis (P1-P2, p = 0.0024) and absence of hematogenous metastases (p < 0.0001) were associated with R0 resection.
  
  
  CONCLUSIONS
  P1-P2 peritoneal metastasis and the absence of hematogenous metastasis were the most favorable factors benefiting from synchronous resection of peritoneal metastasis. In addition, chemotherapy after surgery was essential.
authors.affiliation: Center for Minimally Invasive Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan, h-kobayashi.srg2@tmd.ac.jp.
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kotake
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Funahashi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Hase
authors.forename: Koichi
authors.initials: K
authors.lastname: Hirata
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Iiai
authors.forename: Shingo
authors.initials: S
authors.lastname: Kameoka
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Kanemitsu
authors.forename: Koutarou
authors.initials: K
authors.lastname: Maeda
authors.forename: Akihiko
authors.initials: A
authors.lastname: Murata
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ohue
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shirouzu
authors.forename: Keiichi
authors.initials: K
authors.lastname: Takahashi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Watanabe
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yano
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Yatsuoka
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Hashiguchi
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sugihara
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000556:secondary* / Q000601:surgery*; D000368:Aged; D017024:Chemotherapy, Adjuvant; D015179:Colorectal Neoplasms / Q000473:pathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D007564:Japan; D008113:Liver Neoplasms / Q000556:secondary*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D018365:Neoplasm, Residual; D010534:Peritoneal Neoplasms / Q000145:classification / Q000473:pathology* / Q000556:secondary; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate