title: Is total mesorectal excision always necessary for T1-T2 lower rectal cancer?
abstract: BACKGROUND
  The goal of this multicenter study was to clarify the determinants of local excision for patients with T1-T2 lower rectal cancer.
  
  
  METHODS
  Data from 567 consecutive patients who underwent radical resection for T1-T2 lower rectal cancer at 12 institutions between 1991 and 1998 were reviewed. Rates of lymph node metastasis were investigated using a tree analysis, which was hierarchized using independent risk factors for nodal involvement.
  
  
  RESULTS
  The independent risk factors for lymph node metastasis were female gender, depth of tumor invasion, histology other than well-differentiated adenocarcinoma, and lymphatic invasion. According to the first three parameters that can be obtained preoperatively, only 0.99% of the patients without risk factors had lymph node metastasis. On the other hand, even if the lower rectal cancer was at stage T1, women with histological types other than well-differentiated adenocarcinoma had an approximately 30% probability of having lymph node metastasis. Lymphatic invasion was most useful to predict nodal involvement among patients with T2 lower rectal cancer. The rates of lymph node metastasis in T2 patients with and without lymphatic invasion were 32.9% and 9.1%, respectively.
  
  
  CONCLUSIONS
  Gender is one of the most important predictors for lymph node metastasis in patients with early distal rectal cancer. Three parameters, including depth of tumor invasion, histology, and gender, are useful determinants for local excision. Additional studies are required to establish the minimum optimal treatment for T2 lower rectal cancer.
authors: Department of Surgical Oncology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan. h-kobayashi.srg2@tmd.ac.jp
authors: Hirotoshi
authors: H
authors: Kobayashi
authors: Hidetaka
authors: H
authors: Mochizuki
authors: Tomoyuki
authors: T
authors: Kato
authors: Takeo
authors: T
authors: Mori
authors: Shingo
authors: S
authors: Kameoka
authors: Kazuo
authors: K
authors: Shirouzu
authors: Yukio
authors: Y
authors: Saito
authors: Masahiko
authors: M
authors: Watanabe
authors: Takayuki
authors: T
authors: Morita
authors: Jin-Ichi
authors: J
authors: Hida
authors: Masashi
authors: M
authors: Ueno
authors: Masato
authors: M
authors: Ono
authors: Masamichi
authors: M
authors: Yasuno
authors: Kenichi
authors: K
authors: Sugihara
mesh_terms: D000230:Adenocarcinoma / Q000556:secondary / Q000601:surgery*; D013505:Digestive System Surgical Procedures; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011379:Prognosis; D012004:Rectal Neoplasms / Q000473:pathology / Q000601:surgery*; D012307:Risk Factors; D012737:Sex Factors; D015996:Survival Rate