title: Response to chemoradiotherapy and lymph node involvement in locally advanced rectal cancer.
abstract: OBJECTIVE
  To establish the association between lymph node involvement and the response to neoadjuvant therapy in locally advanced rectal cancer.
  
  
  METHODS
  Data of 130 patients with mid and low locally advanced rectal adenocarcinoma treated with neoadjuvant chemoradiation followed by radical surgery over a 5-year period were reviewed. Tumor staging was done by endorectal ultrasound and/or magnetic resonance imaging. Tumor response to neoadjuvant therapy was determined by T-downstaging and tumor regression grading (TRG). Pathologic complete response (pCR) is defined as the absence of tumor cells in the surgical specimen (ypT0N0). The varying degrees TRG were classified according to Mandard's scoring system. The evaluation of the response is based on the comparison between previous clinico-radiological staging and the results of pathological evaluation. χ (2) and Spearman's correlation tests were used for the comparison of variables.
  
  
  RESULTS
  Pathologic complete response (pCR, ypT0N0, TRG1) was observed in 19 cases (14.6%), and other 18 (13.8%) had only very few residual malignant cells in the rectal wall (TRG2). T-downstaging was found in 63 (48.5%). Mean lymph node retrieval was 9.4 (range 0-38). In 37 cases (28.5%) more than 12 nodes were identified in the surgical specimen. Preoperative lymph node involvement was seen in 77 patients (59.2%), 71 N1 and 6 N2. Postoperative lymph node involvement was observed in 41 patients (31.5%), 29 N1 and 12 N2, while the remaining 89 were N0 (68.5%). In relation to ypT stage, we found nodal involvement of 9.4% in ypT0-1, 22.2% in ypT2 and 43.7% in ypT3-4. Of the 37 patients considered "responders" to neoadjuvant therapy (TRG1 and 2), there were only 4 N+ (10.8%) and the remainder N0 (89.2%). In the "non responders" group (TRG 3, 4 and 5), 37 cases were N+ (39.8%) and 56 (60.2%) were N0 (P < 0.001).
  
  
  CONCLUSIONS
  Response to neoadjuvant chemoradiation in rectal cancer is associated with lymph node involvement.
authors.affiliation: Luis J García-Flórez, General and Digestive Surgery Service, Hospital San Agustín, 33401 Avilés, Spain.
authors.forename: Luis J
authors.initials: LJ
authors.lastname: García-Flórez
authors.affiliation: Luis J García-Flórez, General and Digestive Surgery Service, Hospital San Agustín, 33401 Avilés, Spain.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Gómez-Álvarez
authors.affiliation: Luis J García-Flórez, General and Digestive Surgery Service, Hospital San Agustín, 33401 Avilés, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Frunza
authors.affiliation: Luis J García-Flórez, General and Digestive Surgery Service, Hospital San Agustín, 33401 Avilés, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Barneo-Serra
authors.affiliation: Luis J García-Flórez, General and Digestive Surgery Service, Hospital San Agustín, 33401 Avilés, Spain.
authors.forename: Manuel F
authors.initials: MF
authors.lastname: Fresno-Forcelledo
keywords: Chemoradiotherapy; Lymph node involvement; Neoadjuvant therapy; Rectal cancer; Response to treatment