title: Ex Vivo Intra-arterial Methylene Blue Injection in Rectal Cancer Specimens Increases the Lymph-Node Harvest, Especially After Preoperative Radiation.
abstract: BACKGROUND
  The examination of as large a number of lymph nodes as possible in rectal carcinoma resectates is important for exact staging. However, after neoadjuvant radiochemotherapy (RCT), it can be difficult to obtain a sufficient number of lymph nodes. We therefore investigated whether staining with methylene blue via the inferior mesenteric artery can lead to an increase in the yield of lymph nodes in rectal carcinoma tissue after neoadjuvant RCT.
  
  
  METHODS
  In a prospective, unicentric study rectal carcinoma resectates from three consecutive groups of patients were examined (Group I, no staining; Group II, staining with methylene blue; Group III, again no staining). The numbers of lymph nodes examined were compared (a) between the groups and (b) between patients who had not, or who had, received neoadjuvant RCT.
  
  
  RESULTS
  In all, 75 rectal carcinoma preparations were assessed. The yield of lymph nodes investigated before the use of staining (Group I) increased when staining was introduced (Group II), both for the patients without neoadjuvant RCT (20.9 vs. 31.3, p = 0.018) and for those who did receive this (15.0 vs. 35.1; p = 0.003). After withdrawal of the staining procedure (Group III), the lymph-node yield remained high for the patients without neoadjuvant RCT (31.3 vs. 30.4; p = 0.882), but it reverted to a lower value for those who did receive neoadjuvant RCT (35.1 vs. 24.2; p = 0.029). Before the introduction of staining (Group I), significantly fewer lymph nodes were examined for patients who received neoadjuvant RCT (15.0 vs. 20.9; p = 0.039). However, with staining (Group II), no difference was found associated with the use or non-use of neoadjuvant RCT (31.3 vs. 35.1; p = 0.520).
  
  
  CONCLUSIONS
  The use of methylene blue staining of rectal carcinoma preparations leads to a significant increase in the number of lymph nodes examined after neoadjuvant RCT. This can be expected to improve the accuracy of lymph-node staging of neoadjuvant-treated rectal carcinoma.
authors: Department of Surgery, Carl-Thiem-Hospital Cottbus, Thiemstr. 111, 03048, Cottbus, Germany.
authors: Maria
authors: M
authors: Münster
authors: Institute of Pathology, Carl-Thiem-Hospital Cottbus, Thiemstr. 111, 03048, Cottbus, Germany.
authors: Uwe
authors: U
authors: Hanisch
authors: Institute of Pathology, Carl-Thiem-Hospital Cottbus, Thiemstr. 111, 03048, Cottbus, Germany.
authors: Muin
authors: M
authors: Tuffaha
authors: Department of Surgery, Carl-Thiem-Hospital Cottbus, Thiemstr. 111, 03048, Cottbus, Germany.
authors: Rainer
authors: R
authors: Kube
authors: Department of Surgery, Carl-Thiem-Hospital Cottbus, Thiemstr. 111, 03048, Cottbus, Germany. henryptok@aol.com.
authors: Henry
authors: H
authors: Ptok
mesh_terms: D000328:Adult; D000368:Aged; D059186:Chemoradiotherapy, Adjuvant; D004396:Coloring Agents / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007269:Injections, Intra-Arterial; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology*; D008297:Male; D017537:Mesenteric Artery, Inferior; D008751:Methylene Blue / Q000008:administration & dosage*; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D013194:Staining and Labeling
chemical_list: D004396:Coloring Agents; D008751:Methylene Blue