title: Influence of preoperative chemoradiotherapy on the number of lymph nodes retrieved in rectal cancer.
abstract: OBJECTIVE
  To evaluate the relation of preoperative chemoradiotherapy to the number of lymph nodes retrieved in curative intent surgery for rectal cancer.
  
  
  BACKGROUND
  Current guidelines recommend evaluation of least 12 to 14 lymph nodes in rectal cancer. It is well known that lymph nodes retrieval is affected by many factors.
  
  
  METHODS
  This was a retrospective study of 615 patients who underwent curative intent surgery for primary rectal cancer. Preoperative chemoradiotherapy involving 50.4 Gy fractionated radiotherapy and concurrent chemotherapy was performed in patients with locally advanced rectal cancer (clinically T3 or T4). We explored associations between the number of lymph nodes retrieved in the pathologic specimen and patient demographics (age, gender, body mass index [BMI]), treatment (surgeon, sphincter-saving, preoperative chemoradiotherapy), and tumor-related variables (location, stage, histology). After adjustment for other factors, we compared the mean number of obtained lymph nodes between patients treated with preoperative chemoradiotherapy and those treated without preoperative chemoradiotherapy.
  
  
  RESULTS
  Univariate analysis demonstrated that age, BMI, preoperative chemoradiotherapy, location, and stage significantly related the number of lymph nodes retrieved. Multivariate analysis revealed age, BMI, preoperative chemoradiotherapy, and stage as independent factors influencing the number of lymph nodes retrieved. The mean number of lymph nodes adjusted for age, BMI, and stage was significantly lower in patients treated with preoperative chemoradiotherapy than in those treated without preoperative chemoradiotherapy (14.5 vs. 21.5, P < 0.001). The reduction rate by preoperative chemoradiotherapy was 32.6% (7/21.5). In patients who underwent preoperative chemoradiotherapy, advanced age (P < 0.001) and high BMI (P = 0.037) were associated with decreased number of retrieved lymph nodes.
  
  
  CONCLUSIONS
  Preoperative chemoradiotherapy significantly decreased the number of retrieved lymph nodes by approximately 33%. Therefore, the recommended number of retrieved lymph nodes should be adjusted when rectal cancer is treated with preoperative chemoradiotherapy.
authors.affiliation: Center for Colorectal Cancer, Research Institute & Hospital, National Cancer Center, Goyang-si, Gyeonggi-do, Korea.
authors.forename: Yun Hyung
authors.initials: YH
authors.lastname: Ha
authors.forename: Seung-Yong
authors.initials: SY
authors.lastname: Jeong
authors.forename: Seok-Byung
authors.initials: SB
authors.lastname: Lim
authors.forename: Hyo Seong
authors.initials: HS
authors.lastname: Choi
authors.forename: Yong Sang
authors.initials: YS
authors.lastname: Hong
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Chang
authors.forename: Dae Yong
authors.initials: DY
authors.lastname: Kim
authors.forename: Kyung Hae
authors.initials: KH
authors.lastname: Jung
authors.forename: Jae-Gahb
authors.initials: JG
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D012004:Rectal Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy / Q000601:surgery*; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors