title: Lymph node yield after colectomy for cancer: is absence of mismatch repair a factor?
abstract: BACKGROUND
  Nodal staging is crucial in determining the use of adjuvant chemotherapy for colon cancer. The number of metastatic lymph nodes has been positively correlated with the number of lymph nodes examined. Current guidelines recommend that at minimum 12 to 14 lymph nodes be assessed. In some studies, mismatch repair deficiency has been associated with lymph node yield.
  
  
  OBJECTIVE
  The purpose of this work was to determine whether mismatch repair-deficient colorectal tumors are associated with increased lymph node yield.
  
  
  METHODS
  We queried an institutional database to analyze colectomy specimens with immunohistochemistry for mismatch repair genes in patients treated for colorectal cancer between 1999 and 2012. Before 2006, immunohistochemistry was performed at the request of an oncologist or surgeon. After 2006, it was routinely performed for patients <50 years of age. We measured the association of clinical and pathologic features with lymph node quantity. Fourteen predictors and confounders were jointly analyzed in a multivariable linear regression model.
  
  
  METHODS
  The study was conducted at a single tertiary care institution.
  
  
  METHODS
  Tissue specimens from 256 patients were reviewed.
  
  
  METHODS
  The correlation of tumor, patient, and operative variables to the yield of mesenteric lymph nodes was measured.
  
  
  RESULTS
  Of 256 colectomy specimens reviewed, 94 had mismatch repair deficiency. On univariate analysis, mismatch repair deficiency was associated with lower lymph node yield, older patient age, right-sided tumors, and poor differentiation. The linear regression model identified 5 variables with independent relationships to lymph node yield, including patient age, specimen length, lymph node ratio, perineural invasion, and tumor size. A positive correlation was observed with tumor size, specimen length, and perineural invasion. Tumor location had a more complex, nonlinear, quadratic relationship with lymph node yield; proximal tumors were associated with a higher yield than more distal lesions. Mismatch repair deficiency was not independently associated with lymph node yield.
  
  
  CONCLUSIONS
  Mismatch repair immunohistochemistry based on patient age, family history, and pathologic features may reduce the generalizability of these results. Our sample size was too small to identify variables with small measures of effect. The retrospective nature of the study did not permit a true assessment of the extent of mesenteric resection.
  
  
  CONCLUSIONS
  Patient age, length of bowel resected, lymph node ratio, perineural invasion, tumor size, and tumor location were significant predictors of lymph node yield. However, when controlling for surgical and pathologic factors, mismatch repair protein expression did not predict lymph node yield.
authors: 1 Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, New York 2 Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York 3 Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, New York.
authors: Tushar
authors: T
authors: Samdani
authors: Molly
authors: M
authors: Schultheis
authors: Zsofia
authors: Z
authors: Stadler
authors: Jinru
authors: J
authors: Shia
authors: Tiffany
authors: T
authors: Fancher
authors: Justine
authors: J
authors: Misholy
authors: Martin R
authors: MR
authors: Weiser
authors: Garrett M
authors: GM
authors: Nash
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D001932:Brain Neoplasms / Q000473:pathology*; D003082:Colectomy / Q000379:methods*; D003110:Colonic Neoplasms / Q000235:genetics / Q000473:pathology / Q000601:surgery; D015179:Colorectal Neoplasms / Q000473:pathology*; D053843:DNA Mismatch Repair; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008197:Lymph Node Excision / Q000379:methods*; D008198:Lymph Nodes / Q000473:pathology / Q000601:surgery; D008207:Lymphatic Metastasis / Q000235:genetics / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009386:Neoplastic Syndromes, Hereditary / Q000473:pathology*; D011379:Prognosis; D018570:Risk Assessment; D013223:Statistics as Topic; D015996:Survival Rate; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor