Survival Implications of Variation in the Thoroughness of Pathologic Lymph Node Examination in American College of Surgeons Oncology Group Z0030 (Alliance).
BACKGROUND
Accurate pathologic nodal staging mandates effective collaboration between surgeons and pathologists. The American College of Surgeons Oncology Group Z0030 trial (ACOSOG Z0030) tightly controlled surgical lymphadenectomy practice but not pathologic examination practice. We tested the survival impact of the thoroughness of pathologic examination (using the number of examined lymph nodes as a surrogate).


METHODS
We re-analyzed the mediastinal lymph node dissection arm of ACOSOG Z0030, using logistic regression and Cox proportional hazards models.


RESULTS
Of 513 patients, 435 were pN0, 60 were pN1, and 17 were pN2. The mean number of mediastinal lymph nodes examined was 13.5, 13.1, and 17.1; station 10 lymph nodes were 2.4, 2.7, and 2.6; station 11 to 14 nodes were 4.6, 6.1, and 6.7; and total lymph nodes were 19.7, 21.3, and 25.4 respectively. The pN category and histologic evaluation were associated with increased number of examined intrapulmonary lymph nodes. Patients with pN1 had more non-hilar N1 nodes than patients with pN0, patients with N2 had more N2 nodes examined than patients with pN0 or pN1. Patients with pN0 had better survival with examination of more N1 nodes; patients with pN1 had better survival with increased mediastinal nodal examination; the likelihood of discovering N2 disease was significantly associated with increased examination of mediastinal and non-hilar N1 lymph nodes.


CONCLUSIONS
Despite rigorously standardized surgical hilar/mediastinal lymphadenectomy, the number of lymph nodes examined was associated with the likelihood of detecting nodal metastasis and survival. This may indicate an effect of incomplete pathologic examination.
Multidisciplinary Thoracic Oncology Program, Baptist Cancer Center, Memphis, Tennessee. Electronic address: rosarogi@bmhcc.org.
Raymond U
RU
Osarogiagbon
Alliance Statistics and Data Center, Mayo Clinic, Rochester, Minnesota.
Paul A
PA
Decker
Division of Biostatistics and Epidemiology, Weill Cornell Medical College, New York, New York.
Karla
K
Ballman
Department of Surgery, Mayo Clinic, Rochester, Minnesota.
Dennis
D
Wigle
Department of Surgery, Mayo Clinic, Rochester, Minnesota.
Mark S
MS
Allen
Department of Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
Gail E
GE
Darling
D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis / Q000556:secondary / Q000601:surgery*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000601:surgery*; D008197:Lymph Node Excision / Q000379:methods*; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008482:Mediastinum; D009367:Neoplasm Staging; D011013:Pneumonectomy / Q000379:methods*; D011379:Prognosis; D016016:Proportional Hazards Models; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014481:United States