title: Do New pN Subclassifications Proposed by IASLC's Lung Cancer Staging Project Agree with ypN Categories after Trimodality Therapy for Initial N2 Disease?
abstract: The International Association for the Study of Lung Cancer's lung cancer staging project has recently proposed a new subclassification of pN1-2 based on multiplicity of involved nodal stations and presence of skip metastasis. The authors investigated whether this new subclassification agrees with the ypN categories after trimodality therapy for initially N2 disease.
  
  
  
  From March 2001 until June 2014, trimodality therapy consisting of preoperative thoracic radiation therapy concurrent with weekly platinum-based doublet chemotherapy and surgical resection was successfully undertaken in 508 patients after histopathologic confirmation of N2 disease. Data on 481 patients were analyzed and compared with special focus on the current and new pN classification.
  
  
  
  The median duration of overall survival (OS) was 58 months, and the 5-year OS rate of all patients was 48.8%: 62.6% in ypN0; 45.5% in ypN1; 37.6% in ypN2; and 0% in ypN3. Comparisons between neighboring ypN categories showed significant difference between ypN0 and ypN1 (p = 0.028) but not between other categories. The 5-year OS rates according to new ypN subclassification were 48.2% in ypN1a, 39.0% in ypN1b, 52.8% in ypN2a1, 37.9% in ypN2a2, and 32.1% in ypN2b. Although the OS rate of ypN2a1 was numerically higher than those of ypN1b and ypN2b, comparisons between neighboring ypN categories revealed no significant difference.
  
  
  
  The current study was specifically intended to investigate whether ypN categories after trimodality therapy agree with International Association for the Study of Lung Cancer's new pN subclassification. Through the current study, the authors have confirmed that ypN downstaging to ypN0-1 from initial N2 stage is a favorable factor with respect to OS and raised the need for refinement of ypN subcategorization after trimodality therapy.
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Hakyoung
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: ahnyc@skku.edu.
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Ahn
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Hongryull
authors.initials: H
authors.lastname: Pyo
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Dongryul
authors.initials: D
authors.lastname: Oh
authors.affiliation: Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jae Myoung
authors.initials: JM
authors.lastname: Noh
authors.affiliation: Department of Medicine, Division of Hematooncology, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jong-Mu
authors.initials: JM
authors.lastname: Sun
authors.affiliation: Department of Medicine, Division of Hematooncology, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jin Seok
authors.initials: JS
authors.lastname: Ahn
authors.affiliation: Department of Medicine, Division of Hematooncology, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Myung-Ju
authors.initials: MJ
authors.lastname: Ahn
authors.affiliation: Department of Medicine, Division of Hematooncology, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Keunchil
authors.initials: K
authors.lastname: Park
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Yong Soo
authors.initials: YS
authors.lastname: Choi
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jhingook
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jae Ill
authors.initials: JI
authors.lastname: Zo
authors.affiliation: Department of Thoracic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Young Mog
authors.initials: YM
authors.lastname: Shim
authors.affiliation: Departments of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Minju
authors.initials: M
authors.lastname: Lee
authors.affiliation: Departments of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jungho
authors.initials: J
authors.lastname: Han
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017024:Chemotherapy, Adjuvant / Q000379:methods*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000145:classification* / Q000473:pathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011878:Radiotherapy / Q000379:methods*; D055815:Young Adult
keywords: Chemotherapy; Lymph node metastasis; NSCLC; Radiation therapy; Surgery