title: Prognostic Impact of Newly Proposed M Descriptors in TNM Classification of Non-Small Cell Lung Cancer.
abstract: The International Association for the Study of Lung Cancer recently proposed new M descriptors for the next edition of the TNM classification for NSCLC, subdividing the current M1b category into two subcategories: M1b, which indicates a solitary extrathoracic metastasis in a single organ, and M1c, which indicates multiple extrathoracic metastasis. The purpose of this study was to validate the prognostic value of the newly proposed M descriptors in an independent cohort with multivariate and subgroup analysis.
  
  
  
  A total of 1024 patients in a consecutive lung cancer database who had stage IV NSCLC treated between 2011 and 2014 were analyzed. Newly proposed M staging was used for classification and comparison of survival. Adjustment for other clinical covariates and subgroup analysis was conducted.
  
  
  
  According to the newly proposed M descriptors, 262 patients (25.6%), 152 patients (14.8%), and 610 patients (59.6%) were classified into the subgroups M1a, M1b, and M1c, respectively. The median overall survival times were 22.5, 17.8, and 13.6 months for the M1a, M1b, and M1c groups, respectively (p < 0.001). After adjustment for other covariates, Cox proportional hazards regression revealed statistically significantly shorter overall survival for the M1b group than for the M1a group (hazard ratio = 1.30; 95% confidence interval: 1.03-1.65, p = 0.03) and for the M1c than the M1b group (hazard ratio = 1.57; 95% confidence interval: 1.28-1.93, p < 0.001). These differences showed a consistent tendency regardless of pathologic and molecular subtypes.
  
  
  
  The newly proposed M descriptors have prognostic value in patients with stage IV NSCLC.
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Junghoon
authors.initials: J
authors.lastname: Shin
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea. Electronic address: bhumsuk@snu.ac.kr.
authors.forename: Bhumsuk
authors.initials: B
authors.lastname: Keam
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Miso
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Young Sik
authors.initials: YS
authors.lastname: Park
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Tae Min
authors.initials: TM
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Dong-Wan
authors.initials: DW
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Young Whan
authors.initials: YW
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Dae Seog
authors.initials: DS
authors.lastname: Heo
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000556:secondary* / Q000628:therapy; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000556:secondary* / Q000628:therapy; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000556:secondary* / Q000628:therapy; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D014057:Tomography, X-Ray Computed
keywords: External validation; NSCLC; Prognosis; TNM staging