The IASLC Mesothelioma Staging Project: Proposals for Revisions of the T Descriptors in the Forthcoming Eighth Edition of the TNM Classification for Pleural Mesothelioma.
The current T component for malignant pleural mesothelioma (MPM) has been predominantly informed by surgical data sets and consensus. The International Association for the Study of Lung Cancer undertook revision of the seventh edition of the staging system for MPM with the goal of developing recommendations for the eighth edition.



Data elements including detailed T descriptors were developed by consensus. Tumor thickness at three pleural levels was also recorded. An electronic data capture system was established to facilitate data submission.



A total of 3519 cases were submitted to the database. Of those eligible for T-component analysis, 509 cases had only clinical staging, 836 cases had only surgical staging, and 642 cases had both available. Survival was examined for T categories according to the current seventh edition staging system. There was clear separation between all clinically staged categories except T1a versus T1b (hazard ratio = 0.99, p = 0.95) and T3 versus T4 (hazard ratio = 1.22, p = 0.09), although the numbers of T4 cases were small. Pathological staging failed to demonstrate a survival difference between adjacent categories with the exception of T3 versus T4. Performance improved with collapse of T1a and T1b into a single T1 category; no current descriptors were shifted or eliminated. Tumor thickness and nodular or rindlike morphology were significantly associated with survival.



A recommendation to collapse both clinical and pathological T1a and T1b into a T1 classification will be made for the eighth edition staging system. Simple measurement of pleural thickness has prognostic significance and should be examined further with a view to incorporation into future staging.
National Centre for Asbestos Related Diseases, School of Medicine and Pharmacology, University of Western Australia, Crawley, Western Australia, Australia; Department of Medical Oncology, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia. Electronic address: anna.nowak@uwa.edu.au.
Anna K
AK
Nowak
Cancer Research And Biostatistics, Seattle, Washington.
Kari
K
Chansky
M. D. Anderson Cancer Center, Houston, Texas.
David C
DC
Rice
Department of Cardiothoracic Surgery, New York University Langone Medical Center, New York, New York.
Harvey I
HI
Pass
Department of Medicine, Section of Hematology/Oncology, University of Chicago, Chicago, Illinois.
Hedy L
HL
Kindler
Cancer Research And Biostatistics, Seattle, Washington.
Lynn
L
Shemanski
Department of Thoracic Surgery, Guy's Hospital, London, United Kingdom.
Andrea
A
Billé
Department of Thoracic Oncology, Papworth Hospital National Health Service Foundation Trust, Cambridge, United Kingdom.
Robert C
RC
Rintoul
Department of Thoracic Surgery, Marmara University Faculty of Medicine, Istanbul, Turkey.
Hasan F
HF
Batirel
Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota.
Charles F
CF
Thomas
Department of Thoracic Surgery, University of Maryland Cancer Center, Baltimore, Maryland.
Joseph
J
Friedberg
Medical Oncology Department, Vall d'Hebron Institute of Oncology, Vall d'Hebron University Hospital, Barcelona, Spain.
Susana
S
Cedres
Division of Thoracic Surgery, Toronto General Hospital, and Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada.
Marc
M
de Perrot
Thoracic Surgery, Memorial Sloan Kettering Cancer Center, New York, New York.
Valerie W
VW
Rusch
D006801:Humans; D008175:Lung Neoplasms / Q000145:classification* / Q000473:pathology; D008654:Mesothelioma / Q000145:classification* / Q000473:pathology; D000086002:Mesothelioma, Malignant; D009367:Neoplasm Staging / Q000145:classification*; D010997:Pleural Neoplasms / Q000145:classification* / Q000473:pathology
Mesothelioma; Prospective; Staging; T component