IASLC Staging Committee Article
The IASLC Lung Cancer Staging Project: Proposals for the Revisions of the T Descriptors in the Forthcoming Eighth Edition of the TNM Classification for Lung Cancer

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Introduction:

An international database was collected to inform the 8th edition of the anatomic classification of lung cancer. The present analyses concern its primary tumor (T) component.

Methods:

From 1999 to 2010, 77,156 evaluable patients, 70,967 with non–small-cell lung cancer, were collected; and 33,115 had either a clinical or a pathological classification, known tumor size, sufficient T information, and no metastases. Survival was measured from date of diagnosis or surgery for clinically and pathologically staged tumors. Tumor-size cutpoints were evaluated by the running log-rank statistics. T descriptors were evaluated in a multivariate Cox regression analysis adjusted for age, gender, histological type, and geographic region.

Results:

The 3-cm cutpoint significantly separates T1 from T2. From 1 to 5 cm, each centimeter separates tumors of significantly different prognosis. Prognosis of tumors greater than 5 cm but less than or equal to 7 cm is equivalent to T3, and that of those greater than 7 cm to T4. Bronchial involvement less than 2 cm from carina, but without involving it, and total atelectasis/pneumonitis have a T2 prognosis. Involvement of the diaphragm has a T4 prognosis. Invasion of the mediastinal pleura is a descriptor seldom used.

Conclusions:

Recommended changes are as follows: to subclassify T1 into T1a (⩽1 cm), T1b (>1 to ⩽2 cm), and T1c (>2 to ⩽3 cm); to subclassify T2 into T2a (>3 to ⩽4 cm) and T2b (>4 to ⩽5 cm); to reclassify tumors greater than 5 to less than or equal to 7 cm as T3; to reclassify tumors greater than 7 cm as T4; to group involvement of main bronchus as T2 regardless of distance from carina; to group partial and total atelectasis/pneumonitis as T2; to reclassify diaphragm invasion as T4; and to delete mediastinal pleura invasion as a T descriptor.

Key Words

Lung cancer
Lung cancer staging
T component
T descriptors
TNM classification
Tumor size

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Disclosure: David Ball has declared ongoing board memberships of Lilly Oncology, Astra Zeneca and Boehring-Ingelheim. John Crowley has declared that his work is fundded by the International Association for the Study of Lung Cancer (IASLC) and has received grants and support to travel from the IASLC. Vanessa Bolejack has declared that her work is currently funded by the International Association for the Study of Lung Cancer (IASLC) and that she has received grants and support to travel and to write and review articles from the IASLC. William D. Travis has declared that he is a current member of the Board of the International Association for the Study of Lung Cancer, but this activity has no financial implications. Yi-Long Wu has declared he currently receives payment for lectures from Roche.