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Abstract

To the Editor: We thank Dr. Lopez-Encuentra et al for their thoughtful and insightful comments. As described in the “Materials and Methods” section, we included only stage I (T1–2N0M0) non-small cell lung cancer patients whose TNM codes were completely recorded in the California Cancer Registry. The T descriptors of all the patients in the study were coded by one of the three extent of disease (EOD) codes: 10, 20, or 40 with no overlap or missing codes indicating excellent internal consistency. The EOD codes and N descriptors were generally abstracted from pathology and/or radiology reports so they can be either pathologically or clinically staged. This limitation was discussed in the article. The Surveillance, Epidemiology, and End Results EOD codes are hierarchically arranged so if a tumor contains both EOD-20 (mainstem bronchus ≥ 2 cm from carina) and EOD-40 (visceral pleura invasion, hilar atelectasis, or obstructive pneumonitis) criteria, only EOD-40 will be coded. We agree with Dr. Lopez-Encuentra et al that we cannot separate the three criteria (visceral pleura invasion, hilar atelectasis, or obstructive pneumonitis) individually, nor can we know how many EOD-40 cases also had EOD-20 criteria, and this is a study limitation. However, we demonstrated that T descriptors coded as T2 due to EOD-20 criteria alone (mainstem bronchus ≥ 2 cm from carina) are infrequent (5.7%). One of our major conclusions is that for tumors ≤ 3 cm but are coded as T2 due to non–sized-based criteria, the overall survival of these T2 tumors are similar to tumors ≤ 3 cm (T1).1Ou S-HI Zell JA Ziogas A et al.Prognostic significance of the non-size based AJCC T2 descriptors: visceral pleura invasion, hilar atelectasis, or obstructive pneumonitis in stage IB non-small cell lung cancer is dependent on tumor size.Chest. 2008; 133: 552-669Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar The referent in the Cox analysis is T2S (tumor > 3 cm), and here T2p ≤ 3 cm has a hazard ratio of 0.8 (p = 0.0039) and T2p> 3 cm has a hazard ratio of 1.155 (p < 0.0001) [Table 3].1Ou S-HI Zell JA Ziogas A et al.Prognostic significance of the non-size based AJCC T2 descriptors: visceral pleura invasion, hilar atelectasis, or obstructive pneumonitis in stage IB non-small cell lung cancer is dependent on tumor size.Chest. 2008; 133: 552-669Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar We can only conclude that for tumors > 3 cm, T2p> 3 cm is an independent poor prognostic factor. Given that we did not compare T2p ≤ 3 cm to tumors ≤ 3 cm (T1) in the Cox multivariate analysis, we cannot conclude that T2p ≤ 3 cm is an independent favorable prognostic factor for tumors ≤ 3 cm. However, we agree with Dr. Lopez-Encuentra et al that it will be important to determine whether the overall survival and prognostic significance of these non–size-based criteria diverge at tumor size 2 cm or 3 cm as the International Association for the Study of Lung Cancer has subdivided the T1 descriptor into T1a (≤ 2 cm) and T1b (> 2 cm and ≤ 3 cm) in the forthcoming lung cancer TNM staging changes.2Rami-Porta R Ball D Crowey J et al.The IASLC staging project: proposals for the revision of the revision of the T descriptors in the forthcoming (seventh) edition of the TNM classification for lung cancer.J Thorac Oncol. 2007; 2: 593-602Abstract Full Text Full Text PDF PubMed Scopus (611) Google Scholar