59 Outcomes in Surgically Resected T3N0 NSCLC in the Dutch population Table 4. Mean 5-Year OS of T3N0 NSCLC and stage IIA and IIIA as in the IASLC Database for the TNM-7 and TNM-8 with comparison to our study, Including histologic subtypes and CIs. (continued) TNM-7 Proposed TNM-8 Current study stage 5 yrs OS stage 5 yrs OS 5 yrs OS 95% CI IIA 57% IIA 65% All mixed IIB 49% IIB 49% 28.7% 18.5%-38.9% AdC n.a. n.a. 28.2% 10.0%-46.4% SqCC n.a. n.a. 38.4% 25.0%-51.9% IIIB 23% IIIB 24% OS, overall survival; IASLC, International Association for the Study of Lung Cancer; TNM-7, seventh edition of the TNM classification; TNM-8, eighth edition of the TNM classification; CI, confidence interval; AdC, adenocarcinoma; SqCC, squamous cell carcinoma; na, not available Discussion In this retrospective population-based study we demonstrated that the subgroup of patients with the T3 descriptor two or more nodules had a better 5-years OS (62.8%) than did patients with the other T3 subtypes. This observation is conditional on histologic type, a factor not considered in the TNM classification. Adenocarcinomas of the subtype two nodules or more showed a 5-years OS of 65.1%, comparable to that for TNM-8 stage IIA tumors (65%). On the basis on the IASLC data, the subtypes pleural invasion and two or more nodules remain allocated to the pT3 category 16,79. Our data on adenocarcinomas in the two nodules or more subtype may be an argument to transfer this subgroup to pT2. On the contrary, for squamous cell carcinoma the 5-years OS rate (47.2%) was similar to the survival of the pT3N0 two or more nodules subtype of the IASLC database (49%) 16. In this context, our data provide a strong argument for histology to become a descriptor for pT staging. For the T3 descriptors tumor diameter larger than 7 cm and pleural invasion, 5-years OS of 47.2% and 45.3% were found, respectively, which are in between the 5-years survivals reported for stages IIB and IIIA in the TNM-8 (56% and 41%; Table 4). However, in the IASLC database, the descriptor tumor diameter larger than 7 cm was classified as having the same prognosis as the pT4 category (stage IIIA), which was the argument for upgrading. One could argue that based on our data cases with pleural invasion should be migrated to the pT4 category, or alternatively, that cases with a tumor diameter larger than 7 cm or pleural invasion should both remain in the pT3 category. Our finding that tumors with a diameter larger than 7 cm were more often located in the lower lobes, whereas at least two-thirds of the other subtypes were found in the upper lobes, is not easy to explain. A speculation may be that the lung volumes in the lower lobes are larger than those in the upper lobes 81. In this context, tumors may 4
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