61 Outcomes in Surgically Resected T3N0 NSCLC in the Dutch population is no role for routine postoperative radiotherapy for a radically excised pT3N0M0 disease87. Our study has several limitations. The pT3 descriptors were based on the conclusion text of the available pathology reports. No data were available on gross examination or microscopy. This may be the explanation for the 36 excluded cases with uncertainty about the exact pT3 descriptor. Because at least two cases with SCLC and one patient with mesothelioma were registered as NSCLC in the IKNL database, other administrative errors cannot be excluded. Furthermore, the finding that the subtype two or more nodules has a better prognosis may partly reflect the fact that most of these cases represented synchronous double primary adenocarcinomas, with only a minority being true intrapulmonary metastases. Multiple stage I tumors within the same lobe are thought to have a good prognosis, with a reported 5-year OS of 82,4% for patients with multiple synchronous adenocarcinomas88. On the basis of the available database information, we are unable to distinguish between synchronous primaries and isolated lung metastases in our study group. In conclusion, in this population-based study of OS for pT3N0 categories in NSCLC shows that (1) there is limited support for migration of the descriptor tumor diameter larger than 7 cm from category pT3 in the TNM-7 to the category pT4 in the TNM-8, (2) histologic type deserves a role as descriptor in the two or more nodules category, where adenocarcinomas may be migrated to the pT2 and squamous cell carcinomas remain pT3, and (3) a combination of two pT3 descriptors may be migrated to pT4. With the advent of new therapies, the relevance of proper prognostication increases and such findings, as well as ethnic bias, needs to be considered in international studies. 4
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