Role of FDG PET/CT in the Eighth Edition of TNM Staging of Non–Small Cell Lung Cancer

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

This article proposes codes for the primary tumor categories of adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) and a uniform way to measure tumor size in part-solid tumors for the eighth edition of the tumor, node, and metastasis classification of lung cancer. In 2011, new entities of AIS, MIA, and lepidic predominant adenocarcinoma were defined, and they were later incorporated into the 2015 World Health Organization classification of lung cancer. To fit these entities into the T component of the staging system, the Tis category is proposed for AIS, with Tis (AIS) specified if it is to be distinguished from squamous cell carcinoma in situ (SCIS), which is to be designated Tis (SCIS). We also propose that MIA be classified as T1mi. Furthermore, the use of the invasive size for T descriptor size follows a recommendation made in three editions of the Union for International Cancer Control tumor, node, and metastasis supplement since 2003. For tumor size, the greatest dimension should be reported both clinically and pathologically. In nonmucinous lung adenocarcinomas, the computed tomography (CT) findings of ground glass versus solid opacities tend to correspond respectively to lepidic versus invasive patterns seen pathologically. However, this correlation is not absolute; so when CT features suggest nonmucinous AIS, MIA, and lepidic predominant adenocarcinoma, the suspected diagnosis and clinical staging should be regarded as a preliminary assessment that is subject to revision after pathologic evaluation of resected specimens. The ability to predict invasive versus noninvasive size on the basis of solid versus ground glass components is not applicable to mucinous AIS, MIA, or invasive mucinous adenocarcinomas because they generally show solid nodules or consolidation on CT.

The present retrospective study was performed to evaluate the clinicopathological characteristics associated with distant metastasis from non-small-cell lung cancer (NSCLC). The records of NSCLC patients with metastasis at the time of diagnosis between 1999 and 2012 were reviewed. Of the consecutive 1,542 NSCLC patients diagnosed during the study period, 729 (47.3%) patients presented with distant metastasis. Among those 729 metastatic NSCLC patients, 250 (34.3%), 234 (32.1%), 207 (28.4%), 122 (16.7%), 98 (13.4%) and 69 (9.5%) had bone, lung, brain, adrenal gland, liver and extrathoracic lymph node metastasis, respectively. In a multivariate analysis using the Cox proportional hazards model, liver and adrenal gland metastases were unfavorable prognostic factors. However, brain and bone metastases were not statistically significant prognostic factors. Using a logistic regression analysis, metastasis to the adrenal glands and the presence of pleural and/or pericardial fluid effusion were correlated with a poor performance status. Therefore, when planning the treatment of NSCLC patients, particularly those with liver and adrenal gland metastases, we should take into consideration information regarding these unfavorable organ metastases.