The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org N Descriptor The eighth edition makes no changes from the previous edition with regard to metastatic nodal disease. The N stage is based on location of metastatic nodes. Increasing number of involved nodal stations negatively affects prognosis [5]. A lymph node size threshold of >10 mm in axial short axis diameter is considered abnormal. The prevalence of metastatic lung cancer in thoracic lymph nodes is 30% for nodes that are 10 to 15 mm in short axis diameter and 67% for nodes >15 mm [7]. Axillary lymph node metastasis occurs in 0.75% of lung cancers [8]. It is not included in the N descriptor but is considered metastatic M1 disease. Nx indicates that lymph nodes cannot be assessed [5]. N0 is consistent with lack of regional node involvement [5]. N1 includes ipsilateral peribronchial, hilar or intrapulmonary lymph node(s) [5]. N2 describes ipsilateral mediastinal or subcarinal lymph node(s) [5]. N3 includes contralateral mediastinal or hilar lymph node(s) and any supraclavicular or scalene node on either side [5]. M Descriptor The presence of metastatic lung cancer lesions constitutes stage IV disease. Many patients with NSCLC present with metastatic disease [9], and the treatment of stage IV cancers depends on the location and number of lesions. M0 disease is consistent with no distant metastases [5]. The M1 classification is subdivided into three categories: M1a includes satellite nodule(s) in the contralateral lung and cytology proven malignant pleural or pericardial effusion [5]. M1b indicates a single extrathoracic metastasis.
Noninvasive Clinical Staging of Primary Lung Cancer PCAs. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: publications@acr.org N Descriptor The eighth edition makes no changes from the previous edition with regard to metastatic nodal disease. The N stage is based on location of metastatic nodes. Increasing number of involved nodal stations negatively affects prognosis [5]. A lymph node size threshold of >10 mm in axial short axis diameter is considered abnormal. The prevalence of metastatic lung cancer in thoracic lymph nodes is 30% for nodes that are 10 to 15 mm in short axis diameter and 67% for nodes >15 mm [7]. Axillary lymph node metastasis occurs in 0.75% of lung cancers [8]. It is not included in the N descriptor but is considered metastatic M1 disease. Nx indicates that lymph nodes cannot be assessed [5]. N0 is consistent with lack of regional node involvement [5]. N1 includes ipsilateral peribronchial, hilar or intrapulmonary lymph node(s) [5]. N2 describes ipsilateral mediastinal or subcarinal lymph node(s) [5]. N3 includes contralateral mediastinal or hilar lymph node(s) and any supraclavicular or scalene node on either side [5]. M Descriptor The presence of metastatic lung cancer lesions constitutes stage IV disease. Many patients with NSCLC present with metastatic disease [9], and the treatment of stage IV cancers depends on the location and number of lesions. M0 disease is consistent with no distant metastases [5]. The M1 classification is subdivided into three categories: M1a includes satellite nodule(s) in the contralateral lung and cytology proven malignant pleural or pericardial effusion [5]. M1b indicates a single extrathoracic metastasis.