Evaluation of distant metastasis other than the brain
Numerous nonrandomized, prospective, and retrospective studies have demonstrated that FDG-PET scanning seems to offer diagnostic advantages over conventional imaging in staging distant metastatic disease; however, standard FDG-PET scans have limitations. FDG-PET scans may not extend below the pelvis and may not detect bone metastases in the long bones of the lower extremities. Because the metabolic tracer used in FDG-PET scanning accumulates in the brain and urinary tract, FDG-PET scanning is not reliable for detection of metastases in these sites.
The Revised International System for Staging Lung Cancer
The Revised International System for Staging Lung Cancer, based on information from a clinical database of more than 5,000 patients, was adopted in 2010 by the American Joint Committee on Cancer (AJCC) and the Union Internationale Contre le Cancer.[18,19] These revisions provide greater prognostic specificity for patient groups; however, the correlation between stage and prognosis predates the widespread availability of PET imaging.
Summary of Changes
This staging system is now recommended for the classification of both NSCLC and small cell lung carcinomas and for carcinoid tumors of the lung.
The T (primary tumor) classifications have been redefined as follows:
- T1 has been subclassified into T1a (≤2 cm in size) and T1b (>2-3 cm in size).
- T2 has been subclassified into T2a (>3-5 cm in size) and T2b (>5-7 cm in size).
- T2 (>7 cm in size) has been reclassified as T3.
- Multiple tumor nodules in the same lobe have been reclassified from T4 to T3.
- Multiple tumor nodules in the same lung but a different lobe have been reclassified from M1 to T4.
No changes have been made to the N (regional lymph nodes) classification. However, a new international lymph node map defining the anatomical boundaries for lymph node stations has been developed.
The M (distant metastasis) classifications have been redefined as follows:
- M1 has been subdivided into M1a and M1b.
- Malignant pleural and pericardial effusions have been reclassified from T4 to M1a.
- Separate tumor nodules in the contralateral lung are considered M1a.
- M1b designates distant metastasis.