Small Cell Lung Cancer Diagnosis

Staging Systems

Several staging systems have been proposed for small cell lung cancer (SCLC). These staging systems include the following:

• American Joint Committee on Cancer (AJCC) Tumor, Node, and Metastasis (TNM).[1]
• Veterans Administration Lung Study Group (VALG).[2]
• International Association for the Study of Lung Cancer (IASLC).[3]

Limited-Stage Disease

No universally accepted definition of this term is available. Limited-stage disease (LD) SCLC is confined to the hemithorax of origin, the mediastinum, or the supraclavicular nodes, which can be encompassed within a tolerable radiation therapy port.

Patients with pleural effusion, massive pulmonary tumor, and contralateral supraclavicular nodes have been both included within and excluded from LD by various groups.

Extensive-Stage Disease

Extensive-stage disease (ED) SCLC has spread beyond the supraclavicular areas and is too widespread to be included within the definition of LD. Patients with distant metastases (M1) are always considered to have ED.[3,4]

IASLC-AJCC TNM Staging System

The AJCC TNM defines LD as any T, except for T3-4, due to multiple lung nodules that do not fit in a tolerable radiation field, any N, and M0.[1] This corresponds to TNM stages I to IIIB. Extensive disease is TNM stage IV with distant metastases (M1) including malignant pleural effusions.[3,4]

The IASLC conducted an analysis of clinical TNM staging for SCLC using the sixth edition of the AJCC TNM staging system for lung cancer. Survivals for patients with clinical stages I and II disease are significantly different from those for patients with stage III disease with N2 or N3 involvement.[3] Patients with pleural effusion have an intermediate prognosis between LD and ED with hematogenous metastases and will be classified as having M1 disease (or ED). Application of the TNM system will not change how patients are managed; however, the analysis suggests that, in the context of clinical trials in LD, accurate TNM staging and stratification may be important.[3]

Staging Evaluation

Staging procedures for SCLC are important to distinguish patients with disease limited to their thorax from those with distant metastases. At the time of initial diagnosis, approximately two-thirds of patients with SCLC have clinical evidence of metastases; most of the remaining patients have clinical evidence of extensive nodal involvement in the hilar, mediastinal, and sometimes supraclavicular regions.

Determining the stage of cancer allows an assessment of prognosis and a determination of treatment, particularly when chest radiation therapy or surgical excision is added to chemotherapy for patients with LD. If ED is confirmed, further evaluation should be individualized according to the signs and symptoms unique to the individual patient. Standard staging procedures include the following:

• A thorough physical examination.
• Routine blood counts and serum chemistries.
• Chest and upper abdominal computed tomography (CT) scanning.
• A radionuclide bone scan.
• A brain magnetic resonance imaging scan or CT scan.
• Bone marrow aspirate or biopsy in selected patients in which treatment would change based on the results.

The role of positron emission tomography (PET) is still under study. SCLC is fluorodeoxyglucose (FDG) avid at the primary site and at metastatic sites. PET may be used in staging patients with SCLC who are potential candidates for the addition of thoracic radiation therapy to chemotherapy, as PET may lead to upstaging or downstaging of patients and to alteration of radiation fields resulting from the identification of additional sites of nodal metastases.

Evidence (FDG-PET):

1. In a study of 120 patients with LD SCLC or ED SCLC, ten patients were upstaged and three patients were downstaged.[5] PET was more sensitive and specific than CT scans for nonbrain distant metastases.
2. In a small series of 24 patients with LD by conventional staging, two patients were upstaged to ED.[2] Unsuspected nodal metastases were documented in 25% of patients, which altered the radiation plan in these patients. At this time, sensitivity, specificity, and positive- or negative-predictive value of PET scanning and its enhancement of staging accuracy are uncertain.

References

1. Lung. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 253-70.
2. Bradley JD, Dehdashti F, Mintun MA, et al.: Positron emission tomography in limited-stage small-cell lung cancer: a prospective study. J Clin Oncol 22 (16): 3248-54, 2004. [PUBMED Abstract]
3. Shepherd FA, Crowley J, Van Houtte P, et al.: The International Association for the Study of Lung Cancer lung cancer staging project: proposals regarding the clinical staging of small cell lung cancer in the forthcoming (seventh) edition of the tumor, node, metastasis classification for lung cancer. J Thorac Oncol 2 (12): 1067-77, 2007. [PUBMED Abstract]
4. Ihde D, Souhami B, Comis R, et al.: Small cell lung cancer. Lung Cancer 17 (Suppl 1): S19-21, 1997. [PUBMED Abstract]
5. Brink I, Schumacher T, Mix M, et al.: Impact of [18F]FDG-PET on the primary staging of small-cell lung cancer. Eur J Nucl Med Mol Imaging 31 (12): 1614-20, 2004. [PUBMED Abstract]

Source:

https://www.cancer.gov/types/lung/hp/small-cell-lung-treatment-pdq#secti…