Frontal Chest X-Ray demonstrating a small visible tumour confined to the left upper lobe of the lung with no mediastinum (the membranous partition between the lungs) involvement and no signs of supraclavicular ipsilateral lymph nodes involved. Findings: Small-Cell Lung Carcinoma Limited Stage Disease.
In clinical practice and research trials small-cell carcinoma is divided into two main classifications which are:- limited and extensive disease. These stages were devised by the Veterans’ Administration Lung Study Group (VALSG) and revised in 1989 by the International Association for the Study of Lung Cancer (IASLC)(1)
Limited stage disease: This is the allocated stage for small-cell lung cancer if the tumour is confined to the hemi-thorax of origin (basically one side of the chest), the mediastinum (the membranous partition between the lungs) or the supraclavicular ipsilateral lymph nodes (the supraclavicular lymph nodes are located just above the clavicle or collar bone near the hollow of the neck and ipsilateral means on the affected or same side as the presenting tumour). Approximately 30% of small-cell lung tumours are found at this stage as seen in Image 1.(2)
Frontal Chest X-Ray. A large mass is visible in the left lung with an area of increased density (showing as an opacity or lightened area) that extends to the upper lung. There is a lower lung nodule noted on the right lung (purple circle) that is suggestive of a secondary tumour indicating metastatic spread to the opposite lung. Increased opacity on the right lymph node of the throat (paratracheal) indicates lymphadenopathy (lymph node invlolvement). In addition there is a small left pleural effusion (pleural effusion is an execess of fluid that gathers in the pleural cavity). Findings: Small-cell lung carcinoma Extended Disease.
Extensive stage disease: This is the allocated stage for small-cell lung cancer if the tumours have spread beyond the hemi-thorax, the mediastinum or the supraclavicular lymph nodes of the affected side. Of the total number of cases of small-cell lung cancer it is estimated that around two out of three patients already have extensive disease at the time of diagnosis. This is due in part to the fact that small-cell lung cancer is an aggressive disease and the tumour or tumours grow and metastasise rapidly, so often by the time that symptoms have manifested the cancer has already spread. The most common sites of metastatic spread in lung cancer include the other lung, the adrenal gland or glands, bone, brain and liver. Patients that are diagnosed with extensive-stage disease are usually treated with chemotherapy and possibly radiation therapy as well.
Small-Cell Lung Carcinoma
Small-cell lung cancer is so named after the appearance of the cells; they are undifferentiated and smaller than normal cells consisting mainly of the nucleus with hardly any cytoplasm, for this reason small-cell lung cancer is also sometimes called ‘oat cell carcinoma’. Small-cell carcinomas are thought to originate from neuroendocrine cells that can be found in the bronchial mucosa. According to studies around 90 – 95% of small-cell lung cancers are centrally located and usually arise in a main bronchus or a lobar bronchi (a subdivision of the bronchus) and appear as hilar or perihilar growths. The remaining 5 – 10% of small-cell lung cancers present in a peripheral position of the lung.(3) Small-cell lung cancers tend to be aggressive, so even though the cells are small the tumours grow rapidly and are more widely metastatic (have a greater tendency to spread to other parts of the body) than non-small cell lung cancers.(4) The most common sites of metastatic spread in lung cancer include the other lung, the adrenal gland or glands, bone, brain and liver.
1. Sørensen M. [et al.] ‘Small-cell lung cancer: ESMO Clinical Practice’ Annals of Oncology 21: v120–v125, 2010 clinical practice guidelines doi:10.1093/annonc/mdq172
2. Murray N, Coy P, Pater JL, et al.: Importance of timing for thoracic irradiation in the combined modality treatment of limited-stage small-cell lung cancer. The National Cancer Institute of Canada Clinical Trials Group. J Clin Oncol 11 (2): 336-44, 1993. [PUBMED Abstract]
3. Titulaer MJ, Verschuuren JJ (2008). “Lambert-Eaton myasthenic syndrome: tumor versus nontumor forms”. Ann. N. Y. Acad. Sci. 1132: 129–34.
4. Gupta P (December 2004). “The Golden S sign”. Radiology 233 (3): 790–1. doi:10.1148/radiol.2333021407. PMID 15564409.