Small Cell Lung Cancer Treatment Professional Information

Cellular Classification

Review of pathologic material by an experienced lung cancer pathologist is important prior to initiating treatment of any patient with small cell lung cancer. The intermediate subtype of small cell carcinoma and the more readily recognized lymphocyte-like or "oat cell" subtype are equally responsive to treatment.

The current classification of subtypes of small cell lung cancer are:¹

• small cell carcinoma
  
• mixed small cell/large cell carcinoma
  
• combined small cell carcinoma (small cell lung cancer combined with neoplastic squamous and/or glandular components)

There is increasing evidence that light microscopy has some limitations as a means of classifying bronchogenic carcinomas, particularly small cell carcinomas. Electron microscopy, which can detect neuroendocrine granules, may help to differentiate between small cell and non-small cell cancers.²

Neuroendocrine carcinomas of the lung represent a spectrum of disease. At one extreme is small cell lung cancer, which has a poor prognosis. At the other extreme are bronchial carcinoids, with an excellent prognosis after surgical excision.³ Between these extremes is an unusual entity called well-differentiated neuroendocrine carcinoma of the lung.⁴ It has been referred to as malignant carcinoid, metastasizing bronchial adenoma, pleomorphic carcinoid, nonbenign carcinoid tumor, and atypical carcinoid. Like small cell lung cancer, it occurs primarily in cigarette smokers, but it metastasizes less frequently. The 5-year survival rate is greater than 50% in some series, and surgical cure appears possible in most stage I patients. Careful diagnosis is important, however, since the differential pathologic diagnosis from small cell lung cancer may be difficult.

References:

1. Hirsch FR, Matthews MJ, Aisner S, et al.: Histopathologic classification of small cell lung cancer: changing concepts and terminology. Cancer 62(5): 973-977, 1988.
2. Mooi WJ, Van Zandwijk N, Dingemans KP, et al.: The "Grey Area" between small cell and non-small cell lung carcinomas: light and electron microscopy versus clinical data in 14 cases. Journal of Pathology 149(1): 49-54, 1986.
3. Harpole DH, Feldman JM, Buchanan S, et al.: Bronchial carcinoid tumors: a retrospective analysis of 126 patients. Annals of Thoracic Surgery 54(1): 50-55, 1992.
4. Lequaglie C, Patriarca C, Cataldo I, et al.: Prognosis of resected well-differentiated neuroendocrine carcinoma of the lung. Chest 100(4): 1053-1056, 1991.

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