Reasons for Separate Classification
- Doubling Time:
- Small cell carcinoma has a doubling time which is several fold higher than
non-small carcinoma. This results in an increased growth fraction of the tumor which
causes a significantly increased metastatic potential. Thus, patients with small cell
carcinoma are more likely to present with systemic disease.
- Paraneoplastic Syndromes:
- Small cell carcinomas are much more likely to produce paraneoplastic syndromes
than other types of lung carcinoma. This is felt to be due to the biochemical properties
of the cells.
- The therapy for small cell carcinoma is different. Small cell has shown an
increased sensitivity to chemotherapy over other types of bronchogenic carcinoma. In
non-small cell carcinoma, surgical intervention is the primary form of treatment.