Local failure in patients treated with radiotherapy and multidrug chemotherapy for small cell lung cancer

Fifty-three patients with small cell carcinoma of the lung were treated with chemotherapy and radiotherapy, 40 Gy in the chest tumour. Intrathoracic failure occurred in 89% of the cases with extensive disease and in 60% of those with limited disease. Since 86% of all failures were localized within the target volume, one can conclude that in most cases the radiation dose was too low for eradication of the tumour. The treatment technique resulted in dose inhomogeneities of more than +/- 5% in 45% of the cases. The high local failure rate might indicate the need of improved radiotherapy, in the first place higher radiation dose. However, 82% of the patients with limited disease and local failure and 50% of those without local failure also developed distant metastases. This might indicate that the curative potential of improved thoracic radiotherapy probably is limited. Besides, lethal treatment toxicity affected particularly patients in whom local cure had been achieved, indicating the difficulty of increasing the treatment intensity without increasing the lethal toxicity in potentially curable cases.