Purpose: To determine if there is an effect of thoracic radiotherapy dose on survival in patients with non small cell lung cancer localised to the primary site and regional lymph nodes.
Methods and materials: Nine hundred and forty-one previously untreated patients with limited non small cell lung cancer presenting at Peter MacCallum Cancer Institute during 1984-1989 inclusive, were planned to receive radiotherapy using one of three schedules: 20 Gy in five fractions; 30 or 36 Gy in 10 or 12 fractions; and 60 Gy in 30 fractions. The survival of patients in each of the groups was analysed to determine if there was an effect of dose on survival, before and after adjusting for the major prognostic factors, performance status and weight loss.
Results: The survival of patients planned to receive 60 Gy was significantly better than for patients planned to receive lower doses (p < 0.0001) with median survival increasing from 6.1 to 9.2 and 14.5 months for the 20 Gy, 30 or 36 Gy and 60 Gy groups, respectively. After adjusting for the effect of performance status and weight loss, death rates relative to the 20 Gy group were 79% (95% confidence interval: 67-93%) for patients planned to receive 30 or 36 Gy and 53% (95% confidence interval: 44-65%) for patients planned to receive 60 Gy.
Conclusion: These data support the hypothesis that the increased survival in patients with limited non small cell lung cancer treated with higher dose radiotherapy is not due purely to patient selection.