Impact of tumor control on survival in carcinoma of the lung treated with irradiation

Abstract

The long-term results in tumor response, intrathoracic tumor control and survival are reported in patients with medically inoperable or unresectable non-oat cell and small cell carcinoma of the lung. In 376 patients with stages T1-3, NO-2 carcinoma of the lung tumors, accessioned to a Radiation Therapy Oncology Group (RTOG) randomized study to evaluate different doses of irradiation, a higher complete response rate (24%), intrathoracic tumor control (67%) and three year survival (15%) was observed with 6000 cGy, compared with lower doses of irradiation (4000 or 5000 cGy). Increased survival was noted in patients with complete tumor response. Three year survival in complete responders was 23%, in partial responders, 10%, and in patients with stable disease, 5%. Patients treated with 6000 cGy had an overall intrathoracic failure rate of 33% at 3 years, compared with 42% for those treated with 5000 cGy, 44% for patients receiving 4000 cGy with split course, and 52% for those treated with 4000 cGy continuous course (p = 0.02). Patients surviving 6 or 12 months exhibited a statistically significant increased survival when the intrathoracic tumor was controlled. Patients treated with 5000-6000 cGy, showing tumor control, had a three year survival of 22%, versus 10%, if they had intrathoracic failure (p = 0.05). In patients treated with 4000 cGy (split or continuous), the respective survival was 20% and 10%, if the intrathoracic tumor was controlled (p = 0.001). In patients surviving 12 months after treatment with 5000-6000 cGy, on whom the intrathoracic tumor was controlled, the median survival was 29 months, in contrast to 18 months, if they developed intrathoracic failure (p = 0.05). In patients treated with 4000 cGy, the median survival was 23 months with control and 18 months without control of the intrathoracic tumor [corrected] (p = 0.008). In another RTOG study for patients with more advanced tumors (T4 or N3), those with local tumor control at 12 months had a three year survival rate of 25%, compared with 5% for those with thoracic failures. These differences are statistically significant (p = 0.006). Higher doses of irradiation yield a greater proportion of complete response, higher intrathoracic tumor control and better survival in non-oat cell medically inoperable or unresectable carcinoma of the lung.(ABSTRACT TRUNCATED AT 400 WORDS)