Purpose: To assess the impact of age on the delivery, tolerance, and efficacy of thoracic irradiation (TI) for limited small cell lung cancer (L-SCLC).
Methods and materials: This is a retrospective review of data from 608 patients 80 years or less with L-SCLC, who participated in two previously reported randomized trials (BR3 and BR.6) of the National Cancer Institute of Canada. All patients received the same chemotherapy, consisting of cyclophosphamide, doxorubicin, vincristine (CAV), and etoposide cisplatin (EP) delivered either in sequential or alternating sequence. In BR.3, TI was given after chemotherapy with randomization to 25 Gy in 10 fractions or 37.5 Gy in 15 fractions. In BR.6, TI (40 Gy in 15 fractions) was given concurrently with EP with randomization to either the early (with cycle 2, week 4) or late (with cycle 6, week 16) arm.
Results: A total of 665 patients entered these two trials. Of these, 608 patients were eligible for analysis, 300 in BR.3 and 308 in BR.6. Five hundred and twenty patients were under age 70 and 88 patients were 70 years or older. Baseline characteristics between the two groups were comparable. In BR3, 179 patients (60%) participated in radiotherapy randomization (61% young, 52% elderly), and 176 patients actually received TI. In BR.6, randomization occurred at study entry for all patients, and 282 (91.6%) patients received TI (92% young, 88% elderly). More patients of both age groups randomized to receive late TI did not receive TI (13% and 14%) than those randomized to the early TI arm (3%) of BR.6. We could identify no tendency to reduce field sizes to minimize toxicity in either age group at higher doses of TI. Once TI was started, there was no difference between the two age groups with regards to the proportion of patients who completed TI, although elderly patients were less likely to complete high dose TI. Of those who completed TI, there was no difference in the time to complete TI, mean dose delivered or in the incidence of acute and late TI-related toxicities. No statistical difference in response rate, local relapse rate, or overall survival was seen between young and older age groups.
Conclusion: In summary, in the dose range examined, age does not appear to impact on the delivery, tolerance or efficacy of TI in the combined modality management of L-SCLC. Potentially curative combined modality treatment should not be withheld on the basis of age.