Cranial irradiation for preventing brain metastases of small cell lung cancer in patients in complete remission
Abstract
Background
Prophylactic cranial irradiation halves the rate of brain metastases in patients with small cell lung cancer. Individual randomized trials conducted on patients in complete remission were unable to clarify whether this treatment improves survival.
Objectives
This study aims to test whether prophylactic cranial irradiation prolongs survival of patients with small cell lung cancer in complete remission.
Search methods
Published and unpublished trials were eligible. Electronic databases (Medline, Cancerlit, Excerpta Medica, Biosis from 1965 to 1998), reference lists of trial publications, review articles and relevant books were used to identify potentially eligible trials. The search was also guided by discussions with investigators and experts, and the examination of meeting proceedings and of the Physician Data Query clinical trial registry.
Selection criteria
Randomized trials comparing prophylactic cranial irradiation with no prophylactic cranial irradiation in patients with small cell lung cancer in complete remission.
Data collection and analysis
Meta‐analysis based on updated individual data. The main endpoint was survival.
Main results
Seven trials with a total of 987 participants were included. The relative risk of death in the treatment group compared to the control group was 0.84 (95% confidence interval=0.73 to 0.97, P=0.01), corresponding to a 5.4 percent increase in the 3‐year survival rate (from 15.3 percent in the control group to 20.7 percent in the treatment group). Prophylactic cranial irradiation also increased disease‐free survival (relative risk=0.75, 95% confidence interval=0.65 to 0.86, P<0.001) and decreased the risk of brain metastases (relative risk=0.46, 95% confidence interval=0.38 to 0.57, P<0.001). Increasing doses of irradiation decreased the risk of brain metastases when four groups (8 Gy, 24‐25 Gy, 30 Gy, 36‐40 Gy) were analyzed [trend test, P=0.02], but the effect on survival did not differ significantly according to the dose. We found a trend (P=0.01) for a decrease in the brain metastasis risk in favour of earlier administration of cranial irradiation after the initiation of induction treatment.
Authors' conclusions
Prophylactic cranial irradiation significantly improves survival and disease‐free survival for patients with small cell lung cancer in complete remission. Further clinical trials are needed to confirm the potential greater benefit on brain metastasis rate suggested when cranial irradiation is given earlier or at higher doses.
Plain language summary
Prophylactic cranial irradiation improves survival rate of patients with small‐cell lung cancer in complete remission
Small‐cell lung cancer accounts for 20‐25% of lung cancer. Treatment with chemotherapy and thoracic radiotherapy yields complete response rates of 50‐85%. But, due to relapses, only 15% of patients who achieved complete response survived at 3 years since treatment. Tumour spread to brain (metastasis) is one of the main types of relapse, occurring in more than 50% of patients. Several clinical trials showed that prophylactic cranial irradiation (X‐ray treatment of the brain for preventing brain metastasis) halves the rate of brain metastasis but they did not show whether this treatment can help people to live longer. This review found that prophylactic cranial irradiation given to patients in complete remission after initial treatment improves survival. At 3 years since treatment 20.7% of patients who received prophylactic cranial irradiation survived, compared to 15.3% for those who did not received this irradiation. Prophylactic cranial irradiation should now be considered part of the standard treatment of patients with small‐cell lung cancer in complete remission.
