Efficacy
The evidence supporting this protocol is provided by a phase III multicentre international randomised trial involving 286 patients comparing PCI post chemotherapy with no PCI in patients with extensive small cell lung cancer (SCLC).r Between 2001 and 2006, 143 patients were randomised to receive PCI and 143 patients were randomised to receive no PCI after initial chemotherapy. The primary end point was symptomatic brain metastases and secondary end points were survival, toxicity and costs. At one year the symptomatic brain metastases and overall survival were 40.4% and 13.3% respectively in the no PCI group vs 14.6% and 27.1% in PCI group. In the PCI group, brain metastases HR was 0.27 (95% CI, 0.16-0.44; p<0.001).
Comparatively, a Japanese phase III multicenter randomised trial compared PCI to no PCI in patients with extensive SCLC with any response to platinum-based doublet chemotherapy.r Of the 224 patients, 113 were randomised to PCI and 111 to observation. All patients were required to have 3 monthly brain MRI imaging for 12 months, then at 18 and 24 months after enrolment. Median overall survival was 11.6 months in the PCI group versus 13.7 months in the MRI surveillance group (HR 1.27, 95% CI 0.96-1.68; p=0.094). The most frequent grade 3 or worse adverse events were anorexia (6% versus 2%), malaise (3% versus < 1%) and lower limb muscle weakness (<1% versus 5%). In the PCI arm 54 (48%) patients and 77 (69%) patients in the observation arm developed brain metastases. Of those that developed brain metastases, 25 (46%) patients in the PCI arm and 64 (83%) patients in the observation arm went on to receive RT for brain metastases. This study lacked the inclusion of neurocognitive and functional assessments other than the mini-mental state examination (MMSE).
Hippocampal sparing
In a recent phase III trial, 150 patients with SCLC (71.3% with limited disease) were randomised to standard PCI (25 Gy in 10 fractions) or hippocampal avoidance (HA)-PCI.r Cognitive function was assessed with the Free and Cued Selective Reminding Test (FCSRT). Decline on delayed free recall from baseline to 3 months was lower in the HA-PCI arm (5.8%) compared with the PCI arm (23.5%). Decline on the total recall was reduced with HA at 3 months (8.7% v 20.6%), 6 months (20.3% v 38.9%) and 24 months (14.2% v 47.6%). The incidence of brain metastases, overall survival, and quality of life were not significantly different.
Another phase III trial included 168 patients with SCLC treated with standard PCI or HA-PCI at a dose of 25 Gy in 10 fractions.r Decline on the Hopkins Verbal Learning Test-Revised total recall score at 4 months was not significantly different between the arms. The cumulative incidence of brain metastases at 2 years did not differ according to treatment arms and was 20% for the PCI arm and 16% for the HA-PCI arm.