Objectives: This is a systematic review of evidence on issues in managing small cell lung cancer (SCLC). Key questions addressed are: the sequence, timing, and dosing characteristics of primary thoracic radiotherapy (TRTx) for limited-stage disease; primary TRTx for extensive-stage disease; effect of prophylactic cranial irradiation (PCI); positron emission tomography (PET) for staging; treatment of mixed histology tumors; surgery; and second- and subsequent-line treatment for relapsed/progressive disease.
Data sources: MEDLINE, EMBASE, and the Cochrane Register
Review methods: The review methods were defined prospectively in a written protocol. We sought randomized controlled trials that compared the interventions of interest. Where randomized trials were limited or nonexistent, we sought additional studies. We performed meta-analysis of studies that compared early and late TRTx.
Results: The strongest evidence available for this report is a patient-level meta-analysis showing that PCI improves survival of SCLC patients who achieved complete response following primary therapy from 15.3 percent to 20.7 percent (p=0.01). No other question yielded evidence so robust. The case for concurrent over sequential radiation delivery rests largely on a single multicenter trial. Support for early concurrent therapy comes from one multicenter trial, but two other multicenter trials found no advantage. Our meta-analysis did not find significant reductions in 2- and 3-year mortality for early TRTx. Favorable results from a single-center trial on TRTx for extensive stage disease need replication in a multicenter setting. For other questions (i.e., management of mixed histology disease; surgery for early limited SCLC), relevant comparative studies were nonexistent. PET may be more sensitive in detecting disease outside the brain than conventional staging modalities, but studies were of poor quality and reliable estimates of performance are not possible.
Conclusions: PCI improves survival among those with a complete response to primary therapy. A research agenda is needed to optimize the effectiveness of TRTx and its components. PET for staging may be useful, but its role awaits clarification by rigorous studies. No relevant evidence was available to address management of mixed histology disease or surgery for early limited SCLC.