IPD from 6 RCTs (n=493) were included.
Survival analyses were based on 283 events and 491 patients across all 6 trials. Overall, a 25% relative reduction in risk of death was shown for chemotherapy compared with the control group: the HR was 0.75 (95% CI: 0.60, 0.96), equivalent to an absolute improvement in survival of 9% (95% CI: 1, 16). No statistical heterogeneity was found. When compared with no adjuvant therapy, cisplatin as a single agent did not improve overall survival (HR 1.02, 95% CI: 0.57, 1.84). However, cisplatin-based combination chemotherapy showed a 29% relative decrease in risk of death compared with local treatment alone (HR 0.71, 95% CI: 0.55, 0.92).
Disease-free survival analyses were based on 239 events and 383 patients across 5 trials. A 32% relative decrease in the risk of recurrence or death was shown for chemotherapy compared with the control (HR 0.68, 95% CI: 0.53, 0.89), equivalent to an absolute improvement in disease-free survival of 12% (95% CI: 4, 19) at 3 years. No statistical heterogeneity was found. Cisplatin-based combination chemotherapy showed a 38% relative decrease in risk of recurrence or death compared with controls (HR 0.62, 95% CI: 0.46, 0.83).
Locoregional disease-free survival and metastases-free survival analyses were not presented since only limited data were available.
There was no evidence of any difference in the effectiveness of chemotherapy across subgroups based on patient characteristics.