Ten RCTs (2,609 participants) were included. None of the trials were placebo-controlled double-blind trials.
No significant difference was found between adjuvant therapy compared to no treatment on overall survival (HR 1.07, 95% CI 0.89 to 1.28, I2=0%; six RCTs) and disease-free survival (HR 1.03, 95% CI 0.87 to 1.21, I2=26%; nine RCTs) outcomes. Subgroup analysis of different adjuvant therapies (immunotherapy, vaccines, biochemotherapy and hormone therapy) revealed no significant effects on survival outcomes.
Vaccine and immunotherapy were reported to cause mild but frequent skin induration, injection site pain and flu-like symptoms. In one trial, vaccine therapy when compared to no treatment was associated with a significantly higher risk of grade 3/4 neutropenia (RR 62.33, p=0.004) but no effect was found on anaemia.
No evidence of publication bias was found.