Purpose The breakthrough therapy program was established in 2012 to expedite the development and review of new medicines. We evaluated the times to approval, efficacy, and safety of breakthrough-designated versus non-breakthrough-designated cancer drugs approved by the US Food and Drug Administration (FDA). Methods We studied all new cancer drugs approved by the FDA between January 2012 and December 2017. Regulatory and therapeutic characteristics (time to FDA approval, pivotal trial efficacy end point, novelty of mechanism of action) were compared between breakthrough-designated and non-breakthrough-designated cancer drugs. Random-effects meta-regression was used to assess the association between breakthrough therapy designation and hazard ratios for progression-free survival (PFS), response rates (RRs) for solid tumors, serious adverse events, and deaths not attributed to disease progression. Results Between 2012 and 2017, the FDA approved 58 new cancer drugs, 25 (43%) of which received breakthrough therapy designation. The median time to first FDA approval was 5.2 years for breakthrough-designated drugs versus 7.1 years for non-breakthrough-designated drugs (difference, 1.9 years; P = .01). There were no statistically significant differences between breakthrough-designated and non-breakthrough-designated drugs in median PFS gains (8.6 v 4.0 months; P = .11), hazard ratios for PFS (0.43 v 0.51; P = .28), or RRs for solid tumors (37% v 39%; P = .74). Breakthrough therapy-designated drugs were not more likely to act via a novel mechanism of action (36% v 39%; P = 1.00). Rates of deaths (6% v 4%; P = .99) and serious adverse events (38% v 36%; P = 0.93) were also similar in breakthrough-designated and non-breakthrough-designated drugs. Conclusion Breakthrough-designated cancer drugs were associated with faster times to approval, but there was no evidence that these drugs provide improvements in safety or novelty; nor was there a statistically significant efficacy advantage when compared with non-breakthrough-designated drugs.