Is newer always better? When it comes to cancer drugs, maybe not, a new study has found.

While recent years have seen a rush to market for dozens of pricey new cancer meds, JAMA Oncology researchers reported that actual patient outcomes vary widely throughout a group of 53 drugs approved by health authorities in the U.K., France and Australia through May 2015.

Even though cancer treatment overall has seen improvements with groundbreaking new therapies, “the magnitude and dimension of clinical benefits” aren’t uniform, the authors wrote, adding that “there may be reasons to doubt that claims of efficacy reflect real-world effectiveness exactly.”

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Of the group of 53 meds, researchers Sebastian Salas-Vega, Othon Iliopoulos and Elias Mossialos found that 43% increased overall survival by three months or longer. Vastly fewer patients, 11%, improved that metric by less than 3 months, while 15% increased survival by an unknown amount.

The remaining 30% of drugs in the group? The researchers couldn’t find evidence to demonstrate they helped with overall survival over existing treatments at all.

Twenty two drugs came with a quality of life improvement, but 24 were associated with reduced safety. All told, 42 drugs—79% of the group—came with “at least some” improvement in survival, quality of life or safety over older therapies, meaning 11 didn't post a documented benefit.

“As calls for value-based healthcare grow, this analysis raises questions about how clinical benefits are measured by regulators, how regulatory guidance is used to inform clinical decisionmaking, and how much value is generated from spending in the oncology drug market,” the authors concluded.

Indeed, payers and health systems in recent years have increasingly tracked real-world effectiveness as rising drug costs have pressured them to make tough decisions. Express Scripts, for one, introduced indication-specific pricing in late 2015 to favor “clinically superior” drugs.

That’s in addition to a push by several drugmakers to move into value-based pricing, with many payers coming onboard to strike coverage deals.

After following the industry for more than 20 years for consultancy firm Trinity Partners, founder John Corcoran recently said he expects concepts such as “real-world evidence,” “outcomes,” “cost effectiveness,” and “health economics” to play a bigger role than ever moving forward.