The media has a penchant for hailing new medical "breakthroughs" and "miracles" — even when there's no evidence to back up those claims.

Now researchers have quantified how often this baseless overhype actually occurs. Spoiler: It's very common, so be wary whenever you see those terms.

A group of American cancer researchers, writing in this week's issue of the journal JAMA Oncology, measured how often 10 superlatives were used to describe new cancer drugs in the press. (The list of terms included "breakthrough," "game changer," "miracle," "cure," "home run," "revolutionary," "transformative," "life saver," "groundbreaking," and "marvel.") They searched Google News to see when these phrases were used in connection with cancer drugs, and then read the articles to see if there was any evidence to back up the wild claims.

In half the cases, terms like "breakthrough," "miracle," and "cure" were used to describe medicines that hadn't even been approved yet by regulators. So not only were these drugs not yet available to patients, they also hadn't even passed scrutiny by the Food and Drug Administration. Even worse, about 14 percent of the time these terms were used, the drugs actually had no human data behind them. This means journalists were calling a drug a "miracle" or "cure" when it had only been tested on mice or cell cultures.

The most frequent medications being hyped were targeted drugs such as immunotherapies, which are right now considered the vanguard of cancer research.

So who's to blame for overhype? The superlatives were most commonly deployed by journalists themselves — in about 55 percent of cases. But it's not just the media at fault here. In about 30 percent of cases, doctors themselves were quoted using language like "miracle" or "game changer" to describe new cancer drugs, often without good justification. This jibes with other studies finding that a great deal of medical hype in the press often comes from universities and hospitals themselves.

Medical overhype has become a pervasive problem. Overselling not only misleads patients but also helps inform misguided policies, pressures regulators to speed through substandard drugs, and, worst of all, creates false hope in people who may be desperate for cures that never come. It has to stop.