The United States is currently experiencing a significant number of drug shortages, with cancer treatments being among the most affected.

According to data from the University of Utah Drug Information Service as of the end of March, there is an active shortage of about two dozen chemotherapy drugs, making it the fifth most affected drug category. The shortage of cancer drugs has resulted in delays and cancellations of cancer treatments, putting patients at risk.

“The fact that we have this many chemo drugs in shortage is really concerning,” said Michael Ganio, senior director of pharmacy practice and quality at the American Society of Health-System Pharmacists.

Unlike some other drugs that also rank among the top five categories for shortages, such as antimicrobials, there aren’t often alternatives for chemotherapy drugs, he said. And the shortages are affecting treatment for a broad range of cancers.

“One of the key predictors of how well a patient will respond to treatment is getting a full dose on the right schedule,” Ganio said. “So when we can’t give the drug because we just can’t get the drug, that’s heartbreaking.”

Overall, data from the University of Utah shows that there were more than 300 drugs with an active shortage in the U.S. at the end of March, including nearly 50 new shortages that accumulated in the first three months of the year.

The last time active drug shortages – including both newly reported and ongoing – were this high was in 2014, the data shows.

“Shortages are still happening, and they’re not resolving, or they’re not resolving as quickly as new shortages are starting,” Ganio said.

On Thursday, the U.S. House of Representatives Energy and Commerce Subcommittee on Oversight and Investigations held a hearing exploring the root causes of these shortages.

Increased demand is part of it. But experts say that some high-profile shortages – such as amoxicillin during the most recent respiratory virus season and Adderall for ADHD – are the exception.

“They don’t really tell the story of drug shortages,” Ganio said.

Instead, the hearing was more heavily focused on manufacturing issues and the broader structure of the drug market in the U.S.

The U.S. Food and Drug Administration, in particular, was criticized for falling behind on inspections, especially of international facilities that represent more than half of manufacturers that supply the U.S.

A report from the Government Accountability Office, a federal watchdog agency, in January 2022 noted “longstanding challenges” facing the FDA’s Foreign Inspection Program and called for more formal steps to improve it.

Effective inspections of both domestic and foreign manufacturing facilities are “absolutely essential for ensuring the quality and the safety of the medicines that U.S. citizens consume,” said Anthony Sardella, chair of the API Innovation Center, a nonprofit focused on building the supply of U.S.-made pharmaceuticals.

“They’re also extremely important in ensuring the stability of the market,” said Sardella, who was a witness at the hearing.

But in a hearing Thursday of the Energy and Commerce Subcommittee on Health, FDA Commissioner Dr. Robert Califf said that the economic issues underlying drug shortages are “not in the purview of the FDA.”

The FDA is “plugging holes in the dike,” he said, but it’s difficult to motivate change when it’s not profitable for drug companies.

“These drug shortages are becoming more prevalent due to a warped marketplace,” said Rep. Kathy Castor, D-Florida, ranking member on the subcommittee.

“The current haphazard approach of addressing crisis episode-by-episode is not working to give American families the certainty and the quality of care they need and deserve.”

Hundreds of impending shortages loom, and Califf called on drug companies to alert the FDA to them.

“Each company doesn’t know what the other company’s doing because they’re competing,” he said. “When there’s a shortage in one company, we need to be able to coordinate across these people.”

Abby is doing well now, but 9 out of 10 oncologists say that drug shortages have led to patient harm, including death, said Bray, who was a witness at the Oversight hearing Thursday.

“Patients deserve access to these medicines. The physicians and nurses and care team who are trying to solve these crises and save them deserve easy and equal access to these medicines.”

CNN’s Jacqueline Howard and Betsy Klein contributed to this report.