Stephanie Scanlan learned about the shortages of basic chemotherapy drugs this spring in the most frightening way. Two of the three drugs typically used to treat her rare bone cancer were too scarce. She would have to go forward without them.
Ms. Scanlan, 56, the manager of a busy state office in Tallahassee, Fla., had sought the drugs for months as the cancer spread from her wrist to her rib to her spine. By summer it was clear that her left wrist and hand would need to be amputated.
“I’m scared to death,” she said as she faced the surgery. “This is America. Why are we having to choose who we save?”
The disruption this year in supplies of key chemotherapy drugs has realized the worst fears of patients — and of the broader health system — because some people with aggressive cancers have been unable to get the treatment they need.
Those medications and hundreds of other generic drugs, including amoxicillin to treat infections and fentanyl to quell pain during surgery, remain in short supply. But the deepening crisis has not fostered solutions to improve the delivery of generic drugs, which make up 90 percent of prescriptions in the United States.
Dr. Robert Califf, commissioner of the Food and Drug Administration, has outlined changes the agency could make to improve the situation. But he said the root of the problem “is due to economic factors that we don’t control.”
“They’re beyond the remit of the F.D.A.,” he said.
Senator Ron Wyden, a Democrat of Oregon and chairman of the Senate Finance Committee, agreed. “A substantial portion of these market failures are driven by the consolidation of generic drug purchasing among a small group of very powerful health care middlemen,” he said at a hearing this month.
In interviews, more than a dozen current and former executives affiliated with the generic drug industry described many risks that discourage a company from increasing production that might ease the shortages.
They said prices were pushed so low that making lifesaving medicines could result in bankruptcy. It’s a system in which more than 200 generic drugmakers compete, at times fiercely, for contracts with three middleman companies that guard the door to a vast number of customers.
In some cases, generic drugmakers offer rock-bottom prices to edge out rivals for coveted deals. In other instances, the intermediaries — called group-purchasing organizations — demand lower prices days after signing a contract with a drugmaker.
The downward pressure on prices — no doubt often a boon to the pocketbooks of patients and taxpayers — is intense. The group purchasers compete against one another to offer hospitals the lowest-priced products, which intermediary companies say also benefits consumers. They earn fees from drugmakers based on the amount of medications the hospitals buy.
“The business model is broken,” said George Zorich, a pharmacist and retired generic drug industry executive. “It’s great for G.P.O.s. Not great for a …