Two months after Gilead Sciences Inc.'s breakthrough treatment was approved in the U.S. to treat a deadly form of blood cancer, only a tiny handful of patients have actually gotten the costly therapy, while others linger on waiting lists.

Five people have received the treatment, called Yescarta, at the 15 cancer hospitals authorized to administer it in the U.S., the hospitals told Bloomberg. Waiting lists for the $373,000 treatment have grown to at least 200 people, shrinking only as some very sick patients have died.

Doctors at the cancer centers blame holdups in getting the treatment paid for by Medicare and Medicaid, the two giant U.S. government health programs, as well as some of the U.S.'s largest insurers.