MEMPHIS  — A national drug shortage has been linked to a higher rate of relapse among children, teenagers and young adults with Hodgkin lymphoma enrolled in a national clinical trial, according to research led by St. Jude Children's Hospital.

The study found the estimated two-year cancer-free survival for patients enrolled in the study fell from 88% to 75% after the drug cyclophosphamide was substituted for mechlorethamine for treatment of patients with intermeidiate- or high-risk Hodgkin lymphoma. The study was launched before the drug shortages began.

The change occurred after a mechlorethamine shortage that began in 2009. No study patients have died, but relapsed patients needed additional intensive therapy associated with higher odds for infertility and other health problems.

The full analysis appears in the Dec. 27 edition of the New England Journal of Medicine.