Sickle cell disease and cancer risk present conflicting clinical evidence

When two patients developed blood cancers during clinical trials for a new sickle cell gene therapy three years ago, federal regulators hit the brakes.

The treatment itself, Lyfgenia, was eventually cleared. Federal investigators concluded the modified viruses used in the lab did not cause the leukemia. But the temporary halt pushed a long-simmering medical dilemma back into the open: do people living with sickle cell disease face a higher risk of cancer simply because of the illness they carry?

Decades of hospital records have failed to settle the question. If anything, the numbers are a contradictory mess.