Betsy Lucas was five months pregnant when a curious dime-sized lump arose on her neck.

Her family doctor thought it was likely an inflamed lymph node caused by a recent sinus infection. But a biopsy revealed Betsy had Burkitt lymphoma, a fast-growing type of non-Hodgkin lymphoma that occurs most often in young adults and children.

“I was stunned,” Betsy says. “The bump appeared out of nowhere, overnight.”

Pregnancy...