The studies show patients with breast cancer or advanced cervical cancers who took anemia drugs known as erythropoiesis-stimulating agents, or ESAs, died sooner or had more rapid tumor growth than similar patients who didn't receive the anemia drug.

The two new studies, along with the six studies previously reviewed by the FDA, show more rapid tumor growth or shortened survival when patients with breast, non-small cell lung, head and neck, lymphoid or cervical cancers received ESAs.

"This new information further underscores the safety concerns regarding the use of ESAs in patients with cancer, which FDA addressed in previous communications," Dr. Janet Woodcock, acting director of the Center for Drug Evaluation and Research, said Thursday in release.