Keio University said two of its School of Medicine doctors extracted bone marrow from patients without their consent in violation of government ethical guidelines.

They include a professor in his 50s who has engaged in clinical research on cancer cells and extracted rib bone marrow from multiple lung cancer and other patients during surgery without providing explanations to them or gaining their consent, the university said Monday. The university has suspended their authority at its hospital and is considering disciplinary action against them.

In its ethics guidelines, the health ministry calls on doctors to provide sufficient explanations to patients and obtain their consent for bone marrow extraction.