During the same months, Rainer diagnosed himself with lung cancer, which was another probable effect of his long exposure to formaldehyde fumes. He tried to hide this from his wife and his friends, claiming his problem was a mere case of paresis. His house was narrowly missed by the April 1944 bombardment, and he had to move into the house of a former assistant, Ion Țurai. He was later moved to Hospital No. 303, where he developed metastasis in the brain.