After extensive testing it was found that Onatello's Bronchial tumors are not cancer, but that he is battling a case of Viral Pneumonia and is on the road to recovery.
Pneumonia is a sickness where fluid builds up in your lungs. Some people get it if they have a bad cold/case of the flu and dont have the strongest immune systems. In this case it was caused by a virus, which means its a bit harder to treat but im sure hes better now..