The normal blood platelet count for a patient undergoing cancer treatment ranges from 150,000 to 450,000, according to Mayo Clinic. Doctors consider a blood platelet count of under 20,000 concerning, Blood platelets assist blood clotting, and a low blood platelet count makes it difficult for the body to stop bleeding.
Chemotherapy, radiation therapy, blood and bone marrow cancers, and cancers that metastasize are all causes of low blood cell counts, according to Mayo Clinic. Low blood cell counts can cause severe complications with cancer treatments, such as anemia, infection and bleeding. A low platelet count can delay cancer treatment until the level rises to a safe range.