Asked for female, 19years old from Nellore
Thick blood is usually not a sign of blood cancer. Blood thickness if due to polycythemia vera ie raised hemoglobin is classified as myeloproliferative neoplasm. But the chances of it progressing to blood cancer is extremely rare especially if it is treated properly.
Thick blood could be because of abnormalities in proteins of the coagulation system.
Durability depends on the underlying cause.