My pcp informed me that my white blood cell count, which was repoted low on a blood test a year ago, has further declined. He suggested that I see a hematologist, whom he said is also an oncologist. Can you help me to understand what type(s) of cancer might cause a low white blood cell count? I already know the basics about white blood cells, their purpose, and that they are manufactured in my bone marrow. Thank you for all the knowledge you can share with me about this.