When somebody has an active cancer, the cancer cells die almost as fast as they grow. But unfortunately, they grow somewhat faster, which is what gets people in trouble. But the dying cancer cells release these abnormal proteins into the blood stream, these tumor markers, and enables us to roughly approximate the growth of the tumor that the person is suffering from. So, it's not an exact science, but it's pretty accurate, and we correlate that to structural measurements that we get through scans, CAT scans, MRIs, ultrasounds, and the like, and between the two, we're able to correlate the patient's progress and see how things are going.
Once the tumor is put into remission, whether it be through the activities of chemotherapy, radiation, surgery, low-dose fractionated chemotherapy or immunotherapy, then the cancer over a period of time often has a tendency to try to recur because the thing that allowed the cancer to begin with at the very start of things has not been addressed, and that issue was an area of damage to our immune system to begin with. Unfortunately, the treatment step we use nowadays for patients with cancer, chemotherapy and radiation all increase the level of damage and dysfunction to our immune system, which is kind of a Catch-22 if you will, but nonetheless, there we go.