Testing Cancer Cell Division with Thymidine Kinase-1 Testing
One of the challenges of cancer diagnosis and monitoring is that patients often must be exposed to high levels of ionizing radiation. This happens with CT scans, X-rays, PET scans and other types of imaging. While the information is often very valuable, it comes with a price. A CT scan with and without contrast of the abdomen and pelvis, for example, is a radiation exposure that is about 200 times that of a chest X-ray.
The use of blood-based markers is ideal, but these markers are of limited value. Some are commonly used - CA15-5 for breast cancer, CEA for colorectal cancer, CA19-9 for pancreatic cancer, etc. - but always with qualifications about their potential problems. It is in this context that a reliable blood-based marker for cancer is very exciting.
cing thymidine kinase-1, or TK-1, a very important enzyme in all of our dividing cells. Each time a cell divides, TK-1 comes in to make sure that any errors in the DNA being copied are repaired. This prevents the damage from being passed along to the new cell. Healthy cells have very few DNA errors to repair, so little TK-1 is needed. Cancer cells, though, contain lots of DNA errors. Thus, they use lots of TK-1.
An increasing number of studies are showing elevated levels of TK-1 to be a very sensitive indicator of cancer cell division. The more TK-1 found in the blood, the more likely that cancer cell division is occurring. Most importantly, in patients previously treated for cancer and declared "no evidence of disease," TK-1 elevations correlate with a risk of recurrent cancer. Most studies on this are technical reading, but here is the punch line of a recent review of TK-1 testing for breast cancer:
"In conclusion, for patients with recurrent breast cancer, high tumor TK activity is a significant marker of poor clinical outcome on tamoxifen therapy." (here's the article)
Dr. Nigh is using a set of tests to monitor the efficacy of the cancer treatment programs we're using. Most of these are metabolic tests. This means that they measure the activity of cancer cells rather than the more traditional tests that look for markers on the surface of those cells. TK-1 testing is a welcome addition to the set of tests that Immersion Health can offer to patients. It has been invaluable to patients in the "wait and see" period following successful prior treatment of their cancer. TK-1 testing can indicate a need to be more aggressive with preventative therapies during this period.
If you have a current or past diagnosis of cancer, and would like to learn more about what TK-1 testing can tell you, call the clinic at 503-719-4806 or email firstname.lastname@example.org. During a free 15-minute consultation Dr. Nigh can explain more about this and other testing we do for our cancer patients.