Dr. Weeks’ Comment: Ask your oncologist to quantitate your circulating tumor cells…
Improving Prognostic Accuracy with Circulating Tumor Cells
A crucial step in evaluating a cancer patient relies on establishing an accurate prognosis, which provides a prediction of the probable course and outcome of the disease. With a correct prognosis in hand, doctors can then design the most appropriate treatment for a person’s cancer.
Currently, the ability to provide an accurate prognosis is far from perfect. To investigate if circulating tumor cell (CTC) testing can improve prognostic accuracy, German scientists studied 35 women with non-metastatic breast cancer who had their levels of CTC measured before they had received any treatment for their cancer.2 Of these patients, 17 tested positive for CTC, while 18 tested negative for CTC. When the researchers looked at the prognoses of the two groups they found striking differences. The group that tested negative for CTC had a median overall survival of 125 months. The group with 5 or more CTC present in their blood had a median overall survival of only 61 months! The difference in survival of over 5 years between the two groups reveals the great importance that the presence and number of CTC had on the prognoses of this group of women with breast cancer. The findings of this study can have huge implications in how treatment is tailored for the individual with breast cancer. A key issue in breast cancer treatment is distinguishing at the outset which women have cancers that are low risk that do not require intensive treatment, and which women have a high risk of metastasis that requires aggressive treatment. This study provides a glimpse into the potential of CTC testing to provide a more accurate prognosis to allow doctors to distinguish high-risk from low-risk breast cancer patients.
In a related study, researchers at the University of Texas M. D. Anderson Cancer Center measured CTC in 151 women with metastatic breast cancer.3 These patients were also evaluated for other prognostic cancer markers, such as hormone receptor status, CA 27.29 (a blood marker that helps to measure the degree of breast cancer metastatic activity), and HER2 status. Those who had 5 or more circulating tumor cells (CTC) had a median overall survival of 13½ months. The median overall survival for those with less than 5 CTC was over 29 months. The researchers also discovered that the presence of 5 or more CTC had the highest predictive value compared to all other tumor markers! The researchers went on to boldly state that “circulating tumor cells have superior and independent prognostic value…”
Furthermore, recent research indicates that CTC evaluation can be used to predict prognosis for men with prostate cancer. Researchers at Thomas Jefferson University compared the levels of CTC in 37 men with metastatic prostate cancer. Their findings were remarkable””for the men with 5 or more CTC, the median overall survival was only 8.4 months. For those men with less than 5 CTC the median overall survival was 48 months!4 Yet another study measured CTC in 55 men with a rising PSA after surgery for prostate cancer.5 A rising PSA after surgery is strongly predictive of prostate cancer recurrence.6 Radiation therapy was administered to 15 patients. Of these prostate cancer patients, 60% who were CTC positive had progression of their disease during radiation therapy, while there were no disease progressions in the CTC negative group!5 Additional studies have confirmed these results.7-8