Do circulating tumor cell markers of have both prognostic and predictive values?

This study evaluated markers of circulating tumor cells as prognostic factors and predictive factors in patients with metastatic colorectal cancer.

Metastatic colorectal cancer (mCRC) is cancer whereby tumor cells have spread from the colon or rectum to other organs and tissues. The cells that escape from the primary tumor and settle down at a secondary site to cause metastasis are called circulating tumor cells (CTCs). 

Many studies have demonstrated the prognostic (showing cancer outcome) value of circulating tumor cells in several cancer types. However, their predictive (indication of therapy response) value remains unclear. This study evaluated the ability of DNA markers of circulating tumor cells to show disease outcome and predict therapy effectiveness in patients with metastatic colorectal cancer.

This study analyzed six different DNA markers of circulating tumor cells (GAPDH, VIL1, CLU, TIMP1, LOXL3 and ZEB2) from a total of 50 metastatic colorectal cancer patients receiving various treatments. Patients were divided into two groups; those with low and those with high levels of the markers analyzed.

At the beginning of the study, patients with low levels of markers showed a significantly longer progression free survival (defined as the time the patient survives without worsening of the cancer) and longer overall survival compared to those with high levels of markers. Patients with high levels of markers had a progression-free survival of 6.3 months versus 12.7 months in patients with low levels of marker.  Patients with high levels of markers had an overall survival of 12.7 months versus 24.2 months for patients with low levels of markers.

After four weeks of treatment follow-up, 30% of the patients had increased levels of circulating tumor cell markers while 70% showed a reduction in circulating tumor cell markers. Patients with increased levels of markers had a progression-free survival of 6.6 months versus 12.7 months in those with a reduction in levels of markers. Patients with increased levels of markers had an overall survival of 13.1 months versus 24.3 months in those with a reduction in marker levels. This showed that the level of circulating tumor cell markers correlated with patient response to therapy.  

In addition, a further analysis showed that markers of circulating tumor cells increased detection sensitivity compared to standard detection techniques.

In summary, this study concluded that the multimarker panel of six selected circulating tumor cell markers may be used for prognosis and prediction in patients with metastatic colorectal cancer.

This study involved only a small number of patients, and was followed for a short period.