Can circulating tumor cells help in improving the outcomes of patients with breast cancer?

This study evaluated the role of circulating tumor cells (CTCs) in deciding adjuvant therapy (AT; treatment after surgery) in patients with breast cancer (BC). This study showed that personalized AT based on CTCs improved patient survival.

BC that has not spread to other areas of the body is called non-metastatic (nm) BC. Tumor cells can be found within the bloodstream of patients with nmBC. These are called CTCs. CTCs can lead to the development of tumors in other parts of the body, even if the original tumor is treated. For this reason, patients can receive therapy for the breast tumor along with AT to treat the CTCs.

Many cancer cells have proteins on their surface that help them grow and multiply. ATs are commonly targeted against different types of these proteins on cancer cells. However, whether CTCs can be used to determine which ATs can be used in patients with nmBC and whether CTC-personalized treatment can improve patient survival remains under investigation.

This study had 2 parts. The first part of this study included 102 patients with nmBC. After surgery to remove the breast tumor, CTCs were detected in 67.7% of patients. Different ATs were given to these patients. Anthracyclines (AC) followed by paclitaxel (P; Taxol) was the most effective AT given to target the CTCs. After AC-P therapy, CTCs reduced from 52.6% to 15.8%.

The second part of the study included 128 patients. All patients had surgery to remove the breast tumor. Half of the patients were then given standard AT (group 1). The other half were given AT based on CTCs (group 2). Group 2 first received 2 courses of standard treatment which was changed based on CTCs response to ACs, then to paclitaxel, then to gemcitabine (Gemzar).

Group 1 had a 5-year survival rate of 78.7%. This was compared to 90.3% in group 2. 88% of patients in group 2 were disease-free after 5 years. This was compared to 80.6% in group 1.

12 patients in group 2 had all the treatment changes based on CTCs response. After the 4 courses of gemcitabine treatment, all 12 patients were free of CTCs.

This study showed that treating nmBC with personalized AT based on CTCs improves patients’ outcomes.

The study had a small sample size. Also, certain treatment options were evaluated in this study. Further investigation on AT based on CTCs are needed.