Seeding of epithelial cells into circulation during surgery for breast cancer: the fate of malignant and benign mobilized cells

Abstract

Background: Surgery of malignant tumors has long been suspected to be the reason for enhancement of growth of metastases with fatal outcome. This often prevented surgeons from touching the tumor if not absolutely necessary. We have shown in lung cancer patients that surgery, itself, leads to mobilization of tumor cells into peripheral blood. Some of the mobilized cells finding an appropriate niche might grow to form early metastases. Monitoring of tumor cell release during and the fate of such cells after surgery for breast cancer may help to reveal how metastases develop after surgery.

Method: We used the MAINTRAC analysis, a new tool for online observation of circulating epithelial cells, to monitor the number of epithelial cells before, 30 min, 60 min, three and seven days after surgery and during subsequent variable follow up in breast cancer patients.

Results: Circulating epithelial cells were already present before surgery in all patients. During the first 30-60 min after surgery values did not change immediately. They started increasing during the following 3 to 4 days up to thousand fold in 85% of treated patients in spite of complete resection of the tumor with tumor free margins in all patients. There was a subsequent re-decrease, with cell numbers remaining above pre-surgery values in 58% of cases until onset of chemotherapy. In a few cases, where no further therapy or only hormone treatment was given due to low risk stage, cell numbers were monitored for up to three years. They remained elevated with no or a slow decrease over time. This was in contrast to the observation in a patient where surgery was performed for benign condition. She was monitored before surgery with no cells detectable. Epithelial cells increased up to more than 50,000 after surgery but followed by a complete reduction to below the threshold of detection.

Conclusion: Frequently before but regularly during surgery of breast cancer, epithelial cells are mobilized into circulation. Part of these cells, most probably normal or apoptotic cells, are cleared from the circulation as also shown to occur in benign conditions. After resection even if complete and of small tumors, cells can remain in the circulation over long times. Such cells may remain "dormant" but might settle and grow into metastases, if they find appropriate conditions, even after years.

Figure 1

Positively stained gated green fluorescing cells which have been relocalized and visually analyzed. Typical pictures of such cells detected by their green fluorescing cap are shown.

Figure 2

Analysis of the number of circulating cells from 11 patients immediately before and 30 and 60 min after surgery.

Figure 3

Increase and decrease of circulating cells of 25 patients before and 3 and 6 days after surgery for breast cancer setting pre-surgery values 100%. The fat dotted line with squares represents the mean increase and decrease of all 25 patients. Two patients (one during cryotherapy and one with DCIS (fat lines) retain identical numbers during intervention.

Figure 4

% of pre-surgery values of recirulating cells until onset of adjuvant chemotherapy.

Figure 5

Numbers of longtime recirculating cells in patients without adjuvant chemotherapy. Two patients (orange and blue (DCIS) line) have now been monitored more than three years always revealing almost identical number of recirculating cells. In contrast, in a patient without a solid tumor (dotted line) who underwent surgery for a benign condition, cells returned to below the threshold of detection without further treatment.