P-300 - Circulating tumour cell release in the peri-operative setting during curative colorectal cancer surgery

Date 04 July 2015
Event WorldGI 2015
Session Posters
Topics Colon Cancer
Rectal Cancer
Translational Research
Surgery and/or Radiotherapy of Cancer
Presenter K. Spring
Citation Annals of Oncology (2015) 26 (suppl_4): 1-100. 10.1093/annonc/mdv233
Authors K. Spring1, S. Lim2, J. Descallar3, W. Ng4, W. Chua4, P. de Souza4, L. Bokey4, S. MacKenzie4
  • 1Ingham Institute/University of Western Sydney, Sydney/AU
  • 2Ingham Institute/Liverpool Hospital, Sydney/AU
  • 3Ingham Institute, Sydney/AU
  • 4Liverpool Hospital, Sydney/AU

Abstract

Introduction

Circulating tumour cells (CTCs) have prognostic and predictive utility in colorectal cancer. Their role in the perioperative setting is unclear, with some evidence that CTCs are disseminated at time of surgery and may contribute to metastatic disease.

Aims

We measured CTCs prospectively in 40 samples, taken at 4 time-points from 10 patients undergoing curative colorectal surgery, namely at baseline (T1), post mobilisation of tumour (T2), immediately post surgery (T3) and day 1 post surgery (T4). We correlated CTCs with tumour stage and right-or left sidedness. We also measured CTCs in 10 healthy controls.

Methods

CTC isolation was performed on a 9ml peripheral blood sample by immunomagnetic separation using the IsoFluxTM platform. CTCs were defined as, cytokeratin and DAPI positive, and CD45 negative by immunofluorescence. Negative binomial models were used for analyses (unless otherwise stated), and significance set at p = 0.05.

Results

The median patient age was 66 years, with 60% male. 4 cases were right-sided cancers which underwent a right hemicolectomy and 6 cases were left-sided cases which underwent an anterior resection or abdominoperineal resection. 50% of cases were node-positive, and the average number of nodes dissected was 18.

Mean CTC count at baseline (T1) in all patients was 7 (range 0-29) and counts at T2, T3 and T4 were 12 (range 0-55), 5 (range 0-38) and 9 (range 0-57) respectively. Mean control CTC count was 2. Baseline CTC counts were significantly different to controls, with cases having 3.6 times more CTCs than controls (p = 0.0082). There was a trend towards CTCs at post-mobilisation of tumour being 1.8 times higher than baseline counts (p = 0.0667). CTCs immediately post surgery were 1.8 times significantly lower than day 1 post surgery (p = 0.001). There was no correlation between baseline CTCs and T or N stage. There was no confounding between right/left sidedness with T or N stage (Fisher's exact test). CTCs were significantly higher in right-sided cases, being 8.9 times that of left-sided cases (p < 0.001). In the right-sided surgeries, there was a significant rise, by 2-fold, in CTCs post tumour mobilisation compared to baseline (p = 0.0423)

Conclusion

We have shown that CTCs are present in patients undergoing curative colorectal surgery. There is a suggestion of a surge in CTCs post tumour mobilisation, which is significant in right-sided cancers undergoing right hemicolectomy. CTC counts at baseline are higher in right-sided cancers. There is a significant nadir in CTC counts immediately post surgery. This dataset is being expanded to confirm these findings.