Ladies and gentlemen, first I would like to thank ASCO for allowing me to present these results on behalf of Professor Bjørn Edwin and Dr Kazaryan and a large group of researchers at Oslo University Hospital.

Colorectal cancer is one of the top four cancers in the United States with more than 160,000 new cases each year. Half of these patients get liver metastases but thanks to advances in oncologic treatment and in surgical knowledge more and more of these patients can be operated. Open surgery has been the standard operation for liver metastases but laparoscopic, or keyhole, surgery is considered a minimally invasive alternative to open surgery. However, a recent survey showed that only 22% of United States patients with colorectal liver metastases that have a surgery for it have laparoscopic surgery. Our trial is the first to compare laparoscopic and open liver surgery for colorectal metastases.

We designed a randomised controlled trial to find out if laparoscopic liver surgery is better for the patients than open liver surgery. The primary outcome was postoperative complications within thirty days. We included patients from 2012 to 2016, a total of 280 patients. All the patients had what we call parenchymal sparing surgery or liver sparing surgery, a surgical technique that removes only the tumour and leaves behind a maximum amount of healthy liver tissue. Our group had a large experience of laparoscopic liver operations before the study started, as much as 400 operations. We pre-planned a survival analysis three years after the last operation and these are the data we are here to present.

First, the short-term outcomes. Laparoscopic liver surgery was in general better tolerated by the patients, they had less complications - 19% versus 31% in the open group. The hospital stay was shorter, only two days versus four days in the open group, and they reported better quality of life up to four months after surgery. In a cost-effectiveness analysis we couldn’t find a difference in costs and with better quality of life and similar costs we could state that laparoscopic liver surgery was cost-effective. These data have been published in Annals of Surgery last year.

These are the long-term outcomes after a median observation time of 45 months. Overall survival was the same for laparoscopic and open liver surgery, a five year overall survival of 57% in the open group and 56% in the laparoscopic group, no difference. The chances of disease recurrence were also the same with a five year recurrence free survival of 31% in the open group and 29% in the laparoscopic.

These are the Kaplan-Meier curves. We see that more than half of the patients that have surgery for colorectal liver metastases, colon cancer that has spread to the liver, live for more than five years after the liver surgery. Furthermore, we see that patients get recurrences but the recurrences can also be removed. A total of 55 patients have so far undergone repeated liver resections for recurrent metastases and also 16 patients have been operated for a lung metastasis following the liver surgery.

To conclude, ladies and gentlemen, laparoscopic liver surgery did not change the chances for survival compared to open liver surgery. Laparoscopic surgery was better for the patients at no additional cost to society. We hope that these results will encourage more hospitals to establish a laparoscopic liver surgery programme. This has to include structured training of the surgeons. Thank you so much.