A fluorescence guided steerable laser tool for precision resection of early stage cancers

点击翻译按钮获取中文摘要

In the UK 40,000 people are diagnosed every year with colorectal cancer which carries a life-time risk of 1:16 for men and 1:18 for women. The National Bowel Cancer Screening Programme is proving effective, with a 16% survival benefit for screened individuals. Importantly, there has been a shift in the detection to earlier disease with screening colonoscopy picking up polyps in 40% of cases and cancers in 10% of cases. There is therefore a growing demand to remove these early precancerous/cancerous tumours by endoscopic means. However, the shift away from conventional surgery to endoscopic techniques presents challenges. Existing procedures using relatively cumbersome electrical cutting devices to apply heat to the tissue are challenging to perform due to restricted access and a lack of fine control for the surgeon. In some cases it is not possible to remove colonic lesions due to them occupying sites inaccessible to "forward facing" endoscopic excision methods. This results in a non-ideal procedure sometimes resulting in serious complications such as bowel perforation. Infrared lasers are attractive for surgery because the water in human tissue strongly absorbs this radiation. Additionally, "ultrafast" i.e. picosecond pulsed lasers deliver energy in such short pulses that thermal effects are minimal and tissue can be ablated with the resulting crater restricted only to the area on which the pulse was incident. Therefore, by precisely and flexibly delivering the energy to specific tumorous areas they can be cleanly removed minimising both damage to surrounding tissue and the risk of bowel perforation. Another advantage may come from improved haemostasis with laser ablation, reducing bleeding complications. Unfortunately, the use of lasers for endoscopic surgery has been severely limited due to the lack of a suitable flexible delivery system capable of handling the high intensities required. Through EPSRC funding we developed a new family of optical fibres that are ideally suited for laser surgery. In particular these fibres deliver wavelengths and pulse energies previously unattainable. They have a small diameter (scale of a human hair) and are highly flexible and open up new routes for minimally invasive surgical therapies where the action of the laser is required within the body. The fibres were shown to deliver infrared and ultrafast lasers with adequate power for the ablation of hard and soft biological tissue and are mechanically and chemically robust. They can be bent to very small diameters (a few mm) and significantly outperform the current state-of-art technologies for laser delivery in surgery. Additionally, new imaging techniques are emerging using molecules that specifically attach to, and mark, cancerous tissue. These marked tumours, when correctly illuminated, will fluoresce or "light-up" and stand out from healthy tissue. This is particularly useful for small, early stage, flat tumours that are not visible under standard illumination allowing them to be readily visualised aiding a precise surgical intervention. It will also facilitate complete eradication of the tumours, helping to avoid problems with tumour recurrence. Due to its precision (far exceeding that of thermal endoscopic tools) laser energy can exploit this function and accurately target tumours. Through our Healthcare Partnership we will realise the full potential of these fibres and create a novel steerable surgical tool guided by the fluorescent marker. Our partnership consists of experts in high power laser applications and biophotonics at Heriot-Watt University and clinical expertise at the University of Leeds. Renishaw Plc have strong commercial activity in medical applications and can exploit the technology and Edinburgh Molecular Imaging Ltd developed the novel fluorescence marker. Together we will exploit this technology to develop a life-saving colorectal surgical procedure transferable to other life-threatening conditions.