4509 Laser therapy of colorectal cancer:is there a role for photodynamic therapy?

Abstract

Laser therapy of colorectal cancer (CRC) may be used to maintain a luminal patency and to relieve local complications of bleeding and mucus discharge. The effectiveness of potassium titanyl phosphate (KTP)laser therapy in controlling the symptoms of 1) obstruction due to CRC and 2)frequent mucus and blood discharge due to recurrence of cancer in a rectal stump post Hartmann's procedure was evaluated. Results: 1) Ten patients with CRC obstructing the lumen were treated with a KTP laser which was set to 15 mW to ablate the tumour tissue. In nine patients the treatment was successful with the resolution of abdominal symptoms and the maintenance of bowel movements. The number of treatments varied from 1-6, (mean of 3)and were administered approximately 1-2 months apart. In one patient, who was not treated for 3 months, the lumen became completely obstucted and so precluded laser therapy. The treatments were well tolerated; no complications occurred and patients were well palliated. 2) Twelve patients with a severe and disabling urgency and a frequency of blood and mucus discharge due to recurrence of cancer within the rectal stump were treated with KTP laser set to coagulation settings of 5 mW. Patients required 1-6 treatments (mean of 2)which were performed 1-3 months apart. In six patients a very significant improvement of symptoms was achieved; in the other six there was minimal or no improvement. There were no laser-related complications in this group. The success of the treatment was related to the ability to use the laser in an en face position in order to coagulate a significant surface area of the cancer. In one patient who had an extensive tumor within the rectal stump and who did not respond to laser treatment, Photodynamic therapy (PDT) was performed, using porfimer sodium as a sensitizer. The laser light at 630 nm was delivered via a 5 cm long fibre optic cylindrical diffuser. This patient experienced an excellent response with a resolution of a previously very symptomatic discharge. The response was rapid in onset and of long duration (6+ months follow-up). KTP laser treatment is a useful alternative to diverting colostomy and stent insertion in patients with a partially obstructive CRC; it may provide a worthwhile and safe palliation in patients who present with a recurrence of cancer within a rectal pouch. In patients where adequate laser therapy is not possible, PDT may represent a new and successful therapeutic approach. Therefore,further trials of PDT in the palliation of colorectal cancer are indicated.