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17 Jun 2002
Photodynamic therapy looks like a promising treatment for pancreatic cancer.
In a world first, UK researchers report the use of photodynamic therapy to treat pancreatic cancer. By placing optical fibers in direct contact with the tumours, laser light is delivered directly to the site causing a reduction in the tumour volume (Gut 50 549).
Cancer of the pancreas is notoriously difficult to treat as it is close to vital organs, such as the stomach and duodenum, as well as major blood vessels. Few pancreatic cancers are suitable for surgery or respond to chemotherapy and as a result it is one of the top-ten leading causes of cancer-related deaths worldwide.
The team says that their promising preliminary results justify larger trials to test the approach either as a single therapy or in combination with traditional treatments such as chemotherapy.
The technique, known as interstitial photodynamic therapy (PDT), uses optical fibers to guide laser light directly into the tumour containing the light-sensitive drug. When the laser light interacts with the drug, in this case a drug called Foscan was used, a highly reactive form of oxygen called singlet oxygen is produced which results in localized cell death.
The team used optical fibers with a 400 µm core to guide the laser light into the tumour. Treatment was administered using a diode laser operating at 652 nm and delivering 100 mW per fiber.
Lead researcher Stephen Bown, based at the National Medical Laser Centre in London, explained: "Up to six needles were inserted into the deepest part of the tumour. A fiber was then passed down each needle leaving 3 mm of bare fiber in direct contact with the tumour during delivery of the therapeutic light."
The researchers guide the needles into the tumours using both ultrasound and CT scans. The fiber tips are separated by approximately 15 mm to give an even treatment distribution.
Sixteen patients were involved in the preliminary study. "The survival figures look encouraging but the true influence of PDT on survival can only be established in a randomised, controlled study," said Bown. "In our study, the volume of necrosis around individual fiber sites (averaged for individual patients) ranged from 1.4 to 5.1 cm3," he added.
The team plans to carry out further trials of this technique for pancreatic cancer. They have also carried out unpublished work on prostate cancer that recurred after radiotherapy.
Author
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.
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