Los Angeles | Scientists have found that the precise application of laser heat can safely treat prostate cancer without causing adverse effects or changes in urinary or sexual function, an advance that may lead to a safe and feasible way to treat the disease.
The technique uses magnetic resonance imaging (MRI) to guide the insertion of a laser fibre into cancerous tumours. When heated, the laser destroys the cancerous tissue. A follow-up study showed the potential to transfer this treatment for the first time into a clinic setting, using a special device (Artemis) that combines both MRI and ultrasound for real-time imaging.
If the laser technique, known as MRI-guided focal laser ablation, proves effective in further studies – especially using the new MRI-ultrasound fusion machine – it could improve treatment options and outcomes for men treated for such cancers, said Leonard Marks, a professor at the University of California, Los Angeles in the US.
Historically, prostate cancer has been treated with surgery and radiation, which can result in serious side effects such as erectile dysfunction and urinary incontinence.
Our feeling was that if you can see prostate cancer using the fusion MRI and can put a needle in the spot to biopsy it, why not stick a laser fibre in the tumour the same way to kill it, Marks said. This is akin to a lumpectomy for breast cancer.
Instead of removing the whole organ, target just the cancer inside it. What we are doing with prostate cancer now is like using a sledgehammer to kill a flea, he said. Up until now, capturing an image of a prostate cancer has been difficult because prostate tissue and tumour tissue are so similar. Precise, non-invasive surgical treatment has proved difficult as a result.
The new study shows that MRI improves the ability of physicians to perform precise, laser-based treatment. The new fusion-imaging method improves it even further, providing real-time ultrasound that more clearly delineates the tumour. By combining laser ablation with this fusion-imaging technique, the potential of laser ablation grows enormously.
For the study, eight men underwent ablation while in an MRI machine. Although none had serious side effects, longer-term follow-up is needed, as is a continued assessment of appropriate treatment margins to ensure cure, the researchers said.
The second study tested the fusion-MRI procedure on 11 men in a clinical setting. That study found the procedure was well-tolerated under local anesthesia and resulted in no side effects.
At four months follow-up, there were no changes in urinary or sexual function. This focal therapy provides a middle ground for men to choose between radical prostatectomy and active surveillance, between doing nothing and losing the prostate, Marks said.
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