To get rid of the cancer cells or to let them be? That is the question men must grapple with when diagnosed with early-stage prostate cancer. While the risk it presents is minimal, the side effects of radical treatments designed to get rid of these low-grade cells are not and often cause far more damage than anticipated. For patients who would rather not risk these devastating side effects, there is active surveillance. As for those who would rather not live with the worry that their cancer might one day metastasize, there might be good news on the horizon: researchers in the UK have announced a new laser therapy treatment that can kill tumor cells without inflicting collateral damage on healthy tissue or the patient's lifestyle.
Called Vascular-Targeted Photodynamic therapy (VTP), the new treatment is administered by injecting a light-sensitive drug, called WST11, into the bloodstream via fiber lasers that are inserted into the prostate gland. The laser then activates the drug to destroy the tumor tissue. Interestingly, WST11 is derived from deep-sea bacteria that have evolved a mechanism to survive in the dark by efficiently converting whatever little light it can get into energy. Researchers were able to develop a compound that releases free radicals to kill cancer cells when activated by laser using this property.
There are a few things worth noting about this treatment, which involved 47 treatment sites from ten European countries: Firstly, according to the study, 49 percent of the 413 men who underwent treatment went into "complete remission" compared with 13.5 percent in the control group. Secondly, only six percent of VTP patients ended up needing radical therapy, compared with 30 percent in the control group who were under active surveillance. In the case of the former, the chances of the cancer becoming dangerous were three times lower, with the average time to progression doubling from 14 to 28 months. Thirdly, while VTP did cause urinary and erectile problems, these were short-term side effects that were resolved within three months. In comparison, radical therapy often results in long-lasting impotence and incontinence.
Lead investigator Mark Emberton, a urologist at University College London Hospitals, describes the results of this phase III clinical trial as "a huge leap forward" given that treatment of the disease has often trailed other cancers such as breast cancer.
"In 1975 almost everyone with breast cancer was given a radical mastectomy, but since then treatments have steady improved and we now rarely need to remove the whole breast. In prostate cancer we are still commonly removing or irradiating the whole prostate, so the success of this new tissue-preserving treatment is welcome news indeed," he says, adding that advances in technology have made it easier to develop more targeted therapies.
"We can now pinpoint prostate cancers using MRI scans and targeted biopsies, allowing a much more targeted approach to diagnosis and treatment," says Emberton. "This means we could accurately identify men who would benefit from VTP and deliver treatment more precisely to the tumor. With such an approach we should be able to achieve a significantly higher remission rate than in the trial and send nearly all low-risk localised prostate cancers into remission."
On another note, while the therapy was developed to treat prostate cancer, there is no reason it cannot be adapted to treat other diseases such as breast and liver cancer, he adds.
In any case, at least one trial patient is more than satisfied with the treatment he has received. Sixty-eight-year-old Gerald Capon says the treatment "changed [his] life," explaining that he opted for it because he didn't want to "live with the fear of the cancer spreading until it either couldn't be treated or needed a treatment that would stop me living a normal life." Now cancer-free with no side effects, he says he can go about his life without worrying about needing surgery in future.
John Lewis, an associate professor in experimental oncology at the University of Alberta who was not involved in the study, believes this treatment could certainly give men diagnosed with early-stage prostate cancer a better peace of mind. "The problem with being on active surveillance is that you need to be on repeated PSA (prostate specific antigen) tests, and these potentially include repeated biopsies, which are very invasive," he tells New Atlas. The VTP treatment would quell unease by providing a way to get rid of a low-risk cancer with minimal side effects. Though not completely non-invasive – the laser light can only be administered through needles – there is the possibility of doing an imaging-guided version of the treatment, i.e. an MRI, he adds.
On the other side of the spectrum, there are some medical practitioners who remain skeptical about the purported benefits of VTP. Ola Bratt, a prostate cancer surgeon at Cambridge University Hospitals, points out that the risk of dying from low-risk prostate cancer if left untreated is less than five percent. In light of this, is getting rid of these low-grade cancer cells really worth it? "All men were diagnosed with low-grade cancer, which we today know is indolent and should not be treated, so even if some of the men got rid of their low grade cancer cells it would make little clinical difference," he tells New Atlas, adding that the claims of remission are debatable given that prostate biopsies are not an accurate method of ruling out small foci of prostate cancer. "Two years after VTP, 12 percent still had potentially progressive cancer in their biopsies and we know that routine biopsies may miss as many cancers as they sample." All these raise the question of how VTP might help men with a potentially lethal cancer.
That said, whether or not VTP represents overtreatment of a low-risk cancer is open to debate, however the fact that it gives patients another option – and more importantly one that has been shown to have no long-term adverse effects on their quality of life, something that new experimental drugs and non-invasive clinical trial treatments such as Stereotactic Body Radiation Therapy cannot claim to offer – should not be overlooked.
The treatment, which was developed at the Weizmann Institute of Science in Israel in collaboration with STEBA Biotech, is currently under review by the European Medicines Agency.
Results of the study were published in The Lancet Oncology.
Source: UCL
