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According to British researchers, treating men with low-risk prostate cancer with a single high dose of radiation can be safe and effective.
Prostate cancer treatment usually involves low-dose radiation administered over several days or weeks. Conversely, high-dose radiation is administered once through a set of tiny tubes inserted directly into the tumor.
Potentially dangerous
"For low-risk patients, a single dose of high-dose radiation is sufficient, but for patients at medium or high risk, a single dose of 19 Gy is not enough, they will probably need a higher dose. strong multiple doses, "said lead researcher Hannah Tharmalingam. She is a clinical research fellow at the Mount Vernon Cancer Center in Northwood, England.
According to Tharmalingam, high-dose radiation may be more practical for low-risk, shorter, and less expensive patients in the medical system.
But a radiation oncologist fears that its side effects make it potentially dangerous.
For the study, Tharmalingam and colleagues treated 441 prostate cancer patients between 2013 and 2018. The cancers were clbadified as low, medium or high risk.
All men were treated with a high dose of 19 Gy radiation, which is equivalent to the total amount of radiation administered over several days with current treatments, said Tharmalingam.
In addition, 166 men also received hormonal treatment. None of the men, however, have undergone surgery or chemotherapy.
Not enough after three years
For comparison, men with prostate cancer normally receive about 2 Gy of radiation in several sessions. Low dose radiation is administered to minimize side effects.
Over a 26-month period, researchers measured prostate specific antigen (PSA) levels in men, indicating the effectiveness of treatment. If PSA levels increase, it may mean that the cancer has returned.
After two years, 94% of the men remained without cancer. In men with low-risk cancer, it was 100%; in men at average risk of disease, it was 95%; and in men with high-risk cancer, it was 92%.
But after three years, this dose of radiation was not enough for patients with moderate to high risk cancer, Tharmalingam said.
After three years, 88% of men remained free of cancer. Specifically, 100% of men with low-risk cancer, 86% of those with moderate-risk cancer and 75% of those with high-risk cancer remained without cancer .
Of the 27 men whose PSA rates increased, 25 had their cancer return. The researchers found that the cancer had returned in 15 cases in the prostate and in other cases, it had spread to other parts of the body.
Experiment with higher doses
When men were treated, no serious side effects occurred. Later, however, two men had stenosis of the urethra that could prevent urination and surgery, and two patients developed a rectal fistula requiring an operation called colostomy.
Tharmalingam said that to improve the results of high single dose radiation in men with a medium or high risk cancer, other groups are experiencing radiation doses of up to 23 Gy.
But for these patients, it may be better to start giving smaller doses over a longer period of time, Tharmalingam said.
Dr. Anthony D & # 39; Amico, professor of radiation oncology at Harvard Medical School in Boston, does not think that high-dose radiation is safe. D'Amico was not involved in the new study but was aware of the results.
"This single dose of radiation is very convenient and very well thought to kill cancer," he said. "But there's no way around the stumbling block, which is just three years behind."
A three-year follow-up in prostate cancer makes very little sense as it does not indicate what will happen in the long run, said Dr. Amico.
Concerns for safety
The side effects seen in some patients, namely urethral strictures and rectal fistulas, were even more troubling, he said.
"These are unheard-of complications in the world of radiation therapy at this time," said Dr. Amico. "You do not see them anymore because these effects result from too much high doses."
These side effects can take years to manifest themselves. Seeing some patients develop them so early is very worrying, he explained.
"I would be very careful about this approach and I would not recommend it," said Amico. "I'm worried about safety – and it's not something that's safe."
The results should be presented Monday at the meeting of the European Society of Radiotherapy and Oncology, in Milan. Research presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.
Image credit: iStock
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