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A recent study found that higher-dose radiation therapy effectively kept men free from prostate cancer for 5 years. Image credit: Europa Press News/Getty Images.
  • Researchers conducted a trial in men with prostate cancer to see whether five higher doses of radiation therapy could be as effective as 20 or more lower doses.
  • While the five doses of radiation therapy exposed the men to higher doses of radiation daily, the overall amount of radiation exposure was less compared to what is administered over 20 or more doses.
  • Five doses of multibeam therapy were effective for keeping men cancer-free at their 5-year follow-up, but they also had a slight edge over the traditional 20-dose radiation therapy.

Prostate cancer affects hundreds of thousands of men in the United States yearly. According to the American Cancer Society (ACS), 1 in 8 men are diagnosed with prostate cancer over their lifetimes.

While most men respond well to cancer treatments, prostate cancer remains the second most deadly cancer for men. One available cancer treatment for men is radiation therapy, which providers typically deliver in 20 to 39 doses over several weeks.

While radiotherapy is highly effective, some researchers wonder if there is room for improvement — specifically in terms of the treatment length.

Researchers from the Institute of Cancer Research in London, United Kingdom, recently conducted the Prostate Advances in Comparative Evidence (PACE-B) study.

Their goal was to determine whether they could shorten the course of radiation therapy for prostate cancer by delivering higher multibeam radiotherapy doses.

The researchers presented their findings at the American Society for Radiation Oncology (ASTRO) conference on October 2, 2023.

During their presentation, the scientists revealed that not only was their higher-dose radiation therapy effective at keeping men cancer-free for 5 years, but it was also approximately 96% effective compared to around 95% for traditional therapy.

There are several treatments available for prostate cancer, including:

The ACS notes radiation therapy is “the first treatment for cancer that is still just in the prostate gland and is low grade.” This type of prostate cancer has not spread anywhere and is typically slower growing.

Past studies on radiation therapy in prostate cancer show that it can be 90% effective in patients where the cancer is in the early stages.

While the prognosis for prostate cancer caught early is generally positive, the researchers in the current study wanted to see if reducing treatment length was possible.

The typical course of radiation therapy treatments takes several weeks to deliver 20 or more radiotherapy doses. Cancer Research U.K. lists some side effects patients may experience during treatment:

  • tiredness and weakness that gets worse throughout treatment
  • skin pain in the treatment area that also worsens during treatment
  • difficulty with urinating during treatment.

The current study’s researchers wanted to test stereotactic body radiotherapy (SBRT), which “enables precise delivery of a higher dosage to the target area.”

The scientists recruited 874 men with a median age of 70 years with low to medium-risk prostate cancer. They randomly assigned the men to receive either SBRT or standard radiotherapy.

The researchers administered SBRT in five sessions over 1 to 2 weeks. The radiation doses were higher daily than what they administer with traditional radiotherapy, although the dose for the entire treatment regimen is lower.

The participants selected for traditional radiotherapy received their doses over the course of 4 weeks or 7.5 weeks, depending on whether they needed 20 doses or 39 doses.

After all participants received their treatments, the researchers followed up throughout the next 6 years and also checked in at the 5-year mark to see what percentage of patients were cancer-free.

“Five-year BCF [biochemical and/or clinical failure] free rates are high in PACE-B participants,” note the study authors.

While the rates were high regardless of which treatment the participants received, the ones who received their radiation doses over a shorter period had a slightly higher cancer-free rate.

Five years after receiving radiotherapy treatment, 95.7% of the patients receiving the SBRT treatments were cancer-free. Alternatively, 94.6% of patients receiving traditional therapy were cancer-free.

The authors report that side effects were minimal but that the participants who received SBRT treatments did have slightly more side effects that affected their genital or urinary organs.

Of SBRT patients with side effects, 5.5% reported grade 2 or higher side effects, while 3.2% of patients with traditional radiotherapy reported such side effects.

The authors note in their abstract that the 5-dose treatment should become the “new standard of care” for patients with cancer that hasn’t moved outside the prostate gland.

Overall, the study suggests that for individuals with low to medium-risk prostate cancer, SBRT is an effective treatment that would drastically cut down the time men have to spend going through treatments.

Dr. Asif Harsolia, board certified radiation oncologist, spoke with Medical News Today about the PACE-B study findings.

“For many patients, I think this will be a game changer in regards to the treatment of low-risk and favorable intermediate-risk patients who are candidates for this treatment,” commented Dr. Harsolia.

Dr. Harsolia said his hospital successfully uses this regimen of a higher radiation dose with a shorter treatment time.

“Like the study authors, we have found the treatment to not only be more cost-effective but also much more convenient for patients,” said Dr. Harsolia.

Dr. Harsolia is the medical director of radiation oncology at MemorialCare Cancer Institute at Orange Coast Medical Center in Fountain Valley, CA.

The doctor did mention one minor potential drawback to the higher dose regimen.

“While the larger doses can result in more temporary swelling of the prostate gland leading to what appears to be a largely transient increase in […] urinary symptoms, overall the toxicity appears to be relatively similar in patients in both arms of the study over the long term,” noted Dr. Harsolia.

Dr. Robert Wollman, a radiation oncologist and medical director of the Vasek Polak Radiation Oncology Department at Providence Saint John’s Health Center in Santa Monica, CA, not involved in the current research, also spoke with MNT about this and similar studies.

He told us:

“There is quite a bit of data, including this study from the U.K., showing that we can treat many patients with a 5-treatment SBRT regimen and get the same cure rates. Patients sometimes experience a bit more short-term urinary irritation (increased frequency or urgency) from the shorter schedule, but most do not. And when they do, the irritation only lasts for a few weeks.”

Dr. Wollman did say he would not use this regimen on patients with existing urinary issues. “I think they would be happier with a longer course of radiation and less worsening of their irritative symptoms,” he pointed out.