Safe and effective shortening of radiation therapy for men with high-risk prostate cancer

prostate cancer

Prostate cancer cells. Credit: NIH Image Gallery

A new randomized study confirms that men with high-risk prostate cancer can be treated with radiation therapy for 5 weeks versus 8 weeks. The phase III clinical trial is the first to confirm the safety and effectiveness of a moderately shortened course of radiation therapy specifically for patients with high-risk disease. Findings from the Prostate Cancer Research 5 trial (PCS5; NCT01444820) will be presented today at the American Society of Radiation Oncology (ASTRO) Annual Meeting.

“I think this trial will pave the way for high-risk prostate cancer patients to be treated for five weeks instead of eight. Many of these patients are still getting eight weeks of radiation, but try it.” Our trial found no benefit for 3 people. more weeks,” said lead author Tamim M. Niazi, MD, an associate professor of oncology at McGill University and a radiation oncologist at the Hospital. “Survival rates and side effects, both short-term and long-term, are similar with moderate short-term radiotherapy,” says the Jewish General Institute in Montreal.

Large, randomized studies have confirmed the safety and effectiveness of short-term or moderate-fractionated radiotherapy for patients with low, intermediate, or mixed-risk prostate cancer. The PCS5 trial was the first to show similar results specifically for men with high-risk disease.

“We asked, can we safely and effectively deliver radiation in a shorter time so that our high-risk patients finish treatment faster?” Dr. Niazi said. “Treatment of attenuated prostate cancer reduces the financial harm to the patient, and it is completed in 25 days instead of the usual 38 to 40 days. That’s three weeks of no visits to the clinic — a cost. transportation, parking and the time it takes away from one’s day-to-day life.”

About 15% of men diagnosed with prostate cancer are at high risk of developing the disease. These men face a higher likelihood than groups with a lower risk of the cancer coming back and/or spreading, and in those cases, they are more likely to die from their disease. The radiobiological properties of prostate cancer cells make them particularly sensitive to changes in radiation fractional size, Dr. Niazi explains. “The whole idea behind this study – delivering moderately higher doses of radiation each day combined with long-term androgen deprivation therapy (ADT) – is that we can maintain cancer control rates. prostate as with standard segmentation, but for a shorter period of time.”

In this multicenter Canadian trial, 329 patients were randomized to receive standard/conventional fractionated prostate radiation (76 Gy for 38 daily sessions) or moderately fractionated radiation (68 Gy for 25 daily sessions). Patients must have high-risk disease, as indicated by a higher Gleason score (8-10), Stage T3a or higher, or PSA above 20, to be eligible to participate in the study. All patients also received radiation therapy to the pelvic lymph nodes and long-term ADT before, during, and after radiation therapy (median duration 24 months).

Seven years after completing the course of radiotherapy, men who received reduced fertilizer or standard treatment had similar survival and recurrence rates. Comparing patients who received rapid versus standard treatment, the investigators found no difference in overall survival (81.7% vs 82%, p = 0.76). Prostate cancer-specific mortality (94.9% vs 96.4%, p = 0.61), biochemical recurrence (87.4 vs 85.1%, p = 0.69), distant metastatic recurrence (91.5% vs 91.8%, p = 0.76) or disease-free survival (86.5% vs 83.4%, p = 0.50) .

Side effects were similar between the treatment groups. There was no grade 4 toxicity in either arm, and there was no significant difference in severe short-term or long-term genital (GU) and gastrointestinal (GI) toxicity. Dr Niazi said the team was surprised that side effects were not significantly more pronounced with rapid treatment.

While most patients are at high risk prostate cancer Dr. Niazi explains that some patients may benefit from a shorter course of radiation therapy, such as those who have previously had prostate (focused therapy), distal pelvic radiotherapy for other reasons or those with active inflammatory bowel disease, among other reasons, were excluded from the trial and should still receive eight weeks of radiation therapy.

Dr. Niazi outlined several next steps for this research. One pathway involves further reduction of particle counts for patients with favorable high-risk disease, with an approach known as “aggressive reduction” likely to include only five treatments. treat. Another avenue involves enhancing hormone therapy for very high-risk patients. “We know why patients unfortunately die from cancer is due to metastasis, and the only way to reduce the rate of metastases is to increase therapy“One last option is to study biomarkers/gene alterations to determine which patients should be treated more or less aggressively,” said Dr. Niazi.

Optimizing the balance of treatments in prostate cancer

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