Cumulative evidence to date supports the implementation of stereotactic body radiotherapy — a highly precise radiation therapy delivered in shorter periods of time — as a standard treatment for people with localized prostate cancer, a study shows.
The study, “Stereotactic Body Radiotherapy for Localized Prostate Cancer: A Systematic Review and Meta-Analysis of Over 6,000 Patients Treated On Prospective Studies,” was published in the International Journal of Radiation Oncology.
Prostate cancer is the most common cancer diagnosed in men in the U.S.and is a big component of the yearly healthcare expenditure.
External beam radiotherapy, a method that involves delivering radiation beams to a patient’s tumor, is an effective treatment for men with localized prostate cancer. Traditionally, this type of radiotherapy was delivered in small daily doses over eight to nine weeks to spare the healthy tissues adjacent to the tumor.
However, a serious drawback to this approach is the number of times the person has to undergo radiotherapy. That not only increases healthcare costs, but also creates a greater burden and challenge for patients.
Over the last 20 years, with technological advances, treatments have significantly improved. In particular, the emergence of a type of radiotherapy known as stereotactic body radiotherapy (SBRT), allows treatment in just four to seven sessions.
SBRT works by giving radiotherapy from many different angles around the body. The beams meet at the tumor, hitting it with a high dose of radiation, while the tissues around it receive a much lower dose.
Optimization of this technique over the last few decades has led to the incorporation of SBRT into routine clinical practice. In fact, SBRT is now a standard of care treatment option for many different types of tumors.
Despite the plethora of clinical trials that support SBRT, however, some organizations have yet to update their guidelines to support the adoption of SBRT for treating prostate cancer.
That led researchers to conduct a systematic review and meta-analysis of all published prospective studies to assess the outcomes following prostate cancer SBRT.
The team found 38 unique prospective studies that included a total 6,116 patients — 92% low risk, 78% intermediate risk, and 38% were high risk. The median follow-up for all patients was 39 months.
Investigators examined the time it took for participants to experience a biochemical recurrence — deemed as a rise in PSA levels — after SBRT. They found that, after five years, 95.3% of patients remained without any signs of cancer recurrence, and 93.7% reached the seven-year mark free of cancer recurrence.
Very few patients experienced acute severe side effects (fewer than 1%) or long-term severe side effects (2% for genitourinary and 1.1% for gastrointestinal toxicity rates).
While treatment worsened the patients’ bowel and urinary functions, these returned to baseline levels within a 2-year period. Sexual function, however, continued to worsen with time, reaching a statistically significant difference three years after treatment.
Researchers lastly showed that, while increasing the dose of SBRT increased the time patients lived without a biochemical recurrence, it also increased the rates of late severe genitourinary toxicity.
“We herein demonstrate that there is considerable evidence that prostate SBRT is an effective treatment for localized prostate cancer, with a very favorable toxicity profile that has minimal impact on long-term urinary and bowel quality of life,” the investigators said.
“Our findings support that SBRT could be considered a standard radiotherapeutic strategy for localized prostate cancer, while ongoing trials assess its potential superiority to other treatment methods,” they concluded.
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