The study offers a combination treatment option for patients with oligometastatic prostate cancer

The study offers a combination treatment option for patients with oligometastatic prostate cancer

A new study offers a new option for patients with oligometastatic prostate cancer who want freedom from hormone therapy without the risk of spreading their disease. In the study, patients who received radiation in addition to intermittent hormone therapy lived longer without their disease progressing and were able to take longer breaks from drug treatments. Results from the Phase II trial (EXTEND; NCT03599765) will be presented today at the American Society for Radiation Oncology (ASTRO) Annual Meeting.

This study is the first randomized trial to evaluate the effects of adding radiation to hormonal therapy in patients with oligometastatic prostate cancer -; That means those whose cancer has spread to five or fewer lesions or metastases throughout the body.

Because most prostate cancer cells rely on testosterone to grow, standard treatment typically involves therapy to deplete the body of the hormone. A growing number of studies indicate that local therapies such as radiation and surgery in combination with hormone therapy can improve outcomes for patients with oligometastatic disease, and the EXTEND study is the first to demonstrate this in a randomized clinical trial.

The use of radiation for oligometastatic prostate cancer can result in excellent tumor control and good long-term outcomes and allows us to give these patients long breaks from hormone therapy.”

Chad Tang, MD, lead author of the study and associate professor of radiation oncology, The University of Texas MD Anderson Cancer Center at Houston

Hormone therapy is an effective way to prolong survival in patients with metastatic cancer, but it often causes serious side effects, said Dr. Tang. Depletion of testosterone can lead to lack of energy, impotence and hot flashes - what might be called "male menopause" - as well as an increased risk of cardiovascular disease, osteoporosis and mental disorders.

EXTEND is a basket study enrolling adults with five or fewer metastases from different types of solid tumors. The study by the team of Dr. Tang is the primary analysis of the prostate basket, which included 87 participants receiving intermittent hormone therapy for prostate cancer. These patients were randomized to hormone therapy with either (n=43) or without (n=44) local therapy. Local therapy options included radiation, surgery, or cryotherapy to any site of oligometastatic disease; All men in the study received radiation therapy.

eBook on laboratory diagnostics and automation

Compilation of the top interviews, articles and news from the last year. Download a copy today

Patients received hormone therapy for at least two months before starting the study, and each participant stopped hormone therapy six months after starting the study for a planned break. The patients began hormone therapy again as their disease progressed.

Researchers tracked the length of time until patients showed signs that their cancer had progressed, such as: B. rising PSA level. They also measured the time that patients maintained normal testosterone levels after treatment before they had to restart hormone therapy.

The median follow-up time was 22.1 months, and during this time the cancer progressed in 41 patients. Those who received both local therapy and hormone therapy had longer progression-free survival (median not reached vs. 15.8 months with hormone therapy alone; HR 0.25, 95% confidence interval 0.12-0.55, p < 0.001).

Fewer patients in the combination arm had new lesions two years after treatment (33% vs. 41%, p = 0.004). Patients in the combination arm also had normal testosterone levels for longer than those who did not receive local therapy (p = 0.03). Three serious (ie, Grade 3) adverse reactions were observed in each treatment group.

The "potent synergy" between radiation and hormone therapy could be the key to the success of the combined treatment, said Dr. Tang. "In several studies, hormone therapy has been shown to work synergistically with radiation therapy to reduce the ability of prostate cancer cells to repair themselves after radiation-induced DNA damage," he explained.

In addition to the clinical results, the research team also examined the immune-stimulating effects of radiation. “In our study, we saw increased T-cell activation and other signals of greater immune activity in patients in the combined therapy arm, but not in the hormone therapy-only arm.”

After a patient's prostate cancer metastasizes, they typically receive continuous hormone withdrawal. Dr. Tang said this study introduces a new paradigm of definitive radiotherapy for all oligometastases in a patient in conjunction with de-escalated, intermittent hormone therapy to preserve quality of life while maintaining disease control.

Source:

American Society for Radiation Oncology

.