Metastasis-Directed Therapies May Lead to a Delay in Disease Progression for Some Patients With Prostate Cancer

Metastasis-directed therapies may be effective in prolonging survival and delaying treatment with systemic therapies such as androgen-deprivation therapy in patients with oligometastatic prostate cancer, according to findings from a recent study.

“This study continues to highlight a potential for metastasis-directed therapy in patients with oligo-recurrent prostate cancer and may allow patients to delay initiation of hormones,” said Dr. Jack R. Andrews, lead author on the study, in an interview with CURE®. “And in select patients, it's yet to be seen, but there may be a more durable response to metastasis-directed therapy.”

Oligometastatic prostate cancer is an intermediate stage between localized and metastatic disease. Some experts suggest a combination of local and metastasis-directed therapies may be an effective form of treatment, although some experts disagree with that approach.

“There’s a lot of controversy regarding (metastasis-directed therapies’) role,” said Andrews, who is a urologist at the Mayo Clinic in Phoenix. “And a lot of people will argue that there’s no role for it or it doesn’t have a benefit. It’s kind of hard to prove in this setting that is should be utilized.”

Andrews and researchers sought to answer the question if metastasis-directed therapies are effective by evaluating it in patients who were most likely to respond — those with recurrent disease and a solitary metastatic lesion.

The study, which was published in The Journal of Urology, included 124 patients with oligometastatic prostate cancer, of which 67 were treated with surgery and 57 received stereotactic body radiation therapy. Both groups of patients also received metastasis-directed therapy.

“If these patients didn't respond to metastasis-directed therapy or didn't have any improvement in progression-free survival (or) delay in androgen deprivation (therapy), then that would be a nail in the coffin for metastasis-directed therapy,” he noted.

Of patients who underwent surgery, 80.5% had more than a 50% decline in their prostate specific antigen at first follow-up. Additionally, progression-free survival (time during and after treatment when the patient lives without disease progression) was 29% and median time to systemic therapy was 18.5 months.

For those who received stereotactic body radiation therapy, 40.3% had more than a 50% decline in their prostate specific antigen at first follow-up with a progression-free survival rate of 17%. In addition, these patients had a median time to systemic therapy of 17.8 months.

“As we suspected — and seen clinically — there are a subset of patients that do have a fairly significant response and it kind of leaves the door open for further investigation and clinical trials in the metastasis directed therapy space,” Andrews noted.

The important part for patients is the delay in androgen deprivation therapy because of its significant impact on quality of life, he added. Patients on androgen deprivation therapy may experience significant fatigue, loss of libido and feeling unwell.

“So the delay in androgen deprivation will certainly delay that decline in their quality of life,” Andrews said. “And then our hope is that at some point, it can be shown in clinical trials that delaying hormone therapy with effective metastasis-directed therapy will ultimately delay castration resistance, which is (when) you start to develop lethal prostate cancer.”

The field of advanced prostate cancer is progressing, he continued, and studies such as this can provide hope to patients that there are potentially more treatments on the horizon.

“I think for patients, it gives hope in the future that these (therapies) … have the potential to become more widespread in our armamentarium and that some patients will have significant response and delay in (disease) progression and androgen deprivation,” Andrews concluded.

For more news on cancer updates, research and education, don’t forget to subscribe to CURE®’s newsletters here.