Prostate Cancer More Likely to Metastasize With Active Surveillance

September 16, 2016

While survival at 10 years was nearly identical (close to 99%), a new study found that localized prostate cancer is more likely to metastasize in men receiving active surveillance compared with those who have surgery or radiation therapy.

While survival at 10 years was nearly identical (close to 99%), a new study found that localized prostate cancer is more likely to metastasize in men receiving active surveillance compared with those who have surgery or radiation therapy. These results were published in the New England Journal of Medicine.

“The results show that death from prostate cancer in such men remained low at a median of 10 years of follow-up, at approximately 1%, irrespective of the treatment assigned, a rate that is considerably lower than was anticipated when the trial commenced,” wrote study authors led by Freddie C. Hamdy, MD, professor of surgery and neurology at the University of Oxford in England. “All-cause mortality was also low-at approximately 10%.”

The PROTECT (Prostate Testing for Cancer and Treatment) trial randomized 1,643 men between the ages of 50 and 69 to active surveillance (n = 545), surgery (n = 553), or radiotherapy followed by androgen-deprivation therapy (n = 545). At 10 years follow-up there have been 17 reported deaths due to prostate cancer (5 in the surgery arm, 4 in the radiotherapy arm, and 8 in the active surveillance arm); the difference in prostate cancer–specific deaths among the three patient groups was not significant (P = .48).

In addition, no significant difference was seen in all-cause mortality among the three groups (169 deaths overall; P = .87).

For prostate cancer patients with low- or intermediate-risk disease, this is the first long-term trial that compares the current options for initial care-surgery, radiation therapy and androgen-deprivation therapy, or active surveillance with prostate-specific antigen (PSA) testing and treatment upon progression.

Incidence of metastasis was more than twice as high in the active-monitoring group (33 men) compared with the surgery (13 men) and radiotherapy (16 men) groups (P = .004 for the overall comparison).

“The clinical significance of this finding is that with the use of active monitoring, more men will have metastasis and the side effects of salvage treatment (meaning at least lifelong intermittent androgen-deprivation therapy), which are not inconsequential,” wrote Anthony V. D’Amico, MD, PhD, chief of genitourinary radiation oncology at the Brigham and Women’s Hospital and Dana-Farber Cancer Institute in Boston, in an accompanying editorial.

There was also a trend toward decreased death from prostate cancer in the group of men who underwent surgery compared with those followed with active surveillance (hazard ratio, 0.63), noted D’Amico, and there were higher rates of disease progression in the active surveillance group (112 men) compared with the surgery and radiotherapy groups (46 men in each; P < .001 for the comparison overall).

While the trial is ongoing to analyze whether the trends observed at study year 10 will become statistically significant, “for today, we can conclude on the basis of Level 1 evidence that PSA monitoring, as compared with treatment of early prostate cancer, leads to increased metastasis,” D’Amico added.

In a separate publication, researchers led by Jenny L. Donovan, PhD, of the School of Social and Community Medicine at the University of Bristol in England, analyzed patient reported outcomes, finding that prostatectomy resulted in the most adverse effects on sexual function and urinary continence. All three study arms had similar rates of anxiety, depression, and general health-related and cancer-related quality of life outcomes. This detailed outlook of adverse events should allow patients and clinicians to make informed decisions for an individual’s best course of therapy.