Adding it to radiotherapy for patients with high-risk prostate cancer even benefits men older than 70

BOSTON—Age alone should not matter when deciding whether to combine long-term androgen deprivation therapy (ADT) and radiation therapy in men with high-risk prostate cancer, a study found.

In a retrospective study, researchers identified 530 men (median age 69 years; range 45-89 years) who had clinically localized prostate cancer with clinical signs of high-risk disease: pretreatment PSA levels of 20 ng/mL or greater, Gleason scores 8-10, or larger tumors palpable during digital rectal examination. The men had a median serum PSA level of 21 ng/mL. The median follow-up was 85 months (range 26-206 months).

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The cumulative incidence of biochemical failure—defined as a PSA rise of 2 ng/mL above nadir—was lower in men receiving ADT than in those not receiving it (21% vs. 47% in men aged 70 years and younger and 15% vs. 32% in men older than 70 years). The five-year incidence of distant metastases in men aged 70 and younger was significantly lower in ADT patients (3.7% vs. 11.8%); in men older than 70, the incidence was similar in the ADT and no-ADT groups.

This translated into a five-year overall survival advantage in men aged 70 years and younger (96% for ADT vs. 91% for no ADT) but not for men older than 70 years (89% vs. 86%). The researchers said this may be explained in part by a trend toward greater pre-existing cardiovascular morbidities in men older than 70 years who received ADT.

For all men in the study, longer duration of ADT (more than 12 months) was associated with a five-year overall survival rate of 98% compared with 87% for shorter duration (less than 12 months). Among men older than 70, the rates were 98% and 80%, respectively. In this group, shorter duration of ADT was associated with an 80% increased risk of all-cause mortality.

“We know the risks of distant metastasis, recurrence, and death are higher when androgen deprivation therapy is not part of radiation treatment,” said study investigator Joshua Silverman, MD, PhD, a radiation oncology resident at Fox Chase Cancer Center in Philadelphia, who presented the findings at the American Society for Therapeutic Radiology and Oncology annual meeting.

“We wanted to see if age should be a determining factor for treatment with hormone suppression.” He reported findings here at the American Society for Therapeutic Radiation Oncology annual meeting.

The investigators concluded that adding ADT to radiotherapy improves biochemical failure rates in men over age 70 even after accounting for competing death risks.

Although age alone should not contraindicate use of ADT in combination with radiotherapy, “we still need to be cautious with men who have multiple, known cardiovascular risk factors,” Dr. Silverman said.

He pointed out, however, that the study did not address the impact that the adverse effects of ADT, such as muscle loss, cognitive impairment, loss of libido, and osteoporosis, may have on patients’ quality of life.