Long-Term Androgen Deprivation Underused for Prostate Cancer

By Scott Baltic

March 12, 2019

NEW YORK (Reuters Health) - Long-duration androgen deprivation therapy (ADT) is widely underused in men, especially African Americans, who are undergoing definitive external beam radiotherapy (EBRT) for high-grade prostate cancer, a new U.S. study has found.

Nearly a quarter of patients in the population-based retrospective trial received no long-term ADT, and fewer than one in seven received the recommended 24 to 36 months.

"Overall, this underutilization is concerning, as multiple randomized controlled trials have confirmed a survival benefit to longer durations of concomitant ADT, and thus long-term ADT constitutes the current standard of care," Dr. Amar Kishan of the University of California, Los Angeles, and his colleagues write in European Urology Oncology, online February 1.

"I think a lot of individuals would be surprised to know that ADT is so commonly being underutilized," Dr. Kishan added in an email to Reuters Health. "That is troubling, and the racial aspect even more so."

The study examined records from the Surveillance, Epidemiology, and End Results (SEER) Medicare-linked database of non-Hispanic white and African-American men with Gleason grade group 4-5 (Gleason score 8-10) prostate cancer treated definitively with EBRT from 2008 to 2011.

In all, 961 men (852 white and 109 African-American) were included in the study. Significant differences at baseline in all covariates between AA and NHW men were largely reduced after adjustment via propensity score.

Men were excluded if they had more than one primary malignancy, positive lymph node involvement, or metastasis at diagnosis; underwent orchiectomy or ADT not coded as a gonadotropin-releasing hormone agonist; started ADT more than six months prior to the start of radiotherapy, or received consecutive ADT for more than 36 months.

Of the participants, 23.4% received no ADT, 30.9% received one to six months of treatment, 32.6% seven to 23 months and 13.1% received 24 to 36 months.

Use of ADT differed between African-American and non-Hispanic white men, with 33.9% versus 22.1% receiving no ADT, respectively. This difference was significant even after adjusting for covariates.

This racial disparity "is consistent with recent reports of disparities in the delivery of definitive treatments" in African-American men versus non-Hispanic white men and could, in part, explain the inferior prostate cancer-specific mortality outcomes reported for African-American men, the authors write.

"While it is certainly possible that a fair number of patients had cardiac or other comorbidities that led to a medical decision to decrease the duration of ADT, the degree of underutilization is quite significant and unlikely to be wholly explained by this limitation," they add.

"More training on the clear survival benefit of longer-term ADT, and training on minimizing the side effects, may be helpful," Dr. Kishan said. "An alternative approach, which is also ongoing, is trying to learn how to decrease the duration of ADT without compromising survival."

Dr. Ronald C. Chen, associate professor and associate chair for education with the department of radiation oncology at the University of North Carolina at Chapel Hill, told Reuters Health by email that "there are now multiple studies consistently showing underutilization of ADT in patients with high-risk prostate cancer treated with EBRT. This is very concerning."

"While ADT does have side effects, as all cancer treatments do, patients need to be informed that long-duration ADT improves cure rates and prolongs life, as demonstrated by multiple clinical trials," he continued. "Therefore, skipping ADT, or giving short-duration instead of long-duration ADT, for these patients with the most aggressive form of localized prostate cancer, has significant potential negative consequences."

"Further research is needed to better understand if patients are deciding not to receive ADT, or physicians are recommending against ADT," said Dr. Chen, who was not involved in the study. "I suspect there is some of both."

In an email to Reuters Health, Dr. Quoc-Dien Trinh, co-director of the prostate-cancer program at Dana-Farber/Brigham and Women’s Hospital in Boston and assistant professor of surgery at Harvard Medical School, called the racial disparity "a notable finding."

"Many investigators (including myself) feel that the racial differences in prostate-cancer outcomes have more to do with access to quality care rather than biological differences," he explained. "To show that African-American men are under-treated for potentially lethal prostate cancer supports that hypothesis."

"Patients need to be aware of the importance of ADT in conjunction with EBRT for high-risk prostate cancer," said Dr. Trinh, who also was not part of the study. "Policy makers should devise strategies to incentivize physicians (or hospitals) to provide high-quality care to ALL men with prostate cancer."

SOURCE: https://bit.ly/2F3cEJl

Eur Urol Oncol 2019.

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