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Effect of Timing of Radiotherapy Relative to ADT on Overall Survival in Prostate Cancer

Potential Implications for Treatment During the COVID-19 Pandemic


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In a study reported in JAMA Oncology, Dee et al found that radiotherapy (RT) initiated at up to 6 months after the start of androgen-deprivation therapy (ADT) was not associated with poorer overall survival vs initiation before ADT in men with prostate cancer. The investigators observed that these findings suggest that delay of RT constitutes an option in the setting of treatment during the COVID-19 pandemic.

As stated by the investigators, “[The] COVID-19 pandemic poses challenges for patients with localized prostate cancer who require …RT, often administered with 6 to 36 months of … ADT. Daily hospital trips for RT create many possible points of COVID-19 transmission, and patients with cancer are at high risk of COVID-19 mortality…. Therefore, an important option for patients being treated with RT and ADT is delayed RT initiation.”

Study Details

The study involved data from the National Cancer Database for 2004 to 2014 on 63,858 patients with unfavorable intermediate-risk and high-risk or very high–risk disease who received external-beam RT and ADT. Multivariate analysis of 10-year overall survival according to RT start times relative to ADT initiation was adjusted for Gleason score, prostate-specific antigen level, T stage, race, age, year of diagnosis, facility type, region, county type (rural or urban), distance traveled to the treatment facility, Charlson-Deyo comorbidity score, insurance status, and zip code median household income.

Key Findings

RT start times were categorized as: RT 0 to 60 days before ADT initiation (reference group; n = 3,572); RT 1 to 60 days after ADT initiation (n = 23,207), RT 61 to 120 days after ADT initiation (n = 30,285), and RT 121 to 180 days after ADT initiation (n = 6,794).

KEY POINTS

  • Later RT initiation up to 6 months after ADT initiation was not associated with worse overall survival vs initiating RT before ADT.
  • The findings possibly justify the delay of prostate RT for patients currently receiving ADT during the COVID-19 pandemic.

Among 19,258 men with unfavorable intermediate-risk disease (4,220 total deaths), 10-year overall survival rates were 59.2% with RT initiated 0 to 60 days before ADT initiation, compared with 57.9% with RT 1 to 60 days after ADT initiation (hazard ratio [HR] = 1.03, P = .64), 62.3% with RT 61 to 120 days after ADT initiation (HR = 0.95, P = .42), and 58.9% with RT 121 to 180 days after ADT initiation (HR = 0.99, P = .90).

Among 44,600 men with high- or very high-risk disease (10,959 total deaths), 10-year overall survival rates were 58.9% with RT initiated 0 to 60 days before ADT initiation, compared with 51.7% with RT 1 to 60 days after ADT initiation (HR = 1.07, P = .12), 54.8% with RT 61 to 120 days after ADT initiation (HR = 1.04, P = .36), and 52.4% with RT 121 to 180 days after ADT initiation (HR = 1.07, P = .17).

When modeled continuously and nonlinearly, date of RT initiation was not associated with overall survival.

The investigators concluded: “Based on analysis of a large database of patients with unfavorable intermediate-risk, high-risk, or very high–risk [prostate cancer], later RT initiation up to 6 months after ADT initiation was not associated with worse [overall survival] compared with initiating RT before ADT. These results validate the findings of 2 prior randomized trials … and possibly justify the delay of prostate RT for patients currently receiving ADT until COVID-19 infection rates in the community and hospitals are lower.”

Vinayak Muralidhar, MD, Department of Radiation Oncology, Dana-Farber Cancer Institute/Brigham and Women’s Hospital, Harvard Medical School, is the corresponding author for the JAMA Oncology article.

Disclosure: The study was funded by a grant from the National Institutes of Health. For full disclosures of the study authors, visit jamanetwork.com.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
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