Radiotherapy delays may not adversely affect prostate cancer OS
medwireNews: Starting radiotherapy up to 6 months after androgen deprivation therapy (ADT) may be feasible for men with intermediate- and high-risk localized prostate cancer, say US researchers who found that overall survival (OS) was comparable regardless of the timing of radiotherapy initiation.
“These results validate the findings of 2 prior randomized trials and possibly justify the delay of prostate [radiotherapy] for patients currently receiving ADT until COVID-19 infection rates in the community and hospitals are lower,” writes the team in a research letter to JAMA Oncology.
Vinayak Muralidhar (Harvard Medical School, Boston, Massachusetts) and co-investigators drew on the US National Cancer Database to identify 63,858 men who received external beam radiotherapy plus ADT for unfavorable intermediate-, high-, or very-high-risk prostate cancer between 2004 and 2014.
In the unfavorable intermediate-risk group, the 10-year OS rate was 59.2% for the men who started radiotherapy 0–60 days before initiating ADT and a comparable 57.9%, 62.3%, and 58.9% for those who began radiotherapy after ADT at 1–60 days, 61–120 days, and 121–180 days, respectively.
The findings were similar for the high- or very-high-risk group, with corresponding 10-year rates of 58.9%, 51.7%, 54.8%, and 52.4%.
And multivariable analysis adjusting for parameters such as age, ethnicity, comorbidity, Gleason score, T stage, and geographic location showed no significant difference in OS between patients who initiated radiotherapy before ADT and those who started it after ADT.
Muralidhar and colleagues additionally found no significant association between radiotherapy timing and OS when using a continuous, non-linear model.
They acknowledge the study limitations, including “the short follow-up period, retrospective design, lack of information about ADT duration, and possible data entry errors in the database.”
But the team nevertheless believes that “if COVID-19 outbreaks continue to occur sporadically during the coming months to years, these data could allow future flexibility about the timing of [radiotherapy] initiation.”
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