Delaying radiation therapy to a certain extent may make little difference in survival outcomes for prostate cancer patients.

Delaying radiation therapy has little effect on survival among prostate cancer patients

August 18, 2020
by John R. Fischer, Senior Reporter
Delaying radiation therapy due to the COVID-19 pandemic may make little difference in mortality outcomes for patients with prostate cancer.

Researchers at Brigham and Women’s Hospital found that conducting radiation therapy at a different time than originally planned was unlikely to affect survival for men with unfavorable intermediate-risk or high-risk localized prostate cancer, and allowed them to stay home and minimize their exposure to COVID-19, while continuing to receive hormone therapy.

"Our findings suggest that for men with localized (non-metastatic) unfavorable intermediate-risk and high-risk prostate cancer who choose to undergo hormone therapy (androgen deprivation therapy/ADT) and radiation, there may not be a negative impact on overall survival if patients receiving ADT delay the start of radiotherapy for several months," first author Edward Christopher Dee, a fourth-year student at Harvard Medical School, told HCB News. "The option to delay treatment may nuance the shared decisions that patients and providers make, especially when taking into consideration the potential risk of contracting COVID-19 while traveling to the hospital for daily radiation treatments."

Radiation therapy is often administered to patients with localized prostate cancer in conjunction with 6-to-36 months of androgen deprivation therapy (hormone therapy). It often starts after two months of hormone therapy, in accordance with findings made in preclinical trials. Two of these trials, however, found within a small window that starting radiation at this exact time did not affect outcomes.

The investigators tested these findings in a trial of their own, using a cohort of more than 63,000 cases of localized prostate cancer from the National Cancer Database that were diagnosed between 2004 and 2014. They recognized that this type of data set could reveal unmeasured differences between patients that were not accounted for but explained the findings.

The cases were separated into four groups based on when radiation started relative to hormone therapy. Among patients with unfavorable intermediate-risk PC, those who started radiation treatment in a period of 0 to 60 days before hormone therapy had a 10-year survival outcome of 59.2%, while those that started one to 60 days after had one of 57.9%. Patients who started 61 to 120 days after had a 62.3% rate; and those who began radiation treatment 121 to 180 days after had one of 58.9%. Deaths recorded for this group were 4220 in total.

Little difference in survival outcomes was also found among men with high-risk or very high-risk PC, with rates calculated to be 58.9%; 51.7%; 54.8%; and 52.4%, respectively. Total deaths were 10,959.

"If we consider the potential (and oftentimes very real) risks of COVID-19 for patients with cancer -- who are often at higher risk of worse COVID-19 outcomes -- these findings may allow deferral of radiation to a safer time when COVID-19 is less rampant," said Dee. "Of course, it is critical to involve patients in this decision-making process and weigh their own pros and cons, as well as to consider the patient's whole context, that is, their prostate cancer must be viewed in the context of their other comorbidities and risks such as ongoing COVID-19 transmission in the community."

He adds that he and his colleagues will also assess how delaying radiation impacts survival for other types of cancer, head and neck and gastrointestinal malignancies. "Interestingly, for some cancers, delays in treatment have been shown to negatively impact survival. Helping to characterize those -- and to further study which cancers are not negatively impacted by treatment delays -- may help guide decisions patients make regarding delaying treatment. It would be interesting to assess other outcomes as well, including quality of life, need for more extensive treatment after the delays, and others."

Funding was provided by the National Cancer Institute.

The findings were published in JAMA Oncology.