CHICAGO – The long-term side effects of postoperative prostate bed radiation therapy (HYPORT) for prostate cancer are similar to those of conventional radiotherapy, a new study concludes.
Lead author Mark K.
He noted that NRG-GU003 is the first study to compare a short course of radiotherapy at higher doses with a well-established, standard 7-week course of radiotherapy for patients who have undergone radical prostatectomy.
The results showed no significant or clinical differences between the two treatments on the EPIC composite with respect to gastrointestinal (GI) or genitourinary (GU) toxicity at 2 years (s = .12).
Although the patients who received HYPORT initially experienced more severe symptoms, Boyonowski commented, “these symptoms disappeared at 6 months and were similar to the other group – and remained that way until the end of the study.” He is professor of radiation oncology and director of genitourinary cancers in the division of radiation oncology at Stanford University School of Medicine in Stanford, California.
It is concluded that “HYPORT is a new acceptable standard of practice for patients receiving radiotherapy after prostatectomy”.
He said there are advantages with this approach for all parties. For patients, it takes a shorter time commitment, and there are fewer expenses related to travel and co-pay. For healthcare practitioners, productivity is improved and costs reduced.
The new study was presented here at the plenary meeting of the American Society of Radiation Oncology (ASTRO) 2021 annual meeting.
Change practice or not?
“These findings are likely to change,” commented Sophia Kamran, MD, a radiation oncologist at Massachusetts General Hospital Cancer Center and professor of radiation oncology at Harvard Medical School, Boston, MA. She was speaking during an ASTRO press conference highlighting the new findings.
“The field is moving toward unfractionated radiotherapy for prostate cancer, and it has been widely accepted in an intact setting,” she commented. She has now suggested that it should also be accepted in the post-prostatectomy setting.
“Using contemporary radiation techniques and image guidance, we are able to target volume and can safely deliver under-fractionated radiotherapy that allows for multiple benefits on multiple fronts for our patients and clinicians as well,” she said.
However, the invited speaker at the plenary said that more data was needed.
said Brendan Mahal, MD. He is an assistant professor of radiation oncology at the University of Miami Miller School of Medicine-Sylvester Comprehensive Cancer Center, Miami, Florida.
Evidence in places where lymph nodes and ADT . are treated [androgen-deprivation therapy] It is also used there is a need.”
However, Mahal noted that data from the NRG-GU003 trial could help reduce barriers to radiotherapy after prostatectomy. “It can improve access to potentially curative treatment and reduce financial and time toxicity, and it can also increase adherence to completing radiotherapy,” he said.
For his own clinical practice, Mahal made it clear that he would consider using HYPORT in a select group of appropriate patients in cases where lymph nodes are not being treated and in patients for whom long-course radiotherapy may create a barrier to potential curative treatment.
He added, “Patients should be counseled about the increased risk of GI symptoms at the end of radiotherapy and the potential risk of radiation cystitis,” as well as about the relatively unknown long-term/late GI side effects. Follow-up is limited, and long-term cancer control is unknown.”
Reported results are results after 24 months of radiotherapy.
No inferiority to the traditional approach
NRG-GU003 was a non-inferiority trial conducted on 296 men who had undergone prostatectomy. Patients were randomly assigned to receive either HYPORT (n = 144) or conventional therapy (n = 152).
With HYPORT, 62.5 Gy was administered to the prostate bed in 25 portions of 2.5 Gy. Patients who underwent conventional radiotherapy received 66.6 Gy in 37 fractions of 1.8 Gy.
Radiation therapy to the lymph nodes was not allowed; ADT was allowed for 6 months.
The combined primary endpoints were change in scores (24-month score minus baseline score) from the GU and GI domains of the EPIC questionnaire.
The authors found that compliance with EPIC was 100% at baseline, 83% at the end of treatment, 77% at 6 months, 78% at 12 months, and 73% at 24 months. Bujonowski noted that at the end of radiotherapy, mean changes in GU scores in both groups were neither clinically significant nor statistically significantly different and that the scores remained that way at 6 and 12 months after treatment.
However, there was a difference in the conclusion of radiotherapy. The mean change in GI scores was clinically and statistically significantly different (HYPORT mean GI score = 15.0; conventional treatment mean GI score = 6.8; q = .01).
These differences resolved at 6 and 12 months, and the 24-month mean changes in GU and GI scores for both groups were not statistically or clinically significant (HYPORT mean GU score = -5.2; mean conventional GU score = -3.0; s = .81; HYPORT means GI score = -2.2; Conventional mean GI = -1.5; s = .12).
After two years of treatment, there were no differences between the two groups with regard to biochemical or local failure.
The study was funded by the National Cancer Institute. Buyonowski has ties to Elsevier and Varian. Mahle did not disclose any related financial relationships
American Society of Radiation Oncology (ASTRO) 2021 Annual Meeting: Abstract 3. Filed October 25, 2021.
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