Published in Oncology · February 17, 2021ASCO GU 2021: No Benefit From Radiation Dose Intensification i

[podsart]

February 11, 2021—Dose-intensified salvage radiotherapy was no more effective than conventional radiotherapy for the treatment of recurrent prostate cancer after radical prostatectomy, according to a phase III study presented at the American Society of Clinical Oncology Genitourinary Cancers Symposium 2021, which took place virtually from February 11 to 13.

“In patients who experience biochemical progression after radical prostatectomy, salvage radiation therapy to the prostate bed is the only available curative treatment option,” said study lead author and presenter Pirus Ghadjar, MD, of Charité Universitätsmedizin Berlin in Germany, during his presentation of the data. “Retrospective comparisons have suggested that biochemical progression-free survival (PFS) is improved around 2.5% per gray dose intensification, but results of well-conducted randomized trials are lacking until now.”

SAKK 09/10 was a randomized, open-label, multicenter phase III trial performed in 24 centers located across Switzerland, Germany, and Belgium. Overall, 350 patients with prostate cancer were recruited for the study, 344 of whom were aged between 48 and 75 years. Patients were eligible for the study if they had undergone radical prostatectomy 12 weeks previously. They were randomized 1:1 to receive 64 Gy of conventional radiotherapy in 32 daily fractions of 2 Gy (n = 175) or 70 Gy of dose-intensified radiotherapy in 35 daily fractions of 2 Gy (n = 175). Median PSA at the time of randomization was 0.3 ng/mL (range 0.03–1.61 ng/mL).

The primary endpoint of the study was freedom from biochemical progression, defined as prostate-specific antigen (PSA) ³ 0.4 ng/mL. Secondary endpoints were clinical PFS, time to hormonal treatment, overall survival (OS), acute and late toxicity determined by National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) version 4.0, and quality of life determined by the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ)-C30 and EORTC QLQ-PR25.

At the time of data cut-off, the median follow-up period was 6.2 years (interquartile range 5.5–7.2 years), and a total of 138 biochemical progression events had occurred. At this time, the estimated freedom from biochemical progression was 62.3% for the conventional dose arm and 61.3% for the dose-intensified arm. Median duration of freedom from biochemical progression was 8.2 years in the conventional arm and 7.6 years in the dose-intensified arm. The hazard ratio for freedom from biochemical progression, after adjustment by stratification factors, was 1.14 (95% confidence interval 0.82–1.60, P = .04).

There were no significant differences in clinical PFS, OS, or time to hormonal treatment between the treatment arms. Late grade 2 gastrointestinal toxicity was observed in 12 patients receiving conventional dose radiotherapy (7.3%) and 35 patients who received dose-intensified radiotherapy (20%). Rates of late grade 2 genitourinary toxicity were 21% and 26%, respectively. Late grade 3 gastrointestinal toxicity occurred in 7 patients in the conventional dose arm (4.2%) and in 4 patients in the dose-intensified arm (2.3%). For late grade 3 genitourinary toxicity, the rates were 8% and 4%, respectively.

Quality of life data revealed no significant differences between the study arms, either with respect to changes in urinary symptoms or bowel symptoms from baseline.

“Dose-intensified salvage radiation therapy was not superior to conventional dose,” concluded said Dr. Ghadjar. “Higher dose was associated with increased late rectal toxicity.”

[Tall_Allen]

Here's the link:

ascopost.com/news/february-...

While it's true that everyone does not need the extra dose, this very similar Japanese randomized clinical trial found that patients with higher grade PC benefited from dose intensification:

redjournal.org/article/S036...

Importantly, both trials found that there was no significant increase in toxicity, even with the extra dose. This was even true for the Swiss study, on which many patients were treated using 3D-CRT ( a less accurate kind of dose delivery than IGRT/IMRT used in the Japanese study).

So my conclusion is, since there is no excess toxicity from the higher dose, and it may be beneficial for some patients, why not use it? In fact, if genomics suggest a more virulent, radioresistant kind of PC, even higher doses may be used.

[podsart in reply to Tall_Allen]

Thanks.

[podsart]

Thanks