Dose escalation of five-fraction SABR for prostate cancer: Biochemical outcome and toxicity comparison of two prospective trials.
Bibliographic record
Abstract
224 Background: To compare the biochemical outcomes and toxicities of two different 5 fraction stereotactic ablative body radiotherapy (SABR) schedules for the treatment of localized prostate cancer. Methods: Two sequential phase I/II studies of 5-fraction SABR for the treatment of low and intermediate risk (LR and IR) prostate cancer have been conducted. In the first trial, 84 LR patients(pts) received 35 Gy in 5 fractions, once per week over 29 days (Group 1). In the second trial, 30 pts (18 LR, 11 IR) received 40 Gy in 5 fractions, once per week over 29 days (Group 2). Treatment was delivered to the prostate with intensity modulated radiotherapy using daily image guidance and a 4mm (Group 1) or 5 mm (Group 2) CTV-PTV margin. PSA nadir and bRFS(nadir+2 definition) were compared between the two groups. Acute (CTCv3.0), late (RTOG) and cumulative toxicity for late grade ≥ 2 GU/GI toxicities were also compared. Results: Median follow up was 74 (IQR 67-81) and 36 (IQR 32-39) months. Median PSA nadir was 0.4 ng/ml and 0.3 ng/ml. Time to PSA nadir was 54 and 32.5 months. 44.0% in group 1 and 30% in Group 2 experienced benign PSA bounce. There were 3 and 0 PSA failures in Groups 1 and 2. 2-, 4- and 6-year bRFS was 100%, 98.7% and 95.9% and 100%, 100% and not reached in groups 1 and 2, respectively (p=0.91). The only acute grade 3 toxicity was noticed in Group 1 (1 pt, GU). Late grade 4 GI toxicity was noted in Group 1 (1 pt, GI, fistula). Up to 4 years of follow-up, Group 2 pts have had a greater percentage of grade 2+ cumulative GU (5.0% vs 24.2%) and GI (7.6% vs 26.2%) toxicities. Conclusions: Pts receiving a dose escalated SABR had slightly lower PSA nadir and similar bRFS - longer follow up is needed to better estimate biochemical outcomes in Group 2. There seemed to be a greater risk of grade 2 toxicities in the higher dose cohort but grade 3+ toxicities were not increased. Quality of life analyses will be presented separately. Clinical trial information: NCT01578902 , NCT01146340 .[Table: see text]
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.009 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.005 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".