A Phase I/II Trial of Fairly Brief Androgen Suppression and Stereotactic Radiation Therapy for High-Risk Prostate Cancer (FASTR-2): Preliminary Results and Toxicity Analysis
Bibliographic record
Abstract
PURPOSE: FASTR was designed to provide a compact treatment course for high-risk prostate cancer patients but was discontinued because of excess toxicity. We present the results of FASTR-2, which used a lower dose to the prostate (35 Gy vs 40 Gy), smaller posterior PTV margin (4 mm vs 5 mm) and omitted nodal radiation to lower the volumes of rectum receiving high and intermediate doses compared with FASTR. Gastrointestinal (GI) and genitourinary (GU) toxicities at baseline, 6 weeks, 6 months, and 1 year and biochemical control rates are presented. METHODS AND MATERIALS: Eligibility included high-risk prostate cancer (cT3/4, prostate-specific antigen >20 or Gleason Score ≥8), age ≥70 or refused standard treatment, and no evidence of metastatic disease. Patients received 18 months of androgen deprivation therapy starting 2 months before radiation. Clinical target volume was defined as prostate plus proximal 1-cm seminal vesicles. PTV was a nonuniform expansion around clinical target volume (4 mm posteriorly, 5 mm in all other directions). Volumetric arc therapy was used for treatment delivery (35 Gy delivered in 5 weekly fractions of 7 Gy each), and cone beam computed tomography with soft tissue matching (no fiducial placement) was used for daily image guidance. Toxicity was assessed at 6 weeks, 6 months, and 1 year according to Common Toxicity Criteria. RESULTS: In the study, 30 patients were enrolled in FASTR-2 between 2015 and 2017. Two patients were withdrawn owing to ineligibility after enrollment. One patient (3.7%) reported grade 2 GI toxicity at 6 weeks. There was no reported grade ≥2 GI toxicity at 6 months or 1 year. There were no reported episodes of rectal bleeding. Four patients (14.8%), 5 patients (17.9%), and 5 patients (21.7%) reported grade 2 GU toxicity at 6 weeks, 6 months, and 1 year, respectively. There were no reported cases of grade ≥3 GU toxicity. The most common toxicities were nocturia and urinary frequency or urgency. CONCLUSIONS: FASTR-2 was more tolerable than FASTR, with no grade ≥3 toxicities reported, in keeping with expectations based on our previous FASTR analysis. Long-term follow-up is necessary to ensure disease control and toxicity outcomes are comparable to conventional high-risk treatment paradigms.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".