How does stereotactic body radiotherapy compare to standard external beam radiotherapy or low-dose rate brachytherapy for low-risk prostate cancer?
Bibliographic record
Abstract
e16070 Background: Stereotactic body radiotherapy (SBRT) is an emerging radiotherapy technique that appears to be efficacious, well tolerated and convenient. However, outcomes for patients treated with SBRT are unknown compared to more conventional radiation options for patients with prostate cancer. The purpose of this study is to evaluate and compare late toxicities and biochemical disease-free survival (bDFS) of low risk prostate cancer patients treated SBRT (35Gy/5 fractions), standard external beam radiotherapy (STND; median 76Gy/38 fractions) or low-dose brachytherapy (LDR; iodine-125, 145Gy) at the Odette Cancer Centre. Methods: Consecutive patients with low risk prostate cancer treated with radiation from 2006-2008 were analyzed. Patients treated with SBRT were part of a phase 2 prospective clinical trial; patients treated with STND or LDR had data abstracted from medical charts retrospectively. Patients treated with neoadjuvant androgen deprivation therapy were excluded from biochemical analyses. Univariate (UVA) and multivariate analyses (MVA) of Cox proportional hazard model were conducted to identify significant covariates predicting bDFS. Results: A total of 357 low-risk prostate cancer patients were identified (84 SBRT, 81 STND and 192 LDR). The median follow-up was 57, 62, and 59 months, respectively. At baseline, 85% of patients were T1c, 15% T2a; 100% had GS 6; median PSA 5.9 ng/ml. There were more patients in the STND and LDR cohort who had T2a disease (6%, 21% and 16%, p= 0.013) and the mean PSA was higher in the STND cohort (6.08, 6.69, and 6.02, p=0.017). Patients who received LDR experienced more late hematuria (0%, 1.23% and 11.98%, p<0.0001); otherwise there were no significant differences in late toxicities observed. There were no significant differences in bDFS (97.4% vs 96.9% vs 97.2% at 60 months, p=0.94). There were no covariates identified predicting bDFS on UVA or MVA, including treatment type. Conclusions: SBRT, STND and LDR show equivalent effectiveness and both external beam techniques showed less hematuria than LDR. However, SBRT and LDR are more convenient and less costly than STND. Further prospective studies of SBRT are ongoing.
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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 | 0.018 | 0.047 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.003 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 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".