MRI response to focal salvage HDR prostate brachytherapy for locally recurrent prostate cancer after external-beam radiotherapy.
Bibliographic record
Abstract
e631 Background: For local recurrence after external-beam radiotherapy, salvage therapy options include surgery, brachytherapy, cryotherapy or high-frequency ultrasound, though there is a significant risk of serious complications (e.g. fistula, incontinence, bladder neck contracture). In the meantime, MRI technology has evolved (e.g. DCE and DWI) such that the sensitivity of detecting viable cancer within the prostate is now more than 70%. Therefore, we initiated a pilot study of focal salvage HDR prostate brachytherapy in patients screened with a MRI with the hypothesis that focal treatment, rather than whole gland, would lead to less complications but similar local control. The MRI response is presented here. Methods: This study was approved by the institution’s research ethics board. Eligible patients included: biopsy-confirmed local recurrence > 30 months after completing XRT, MRI demonstrating solitary recurrence confined to the prostate, negative metastatic workup, IPSS < 15, post-XRT PSA < 10ng/mL, prostate volume ≤ 50cc. Salvage ultrasound-based HDR brachytherapy was performed with a prescription dose of 27Gy divided over two implants separated by 1 week to the target volume (TV) as seen on MRI with dose constraints to the urethra and rectum. All MRI scans were completed with 3T and included T2W, DCE and DWI. Lesions suspicious for cancer were scored using PI-RADS methodology pre-brachytherapy, and using a 5-point scale post-brachytherapy. Results: Fifteen patients were accrued. Thus far, 6 of 15 patients have completed a post-brachytherapy MRI (median 530 days; range 307-653). The baseline MRI characteristics of these 5 patients include: PI-RADS 4 (n = 1), 5 (n = 4), not specified (n = 1); median size 9 mm (range 7-9); T2 (n = 5) and T3a (n = 1); median prostate volume 28mL (20-63). In the post-brachytherapy MRI, the treated intraprostatic lesion no longer showed areas of cancer in 5 patients. Two patients developed a new focus of cancer in the prostate. Patients were not routinely biopsied after brachytherapy. Conclusions: Preliminary data from MRI suggests that there is a treatment response in most patients after focal salvage brachytherapy. Clinical trial information: NCT01583920.
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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 | 0.000 | 0.001 |
| 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) | 0.003 | 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 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".