A92 DOSE ESCALATION STUDY OF CYBERKNIFE® BOOST IN UNRESECTABLE LOCALLY ADVANCED PANCREATIC CANCER
Bibliographic record
Abstract
Abstract Background Pancreatic cancer is the 4th deadliest cancer in Canada, with an overall 5-year survival of only 6%. Every year, approximately 4000 Canadians are diagnosed with pancreatic cancer, and only 10–15% of these patients have surgically resectable disease. No satisfactory treatment exists for patients with inoperable locally advanced pancreatic carcinoma. The best survival has been achieved using a combination of chemotherapy and radiotherapy. Conventional radiotherapy has inadequate local disease control as the therapeutic radiation dose to the tumour is limited by the sensitivities of surrounding tissues. Stereotactic body radiotherapy (SBRT) is a minimally invasive treatment technique that allows for ultra-high doses of radiation to be delivered to small areas. The CyberKnife® Robotic Radiosurgery System is a radiation unit designed to deliver SBRT. Fiducial markers placed by endoscopic ultrasound help direct the radiotherapy. It is hypothesized that a higher overall dose of radiation will result in higher rates of local control, and potentially improved survival. Aims The goal of this study is to establish the safety and feasibility of using stereotactic body radiotherapy boost technique via CyberKnife in treating unresectable locally advanced pancreatic cancer, as well as to determine the maximal tolerable radiation dose (MTD) of the SBRT boost that can be safely delivered. Methods This is a prospective single-arm, single-institution phase I Time-to-event Continual Reassessment Methodology (TITE-CRM) radiation dose escalation trial. This study enrolled patients aged 18–84 with pathologically confirmed pancreatic cancer who were determined to have surgically unresectable disease, with an ECOG ≤2. These patients were treated with SBRT prior to starting conventional radiotherapy, which consisted of a total dose of 45 Gy in 25 fractions over 5 weeks. Results Between 2012 and 2018, a total of 11 patients met the eligibility criteria of this study. Their ages ranged from 61 to 84 with a mean of 71.5 years, and they were 64% (7/11) male. At the time of this analysis, 10 of the 11 patients had passed away. The mean and median survival times were 413 days and 313 days, respectively. Three of the patients had significant complications attributed to the radiotherapy, 2 gastric outlet obstructions and 1 deep duodenal ulcer. The doses used ranged from 21 Gy in 3 fractions to 50 Gy in 5 fractions. Conclusions This phase 1, single arm study demonstrates that stereotactic body radiotherapy in the treatment of locally advanced, unresectable pancreatic cancer is technically feasible. When combined with conventional radiotherapy, this therapy is generally well tolerated, and can effectively deliver higher doses of radiation to pancreatic malignancies. Doses up to 50 Gy in 5 fractions were tolerated, with the most common dose being 21 Gy in 3 fractions. Funding Agencies National Pancreatic Cancer Canada Foundation
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 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".