A retrospective analysis of tumor size (TS) as a continuous rather than discrete variable in advanced pancreatic cancer
Bibliographic record
Abstract
e15565 Background: Objective “response rate” (RR) dichotomizes patients into categories of “response” (complete or partial) and “non-response”. This ignores a lot of data captured within the trial on tumor size changes, and may miss clinically important effects on tumor growth may occur in the absence of a response. Analyzing TS as a continuous variable (TS-CV) has been suggested as a more robust indicator of efficacy. Methods: Tumor size data from 2 randomized controlled trials in advanced pancreatic cancer conducted by NCIC.CTG were analyzed; NCIC.PA1 randomized patients to BAY12–9566 (MMPI) or Gemcitabine (Gem) and demonstrated a large and significant survival (OS) benefit for Gem (6.7 vs 3.4 months), NCIC.PA.3 randomized patients to Gem ± Erlotinib and showed a modest OS benefit for the combination (HR =0.81). In PA1, an early interim analysis (IA) using absence of progression as the primary measure did not halt accrual. Measures of TS at baseline and 8 wks were transformed and represented as a logarithm of the sum of the longest diameters. The difference in logarithms (d-LTS) from baseline to 8 weeks was calculated to indicate change in tumor size. Groups were compared using Wilcoxon rank-sum test. Results: In PA1, TS was significantly decreased in the Gem arm (mean d-LTS 0.087 on MMPI vs. -0.066 on Gem; p<0.0001), in keeping with the OS benefit (p<0.001). The decrease was also significant in the interim analysis cohort (p=0.007) and this result would, if used, have halted accrual earlier. In PA3, for all patients, decrease in TS was significantly larger for the combination arm (mean d- LTS -0.148 on combination vs. -0.114 on Gem; p=0.04), consistent with the OS benefit (p=0.038). Analysis on the 1st 130 patients yielded similar results (p=0.02) Conclusions: Tumor size changes may be a reasonable endpoint for screening efficacy trials in advanced pancreatic cancer. These results support further assessment of this alternate efficacy endpoint. No significant financial relationships to disclose.
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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 | 0.006 | 0.007 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".