Standard Dose (Mayo Regimen) 5-Fluorouracil and Low Dose Folinic Acid: Prohibitive Toxicity?
Bibliographic record
Abstract
Despite the perception that standard 5-fluorouracil/folinic acid (5-FU/FA) (425 mg/m2 per day and 20 mg/m2 per day intravenously once daily x 5 every 4 or 5 weeks) is well tolerated, we have been impressed by toxicity seen and frequent need for dose modification. We performed a retrospective analysis to quantitate the proportion of patients experiencing toxicity and attempted to identify associated clinical characteristics. One hundred thirty-four patients received 5-FU/FA at standard doses described by the Mayo regimen. Patient characteristics were as follows: female 35%, median age 66 years, Eastern Cooperative Oncology Group performance status less than or equal to 2, 96%. Sixty-eight percent received chemotherapy for metastatic disease. Forty-seven patients (35%+/-8%) experienced significant toxicity and were unable to receive the second cycle as scheduled: 76% required dose reduction, 11% discontinued therapy (including two toxic deaths), 11% discontinued therapy during the first cycle, and 2% required dose delay. Logistic regression was used to explore the following as predictors of toxicity: age, sex, performance status, adjuvant versus metastatic setting, prior chemotherapy, prior radiation, mean corpuscular volume, red blood cell distribution width, albumin, alkaline phosphatase, aspartate aminotransferase, bilirubin, and calculated creatinine clearance. No clinical characteristic was found to predict toxicity. Only high bilirubin approached statistical significance. We conclude that standard 5-FU/FA, when used in the general population, is associated with significant toxicity. Known clinical characteristics are not helpful in predicting toxicity. The lack of previous formal phase I evaluation of this regimen of 5-FU/FA raises concerns regarding its safety and generalizability in clinical practice.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 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".