Skeletal Muscle Blood Flow, Oxygen Extraction and Consumption in Women Receiving Chemotherapy for Breast Cancer
Bibliographic record
Abstract
PURPOSE: Cardiac muscle injury is a well-recognized side effect of anthracycline chemotherapy and trastuzumab therapy for breast cancer. Preclinical studies have identified parallels in cell damage response and dysfunction between cardiac and skeletal muscle. However, assessment of the effect of treatment on skeletal muscle in patients has been limited to muscle strength. METHODS: Early stage breast cancer patients receiving chemotherapy including anthracyclines or trastuzumab enrolled into a RCT of a multi-disciplinary team intervention versus usual care. Patients underwent a MRI scan before the first and after the third chemotherapy treatment. A maximal incremental single leg plantar flexion test was performed followed by 15 min of rest. A 4-min steady state test was then performed at 60% of peak power. Beginning at end-exercise, time-resolved blood flow (popliteal vein, phase contrast MRI) and venous oxygen saturation (SvO2, susceptometry-based oximetry using deoxyhemoglobin as an intrinsic contrast agent) were measured with custom methods. These values were used to calculate lower leg VO2 using the Fick equation with [hemoglobin] (hb) extracted from clinical records and SaO2 measured via pulse oximetry. RESULTS: Twelve patients have completed both scans. Preliminary analyses were of change over time with both groups combined. Peak power did not change (15.7 ± 3.0 to 16.6 ± 3.8 W, p=0.227). After treatment, oxygen carrying capacity of the blood (hb*1.34*SaO2) was significantly decreased (median change = -17%, p=0.004) due to reduced hemoglobin (13.5 ± 13 to 11.2 ± 13 g/dL). Exercise blood flow increased (438 ± 119 to 633 ± 167 mL/min, median change=44%; p<0.001) out of proportion to this reduction. SaO2 and SvO2 did not change appreciably (~98% and 60%, respectively). As a result there was a small but non-significant increase in leg VO2 (30 ± 9 to 35 ± 13 mL/min, median change = 16%, p=0.165). Exercise mean arterial pressure decreased and heart rate increased after treatment (p=0.007, p=0.017). CONCLUSIONS: Our preliminary findings indicate that chemotherapy for breast cancer does not reduce oxygen extraction with isolated muscle exercise. Local blood flow increases partly in response to reduced oxygen-carrying capacity of the blood, but mechanisms for the remaining hyperemia response are unknown.
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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) | 0.000 | 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) | 0.002 | 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".