{"doi":"10.62347/qccz2316","title":"Tumor bearing in untreated breast cancer decreases exercise tolerance without lowering maximal oxygen uptake in rats","abstract":"Breast cancer patients' maximal O 2 uptake (V 2 max) values average 60-80% of age-predicted values which is often attributed to adjuvant therapy rather than risk factors, comorbidities, or the tumor and associated factors (e.g., pro-inflammatory cytokines).It is crucial to understand the physiological mechanisms behind exercise intolerance in breast cancer patients to enhance targeted interventions; however, the effect of breast cancer, as an isolated condition on V 2 max, exercise tolerance, and resting cardiac function has not been investigated.We hypothesized that breast cancer, in the absence of underlying conditions or chemotherapy, would lower V 2 max, exercise tolerance, and cardiac function in proportion to tumor mass.Female Fischer-344 rats (~6-8 months, n = 8) were acclimatized to treadmill running for 5 days at 25 m/min for 5 min/day.To measure V 2 max, rats were placed within a plexiglass metabolic chamber connected to CO 2 and O 2 analyzers.Tests began at 25 m/min and increased (5 m/min) until exhaustion.Cardiac function was determined by echocardiography before rats received a mammary intraductal injection of rat adenocarcinoma cells (MATBIII, 6 10 3 in 50 l saline).Tumor growth was monitored daily and ~7 days following palpation (~24 days post-injection), V 2 max and echocardiography measurements were repeated.Tumor mass and volume were 2.1 0.6 g and 1685 428 (range 256-3749) mm 3 , respectively.Body mass (217 6 vs 218 6 g), V 2 max (72.1 2.7 vs 70.0 2.8 ml/kgmin; P > 0.05), and all measures of cardiac function were unchanged following tumor formation, with no significant correlation between tumor mass and V 2 max (P > 0.05).However, time to exhaustion (376 20 vs 297 25 s), final treadmill speed (48 1 vs 42 2 m/s), distance run (209 16 vs 152 18 m), and total work (45 3 vs 32 4 mkg) were significantly reduced with tumor bearing.Contrary to our hypothesis, breast cancer did not affect V 2 max or cardiac function, but reduced exercise tolerance.","journal":"American Journal of Cancer Research","year":2025,"id":562543,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9625,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":451513,"name":"Ramona E. Weber","orcid":"0000-0001-5110-270X","position":0,"is_corresponding":true}],"reference_count":80,"raw_metadata":null,"created_at":"2026-07-19T02:56:05.550545Z","pmid":"40084375","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}