Author(s): HERZOG, K., BAUER, N., SCHERER-TRAME, S., SIEMENS, W., WISKEMANN, J. , Institution: NATIONAL CENTER FOR TUMOR DISEASES (NCT) HEIDELBERG, Country: GERMANY, Abstract-ID: 576

INTRODUCTION:
Exercise interventions are consistently evidenced as effective supportive therapy measures in oncology. Meta-analyses and clinical guidelines demonstrate beneficial effects in quality of life, physical function, cardiorespiratory fitness, and improvements in treatment-related adverse effects through aerobic and resistance training. However, individual studies report substantial interindividual variability, including cases of “non-response.” To date, no systematic review has examined non-response to aerobic- and resistance-based exercise interventions in cancer patients. The aim of this review is to quantify the prevalence of non-response and identify associated factors.
METHODS:
A systematic literature search was conducted between May and October 2025 in PubMed, Embase, and Web of Science. The PICO-based search strategy included terms such as “cancer,” “exercise,” “non-responder,” “response heterogeneity,” “endurance,” and “resistance.” Screening and study selection were performed independently by two reviewers. Inclusion criteria were: (i) adult oncological populations, (ii) supervised endurance and/or resistance training interventions, (iii) explicit quantification of non-responders and/or extractable data showing no or negative changes in relevant health-related outcomes (e.g., VO₂peak, muscular strength, fatigue), and (iv) intervention studies, including randomized controlled trials (RCT), controlled trials, clinical trials, and feasibility studies.
RESULTS:
Of 1.447 studies identified after deduplication, 250 were selected for full-text screening. Of the five studies identified, two were RCTs with a non-exercising a control group; the remaining three were clinical trials without a control condition. Included studies were targeting both aerobic-related and strength-related outcomes. Potential moderators and contributing factors identified include baseline fitness, treatment history, training dose/volume, level of supervision, classification approaches, inflammatory and medication profiles, and adherence.
CONCLUSION:
This review demonstrates that non-response to aerobic and resistance exercise occurs in a subset of cancer patients, despite overall positive effects of exercise interventions. Evidence remains limited due to the small number of studies explicitly quantifying non-response and substantial heterogeneity in study design, outcome measures, and response definitions. Potential associated factors include baseline fitness, treatment-related characteristics, and training dose. Non-response to aerobic and resistance exercise in cancer patients is a relevant but insufficiently studied phenomenon. Future research should apply standardized response classifications, include control conditions, and identify moderators of training adaptations to support more individualized exercise prescriptions in oncology.