Fibromyalgia in cancer patients: a systematic review and clinical implications for integrated care

In oncology, fibromyalgia (FM) is increasingly recognized as a clinically relevant comorbidity, as cancer patients frequently present overlapping symptoms such as pain, fatigue, and sleep disturbances, complicating clinical assessment and management. Moreover, anticancer treatments may trigger or exacerbate FM-like symptoms. This systematic review aimed to synthesize the available evidence on FM in oncological patients, focusing on prevalence, clinical characteristics, and its impact on pain perception, Health-Related Quality of Life (HRQoL), and treatment adherence.

A comprehensive literature search was conducted in PubMed, Embase, and Scopus, including studies published from 2014 to 2024. Eligible studies, in accordance with PRISMA guidelines, included observational, cross-sectional and interventional designs involving adult patients with FM in the context of cancer or cancer-related pain. Conversely, studies not assessing FM in relation to cancer or cancer-related pain were excluded. Risk of bias was evaluated using ROBINS-I tool and the RoB 2 tool.

A total of 11 studies were included, encompassing heterogeneous populations and study designs, thereby precluding a quantitative synthesis of the literature. Overall, evidence suggests that FM did not increase cancer risk but significantly contributes to pain amplification, higher symptom burden, reduced HRQoL, and impaired treatment adherence. Pre-existing nociplastic pain features were associated with premature discontinuation of oncological therapies, particularly endocrine treatments. The substantial overlap between FM-related and cancer-related symptoms may represent a major diagnostic challenge in clinical practice.

This review highlights a substantial research gap, as evidence in oncology populations remains limited and is affected by moderate to high risk of bias, partly due to confounding factors. Nevertheless, FM appears to be a relevant comorbidity in oncology, warranting further investigation. High-quality longitudinal studies are needed to clarify causal associations and support evidence-based management.

The protocol for this systematic review was retrospectively registered on the Open Science Framework (OSF; https://doi.org/10.17605/OSF.IO/X5N29).