In a recent study published in the Archives of Physical Medicine and Rehabilitation, researchers examined the effect of exercise modalities on cancer-related fatigue (CRF).
CRF is a persistent, distressing, and subjective sense of emotional, physical, and cognitive exhaustion associated with cancer or its treatment. CRF is perceived as more severe, not fully relieved by rest, and often accompanied by insomnia, pain, depression, etc. Fatigue is a major adverse effect reported by cancer patients on chemotherapy.
CRF is a significant short- and long-term burden for cancer patients and survivors and an indicator of mortality. CRF is undertreated despite being one of the most frequent concerns after treatment. The American Society of Clinical Oncology (ASCO) guidelines recommend that health professionals implement psychological, exercise, and pharmacologic interventions for CRF management.
About the study
In the present systematic review and network meta-analysis, researchers compared the effectiveness of distinct exercise modalities in lowering CRF in cancer patients on chemotherapy. Participants aged 18 or older undergoing cancer treatment were included without restrictions on gender, cancer type/stage, and chemotherapy types.
Studies implementing exercise sessions before, during, or after chemotherapy and between treatment sessions were included. Randomized controlled trials (RCTs) were selected with no publication status/date or language restrictions. Several databases, including MEDLINE, Embase, Scopus, and Web of Science, among others, were searched for articles until January 15, 2022.
Articles were screened for relevance using title, abstract, and keywords data, and the full text of all articles was reviewed for compliance with inclusion criteria. Two researchers extracted characteristics and outcome data from studies. Exercise modalities were aerobic, resistance, flexibility, moderate-intensity continuous training (MICT), high-intensity interval training (HIIT), light martial arts, and yoga.
Statistical findings on the effect of exercise on CRF were extracted. Methodological quality was assessed using the PEDro scale. The revised Cochrane risk of bias (RoB-2) tool was used to determine the risk of bias in studies. The short-term effect of exercise modalities on CRF was examined with a frequentist network meta-analysis. Cochran’s Q statistic and the inconsistency index were used to assess heterogeneity and inconsistency among studies.
In total, 47 RCTs with 4,056 subjects were included. Their average age was 52.6, and most participants (82.1%) were females. Twenty-three studies included breast cancer patients, 11 had participants with different cancers, four included leukemia patients, and three studies had colon cancer patients, among others. Nearly 49% of studies included patients with cancer stages I – III.
Patients underwent adjuvant chemotherapy in 21 studies, neo-adjuvant in one, inductive in five, consolidation in one, palliative in one, and adjuvant/neo-adjuvant in seven studies. Eleven studies did not specify chemotherapy type. The duration of exercise interventions ranged between 3 and 27 weeks, and the follow-up ranged between three weeks and four years.
Four studies reported follow-up data, 30 presented only immediate post-intervention data, and 13 reported both. Twenty-seven studies had a good, while 20 had a fair methodological quality. A high risk of bias was estimated for 27 studies, while 20 had some risk of bias concerns. Forty-two studies involving 18 interventions and 58 comparisons were selected for network meta-analysis.
The researchers observed that usual care with aerobic and resistance exercise (low- or moderate-intensity) was more effective than usual care with flexibility training. There were no significant differences between standard care alone and usual care with exercise interventions. The strength of certainty was low/very low. No significant inconsistency was observed.
There was no significant effect on CRF between usual care alone and exercise interventions among breast, colon, or acute myeloid leukemia patients during follow-up. A few studies reported significant results with exercise interventions over standard care alone in breast cancer patients. One study noted that resistance training with HIIT was more effective on total/cognitive CRF at two years.
Another study demonstrated that HIIT with resistance training or MICT was effective on behavioral, total, and affective/emotional CRF 12 months post-intervention. Moderate- or high-intensity aerobic, flexibility, and resistance training effectively ameliorated cognitive, behavioral, and physical/sensory CRF at one-year follow-up in ovarian cancer patients.
The findings suggested a positive trend favoring aerobic and resistance exercise over usual care alone or usual care with flexibility exercise, albeit statistically insignificant. Notably, heterogeneity in implementing exercise interventions might have influenced the findings. The lack of standardization and heterogeneity in CRF assessment must be considered in future clinical studies.