Exercise as it relates to Disease/The effect of resistance training on breast cancer patients

This Wikibooks page critiques "Randomized, controlled trial of resistance training in breast cancer patients receiving adjuvant radiotherapy: results on cancer-related fatigue and quality of life" by Steindorf et al. (2014)

What is the background to this research?
Breast cancer is the most prevalent cancer in females, with an estimated 2.3 million diagnoses in 2020. Of these, many require ongoing treatment such as adjuvant radiotherapy. The disease itself and these treatments are often associated with a range of side effects, most commonly fatigue, that are detrimental to the patient's quality of life (QoL).

This paper explores the effect of resistance training on the fatigue and QoL of breast cancer patients undergoing adjuvant radiotherapy.

Minimal research has been conducted within this field so this paper fills an essential gap in existing knowledge. There has only been one small study on breast cancer patients undergoing radiotherapy. Previous research has only investigated the effects of aerobic training or a combination of aerobic and resistance training. Psychological rather than physiological effects have been studied.

It is vital to discover the most effective methods in reducing fatigue and improving the QoL of such a significant percentage of the worldwide population.

Where is the research from?
This research was conducted at the Institute of Sports and Sport Science of the University of Heidelberg in Germany. It is one of the leading research institutions in Europe with a university ranking of 42 for 2022. Each of the authors have numerous other papers published within the cancer field. For example, Professor Steindorf has 204 publications and has conducted prior research at the German Cancer Research Centre and the National Centre for Tumour Diseases, investigating physical activity, fatigue, QoL and different cancers.

This research appears in an Elsevier medical journal, Annals of Oncology, which is considered to be one of the leading journals with a high impact factor of 32.976.

It has also been presented at multiple conferences in Germany and the United States of America.

This research was funded by the Interdisciplinary Research Funding Program of the National Centre for Tumour Diseases and partially supported by the cancer foundations ‘Stiftung Leben mit Krebs’ and ‘Manfred-Lautenschlaeger-Stiftung’. It does not appear that there would be any personal gain by these findings.

The authors have declared no conflicts of interest.

What kind of research was this?
This study was a prospective randomised control trial (RCT). 80 breast cancer patients were assigned to the resistance training intervention and 80 were assigned to the control group muscle relaxation program. Both groups were designed to have potential psychosocial benefits, so if exercise had an effect it was in addition to this. These allocations were conducted by someone not involved in the study who used predetermined lists (not accessible by study personnel) with a random block size, arranged by age and baseline fatigue level. There was no blinding in this study as the patients and the researchers knew which treatment was being received.

RCTs are desirable as they allow the researcher to make causal inferences. Since the participants were randomly allocated, selection bias and confounding factors were minimised and the groups were comparable. Because it is a prospective study, recall error is eliminated. This means the findings are more likely to be valid and generalisable, and the researcher is able to successfully determine the effect of resistance training.

Many other studies within this field used a similar framework since alternative designs are unable to produce the same level of evidence for a causal relationship.

What did the research involve?
The participants in both the experimental and control group had 2 60-minute professionally administered sessions each week for 12 weeks, beginning on the day of the first radiotherapy session. The experimental group participated in resistance training using 8 machines. They completed 3 sets of 8-12 repetitions at 60-80% of 1 repetition maximum. The control group participated in muscle relaxation with no aerobic or strength components.

These outcomes were measured pre-radiotherapy (baseline), post-radiotherapy (week 7) and post-intervention (week 13):


 * fatigue- self-assessment Fatigue Assessment questionnaire
 * QoL- self-assessment QoL questionnaire and breast cancer specific questionnaire
 * depressive symptoms- self-assessment depression scale for cancer patients
 * cognitive function- trail-making test assessing visual attention and task switching
 * muscle strength- isometric and isokinetic tests for upper and lower extremity
 * endurance performance- VO2peak measured on a bicycle ergometer

The baseline scores were compared to the post-intervention scores to see if resistance training had an effect on any variables measured.

Limitations
The main limitation is that most outcomes were measured using self-assessments, which introduces bias and threatens the validity and reliability. However, the nature of this study makes this unavoidable because it is difficult to measure these outcomes without using self-assessment questionnaires. The methodology was designed in a way that maximises validity and reliability, making it a suitable approach.

What were the basic results?

 * Fatigue- significant reduction in total (P=0.044) and physical fatigue (P=0.013) for resistance training when compared to control, but not for affective (P=0.91) or cognitive (P=0.65)
 * QoL- no significant difference in global QoL (P=0.37) but resistance training improves QoL aspects: role function (P=0.035), pain (P=0.040), future perspective (P=0.047)


 * Muscle strength- significant improvements with resistance training (P<0.0001)
 * Endurance performance- no significant difference between groups

What conclusions can we take from this research?
This study found that resistance training reduces fatigue and improves some aspects of QoL, beyond the psychosocial aspects, for breast cancer patients receiving adjuvant radiotherapy. Additionally, but unsurprisingly, it also improves muscle strength which counters a side effect of treatment. Steindorf et al. inferred that for optimal patient outcomes, resistance training should be implemented alongside treatment.

These findings align with previous studies. Resistance exercise has been found to reduce treatment side effects in prostate cancer patients. Many studies have investigated the benefits of aerobic training for breast cancer patients. This study confirmed that resistance training alone does not provide those cardiorespiratory benefits. Therefore, it can be deduced that the optimal program should incorporate both resistance and aerobic training.

Practical advice
Every person has different needs and risk factors to consider, particularly within this population group, so it is vital to follow the specific recommendations given by health professionals. Whilst executing the resistance and aerobic program the patient should be supervised by a professional and have their critical measures (blood pressure, heart rate and oxygen saturation) monitored throughout the session. They should progress to 150 minutes of moderate intensity activity and 2 sessions of resistance training per week. Activities could include running on the treadmill and whole body machine-based exercises.

Further information/resources
Breast cancer:

https://www.who.int/news-room/fact-sheets/detail/breast-cancer

Exercise guidelines for cancer patients:

https://www.cancer.org/treatment/survivorship-during-and-after-treatment/staying-active/physical-activity-and-the-cancer-patient.html

Resistance training:

https://www.betterhealth.vic.gov.au/health/healthyliving/resistance-training-health-benefits