The effectiveness of physical exercise for people with cancer
We have summarised the results from five systematic reviews, on the effects of exercise for cancer patients during and after cancer treatment, including a total of 119 randomised clinical trials.
- Year: June 2016
- By: Norwegian Institute of Public Health
The National Cancer Strategy for 2013-2017 published by the Norwegian Ministry of Health and Care Services, notes that physical activity is an important adjunctive treatment both during active cancer treatment and after the treatment is completed. We have summarised the results from five systematic reviews, on the effects of exercise for cancer patients during and after cancer treatment, including a total of 119 randomised clinical trials.
In summary, the reviews show:
• It is uncertain if exercise during active cancer treatment has an effect on quality of life, self reported physical function, anxiety, depression and fatigue.
• Exercise for cancer survivors might have a positive effect on quality of life, self reported physical function, anxiety and fatigue.
• Weight training does not seem to increase the severity of lymphedema in women who have received breast cancer surgery.
The results from this review should be interpreted with caution. The certainty of the evidence, based on the included systematic reviews, is low or very low mainly due to small studies with high risk of bias.
There is a need for research investigating if any specific type, intensity or duration of physical exercise gives better results than others.
The evidence is sparse for the effect of exercise during and after cancer treatment for the outcomes survival, recurrence of cancer and serious adverse events.
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The National Cancer Strategy for 2013-2017 published by The Norwegian Ministry of Health and Care Services, notes that physical activity is an important adjunctive treatment both during and after completion of active cancer treatment. Physical activity also has a preventative effect on several forms of cancer.
Approximately 31 651 Norwegians were diagnosed with cancer in 2014 compared to 14 000 in 1980. The increase in cancer prevalence is mainly due to an increase in life expectancy, that cancer is more prevalent in the elderly and that certain forms of cancer have become more common. More patients are also now cured of cancer and an increasing number are living longer with cancer. At the end of 2014 there were 242 398 people in Norway who had survived or who were living with cancer.
In February 2015, The Norwegian Knowledge Centre for the Health Services, (now the Knowledge Centre for the Health Services in the Norwegian Institute of Public Health) was asked by the Norwegian Cancer Society and the organisation Active against cancer (Aktiv mot kreft) to search for and critically appraise systematic reviews on the effectiveness of physical activity and exercise for adults who are undergoing active treatment or who are cancer survivors. The aim of the review was to answer the following questions:
1. What is the effect of physical activity and exercise for adults undergoing active treatment for cancer?
2. What is the effect of physical activity and exercise for adult cancer survivors?
We conducted an overview of systematic reviews. We searched for systematic reviews in the following databases: MEDLINE, Embase, PsycINFO, Amed, CINAHL, Web of Science, PEDro, PubMed, Epistemonikos, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment Database (HTA) up to April 2015.
Titles and abstracts were screened independently by two researchers according to pre-defined selection criteria. The systematic reviews were critically appraised using a checklist published by the Norwegian Knowledge Centre for the Health Services in the Norwegian Institute of Public Health and the results were summarised in both text form and tables. We assessed the certainty of the evidence, or our confidence in the results, using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) tool and described the certainty of the evidence as: high (⊕⊕⊕⊕), moderate (⊕⊕⊕⊝), low (⊕⊕⊝⊝) or very low (⊕⊝⊝⊝).
We often use standard ways of expressing the certainty of the documentation. When the evidence is of low certainty we use may and when the certainty is moderate we use the term probably about the effect estimate. If the evidence is of low certainty we say that we are uncertain of the effect estimate.
Two Cochrane reviews from 2012 were included; one assessed the effect of physical exercise on patients undergoing active treatment and one the effect of physical exercise on cancer survivors. Additionally, one Cochrane review assessing the effect of aerobic physical exercise for adult patients with haematological malignancies, one review assessing the effect of weight training for women with breast cancer who were at risk of developing cancer related lymphedema and one Cochrane review assessing the effect of exercise for cancer cachexia (weight loss) in adults were included.
During active treatment
One Cochrane review, which included 56 randomised clinical trials (4826 participants), evaluated the effectiveness of exercise on cancer patients undergoing active treatment. Cancer diagnoses in trial participants included breast, gynaecological, haematological, lung and prostate cancer. The majority of the included patients had breast cancer and received chemotherapy or radiation therapy, or a combination of the two therapies. Most studies included walking as the sole intervention or in combination with cycling or weight training. It varied when in the course of the treatment the exercise was given. The exercise interventions lasted approximately 12 weeks in most of the studies, and the outcomes were measured post-treatment. The results indicated that exercise may have a positive on quality of life (SMD 0.47, 95 % KI 0.16 to 0.79) (⊕⊝⊝⊝), fatigue (SMD -0.73, 95 % CI -1.14 to -0.31) (⊕⊝⊝⊝) and self-reported physical function (SMD 0.69, 95% CI 0.16 to 1.22) (⊕⊝⊝⊝) for patients undergoing active cancer treatment but as the certainty of the evidence was very low, the results are very uncertain.
After treatment – cancer survivors
One Cochrane review, which included 40 randomised clinical trials (3694 participants) evaluated the effect of exercise on cancer survivors. The cancer diagnoses of the study participants included breast, colorectal, cervical, lymphoma, lung, prostate, and other cancers. The most common form was breast cancer. The mode of exercise intervention was a combination of activities such as weight exercise, different forms of endurance training and stretching. Some studies investigated the effect of walking, cycling, yoga or Qigong. The exercise interventions lasted approximately 12 weeks in most of the studies and the outcomes were measured post-treatment. Exercise probably results in a reduction of fatigue symptoms (SMD -0.8, 95 % CI -1.50 to -0.14) (⊕⊕⊕⊝), possibly improves quality of life (SMD 0.48, 95 % CI 0.16 to 0.81) (⊕⊕⊝⊝), possibly improves self-reported physical function (SMD 0.29, 95 % CI -0.08 to 0.66) (⊕⊕⊝⊝) and may lead to less symptoms of anxiety (SMD -0.26, 95 % CI -0.44 to -0.07) (⊕⊕⊝⊝). It is uncertain if exercise reduces depression symptoms or pain, or if it improves sleep.
One Cochrane review, which included nine randomised clinical trials with 818 participants, evaluated the effectiveness of aerobic physical exercise during and after active treatment among patients with haematological malignancies. The participants suffered from different haematological malignancies (leukaemia, lymphoma and myeloma) and most of the patients received hematopoietic stem cell transplantation. The exercise was given as adjunctive treatment and the exercise intervention consisted of various walking intervention programmes of different durations and levels of intensity. Exercise probably reduces fatigue (SMD 0.24, 95 % CI 0.08 to 0.40) (⊕⊕⊕⊝) and improves self-reported physical function (SMD 0.33, 95 % CI 0.13 to 0.52) (⊕⊕⊕⊝), possibly improves Quality of Life (SMD 0.26, 95 % CI 0.03 to 0.49) (⊕⊕⊝⊝) and reduces symptoms of depression (SMD 0.25, 95 % CI 0.0 to 0.5) (⊕⊕⊝⊝). It is uncertain if exercise has an effect on the 100 day survival rate (RR 0.93, 95 % CI 0.59 to 1.47) (⊕⊕⊕⊝) or if there is an increase in serious adverse effects such as serious bleeding, infection, deep venous thrombosis or pneumonia (RR 1.44; 95% CI 0.96 to 2.18) (⊕⊕⊝⊝).
One systematic review of eight trials and 1091 participants evaluated the effect of a weight training intervention for women who were at risk for developing lymphedema and who had been operated for breast cancer. Some of the patients also received hormone treatment, chemotherapy, or radiation therapy. Six trials included patients at risk of breast cancer-related lymphedema and two trials included patients diagnosed with lymphedema. The majority of the exercise interventions were supervised by a physiotherapist or a certified exercise professional and lasted two to 18 months. The weight exercise training started four weeks to five years after the operation. Patients in one group exercised during chemotherapy. The weight training program was categorised as low intensity in six trials and as moderate intensity in two trials. It is uncertain if exercise changed the prevalence of lymphedema (RR 0.77, 95 % CI 0.52 to 1.15) (⊕⊕⊝⊝). While there may be no difference in the severity of lymphedema in the two groups (SMD -0.09, 95 % CI -0.23 to 0.05) (⊕⊕⊝⊝), weight training probably increases muscle strength (SMD 0.93, 95 % CI 0.73 to 1.12) (⊕⊕⊕⊝).
One Cochrane review which evaluated exercise for patients with involuntary weight loss did not find any trials and is not described further here.
The included reviews did not give detailed information for the included patients, such as age, co-morbidity (such as cardio vascular disease), disease severity (curative versus palliative), types of cancer treatment provided and when the participants had received active cancer treatment (months or years before the exercise interventions). The reviews also provided scarce information on the characteristics of the exercise interventions.
We included five systematic reviews of high methodological quality. The reviews reported findings from 119 randomised clinical trials with a total of approximately 10 000 participants. Currently it is uncertain if physical exercise as an adjunctive treatment improves treatment outcomes, influences recurrence of cancer or improves survival for patients with cancer. The certainty of the evidence was low or very low for the majority of the comparisons and outcomes. This means that for many outcomes we cannot be certain about the effects of the interventions and new research may change the conclusions presented here. The certainty of the evidence was influenced by the information available on the methodological quality of the trials that the reviews identified. Many of the trials were unclear in the way they reported their methods, such as how the randomisation procedures were conducted, whether adjustments were made for baseline differences and whether outcome assessors were blinded.
This report is an overview of systematic reviews. Such an umbrella review is a good opportunity to obtain a broad picture of a research field, but it is important to note that the methods used may not give a complete picture. For example, primary studies on the effects of physical activity and exercise for adults who are undergoing active treatment for cancer or who are cancer survivors, may have been published after the search date of the included systematic reviews. This may be especially true for new treatment technologies, for example for breast cancer or colon cancer. Current techniques are more precise (e.g. micro surgery) than previously used techniques.
Scarce information regarding the patients and the interventions in the systematic reviews makes it difficult to evaluate the true effect of physical exercise as an adjunctive treatment. Variation occurs in cancer treatment and prognoses. The prognosis for a man in his forties with an aggressive colon cancer, for example, may be worse than a man in his sixties who has mild prostate cancer. Such factors were not taken into account in the meta-analyses included in this overview.
The included studies were small, and the methods used often poorly described. Evidence was lacking for several of the outcomes, such as survival, the recurrence of cancer and for serious adverse events.
Internationally and nationally guidelines are updated to include research on the benefit of physical activity and exercise for patients undergoing cancer treatment and for cancer survivors. To provide evidence based healthcare, the best research evidence needs to be integrated with clinical expertise and patient values in the given setting. Patients undergoing cancer treatment should be offered guidance and advice by their doctor in accordance with evidence-based clinical guidelines.
We lack of evidence on the effects of physical exercise during and after cancer treatment for several outcomes, such as survival, the recurrence of cancer and serious adverse events.
It is uncertain if exercise improves outcomes in cancer patients undergoing active treatment. Exercise may however have a positive effect on quality of life, physical function, anxiety and fatigue for cancer survivors. Weight training for women who have received breast cancer surgery does not seem to influence the severity of lymphedema.
We do not know whether any particular type, intensity or duration of physical exercise will give better effect on the outcomes.