Effect of post-diagnosis exercise on depression symptoms, physical functioning and mortality in breast cancer survivors: A systematic review and meta-analysis of randomized control trials

Abstract

Background

Cancer is the second leading cause of death worldwide. Breast cancer, the most common cancer found in women, affects 2.1 million women annually and has the highest number of cancer related deaths. The objective of the current meta-analysis is to evaluate the effects of post-diagnosis exercises on depression, physical functioning, and mortality in breast cancer survivors.

Methods

The search for eligible articles was conducted through CINAHL, Medline/PubMed, Scopus, Cochrane, Emerald Insight and Web of Science, Embase database, MEDLINE In-Process, Elsevier, Google Scholar, PsycInfo, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), Allied and Complementary Medicine (AMED), Biosis Previews, SPORTDiscus, PEDro scientific databases from 1974 to 2020. Following the exclusion procedure, 26 articles yielded for final analysis. The combined statistics for depression, physical functioning, and mortality in breast cancer survivors were calculated using standardized mean differences (SMD). Standard errors and 95% confidence intervals (CI) were converted to standard deviations as required. For mortality, combined statistics were calculated using hazard ratios (HR). The 95% CIs were converted to standard errors as required. The forest plots display point estimates and 95% CIs.

Results

Statistically significant improvements on levels of depression were identified following the exercise intervention, suggesting that post-diagnosis physical activity leads to a decrease in depression scores. Overall, post-diagnosis exercise led to a 37% reduction in the rate of breast cancer-specific mortality. The all-cause mortality rate was decreased by 39% with the inclusion of moderate physical activity as the part of daily routine.

Conclusions

Future studies should look at how to improve the quality of life while incorporating physical activity as a daily routine after breast-cancer treatment.

Highlights

• • Women diagnosed with breast cancer experience the long-term physical and psychosocial effects of cancer and its treatment.
• • Sadness, depression, sleep, appetite changes, decreased quality of life are considered as the side effects of treatment.
• • Physical activity is statistically significant in reducing the risk of all-cause mortality, breast cancer-specific mortality.
• • There were statistically significant improvements in depression levels in patients who were physically active post-diagnosis.
• • Future studies are expected to investigate the long-term effects of exercise on the health of breast cancer survivors.

• 1

  Introduction

  Cancer is the second leading cause of death worldwide. In 2018, it was estimated to cause 9.6 million deaths, with breast cancer the most common among women, affecting 2.1 million women annually and causing the highest number of cancer deaths [1] . Although the incidence of breast cancer is higher among women in more developed regions, the incidence rates grow in almost all regions of the world, reaching 627,000 deaths in 2018 [1] .

  Breast cancer is the most common cancer in North American women (after skin cancers), with more than 3.5 million women with a history of breast cancer, including those currently being treated and women who have finished treatment [12] . The incidence of breast cancer in the United States began to decline in 2000 after rising in the previous two decades. From 2002–2003 alone, they fell by 7% [12] . Among the many theories put forward, one was that this decline was in part due to a decline in women’s use of hormone replacement therapy (HRT) after the results of a study called the Women’s Health Initiative were published in 2002 [12] . At present, the average lifetime risk of breast cancer in a woman in the United States is about 13%, with incidence rates increasing 0.3% per year. Furthermore, breast cancer risk varies by age and race/ethnicity [2] .

  During 2012–2016, the median age at the time of breast cancer diagnosis was 62 [1] . Black women under 45 years of age are more likely to have breast cancer than white women. Overall, Black women are more likely to die of breast cancer [12] . For Asian, Hispanic, and Native-American women, the risk of developing and dying from breast cancer is lower. Ashkenazi Jewish women have a higher risk of breast cancer because of a higher rate of BRCA mutations [12] . According to studies conducted in the period from 2013 to 2017, breast cancer incidence and death rates are highest among non-Hispanic (NH) whites (130.8 per 100,000), followed closely by NH blacks (126.7) [2] . However, NH black women have the highest breast cancer death rate (28.4 deaths per 100,000), more than double that in Asian/Pacific Islander (API) women (11.5), who have the lowest incidence and death rates [2] .

  Women diagnosed with breast cancer at stages I to III receive treatment, most often with a sequence of operations, postoperative chemotherapy, radiation therapy, and oral anti-estrogen drugs 345 . After treatment, many of these women experience the long-term physical and psychosocial effects of cancer and its treatment, including pain, fatigue, lymphedema, psychological disorders, anxiety, and depression 345 . Feelings of sadness, hopelessness characterize depression, sleep, appetite changes, in addition to delayed psychomotor development, decreased quality of life (QOL), impairment of social and professional functioning, and periodic bouts of suffering 345 . The depressive mood is commonly reported by breast cancer survivors, with a prevalence of 1.5–46%. Several factors contribute to the development of depression in cancer survivors [4] . Some have a poor psychological adjustment to specific symptoms (e.g., sexual, intestinal, fatigue), the severity of the symptoms (e.g., pain, fatigue), the treatment itself. Thus, chemotherapy causes hair loss, nausea, weight gain and affects fertility and sexuality, which can be perceived as unpleasant. In others, the treatment causes hypothyroidism, electrolyte imbalances, or anemia, increasing the risk of a depressive episode 345 . Therefore, managing general health and surviving at the stage of cancer is as important as the treatment. As a result, traditional approaches in monitoring cancer recurrence have expanded, including such factors as women’s health overall recovery management, i.e., psychosocial and physical effects, promoting a healthy lifestyle. This process is expected to involve health professionals from multiple fields of expertize (e.g., psychologists, physical therapists, nutritionists) [34] .

  The main aim of rehabilitation is to help patients return to their daily lives 678910 . A healthy lifestyle also reduces comorbidities, the risk of recurrence, and cancer deaths. Jung et al., in their analysis of 2042 breast cancer survivors (after menopause), reported that women who were not physically active before being diagnosed with breast cancer but increased their physical activity after diagnosis to recommended levels showed significant 50% reduction in overall mortality [6] . Furthermore, a 46% reduction in breast cancer mortality and a 42% improvement in relapse-free survivorship was reported compared to women who remained inactive [6] . This positive effect of physical activity was also confirmed in a meta-analysis of 717 breast cancer survivors who participated in 14 randomized controlled trials [7] . Physical activity resulted in statistically significant improvements in QOL [7] . Still, these findings are contradictory since they report that a healthy lifestyle affects women’s self-confidence, physical health, psychological state, body composition, and the likelihood of successful completion of chemotherapy, without causing lymphedema or significant adverse events 8910 . Moreover, these findings do not indicate whether a healthy lifestyle affects QOL of women after breast cancer treatment 8910 .