In 2020, the World Health Organization updated the 2010 Global Recommendations on Physical Activity for Health . They reaffirmed the fact that PA is required for optimal health outcomes, and provided new recommendations for reducing sedentary behavior, especially in patients with chronic diseases such as cancer .
PA has been demonstrated to improve quality of life and mitigate complications of cancer treatment. Knowledge of the factors that influence PA may allow physicians to identify the patients expected to have less PA and intervene early. Our findings are consistent with a previous study by Ottenbacher et al., which demonstrated that disruption of activities due to urinary difficulties reduced PA among recently diagnosed prostate cancer patients in the United States and Canada . It is important to manage urinary difficulties because they adversely affect PA. A study in Korean prostate cancer survivors reported that patients with incontinence had a greater interest in Kegel and pelvic floor exercises . Early identification of urinary difficulties is crucial for early interventions, such as educating and motivating patients for Kegel and pelvic floor exercises.
Bøhn et al. demonstrated that bowel symptoms had a statistically significant association with PA levels in patients treated with a radiotherapy and ADT, but not in patients treated with radical prostatectomy or ADT alone . However, our study did not demonstrate a statistically significant association between bowel symptoms and PA levels. Ottenbacher et al. also did not observe an association between bowel symptoms and PA levels . We did not categorize the patients on the basis of their treatments because of the small number of patients treated with radiotherapy. Further studies are needed that include patients treated with radiotherapy.
In contrast to previous studies that reported old age as a barrier to PA among prostate cancer survivors , we did not observe a statistically significant association between PA and age using univariate logistic regression (Table 2). Bøhn et al. demonstrated a significant association between PA and age in prostate cancer patients treated with radical prostatectomy, but not in those treated with ADT or radiotherapy and ADT . In our study, the patients had ability to perform a 2-minute walking test and those who wanted to participate in exercise were included. Therefore, the age could not be related to PA.
In Asian populations, prostate cancer has a different epidemiology compared to Western populations . Therefore, the factors affecting PA after prostate cancer treatment may also be different. However, only a few studies have been conducted in East Asian populations, including Koreans. One study investigated the PA levels and barriers and preferences regarding PA in 111 Korean prostate cancer survivors. That study demonstrated that the greatest barriers to exercise in prostate cancer survivors were poor health, lack of time, and lack of facilities. However, the questionnaire used in that study did not evaluate complications of prostate cancer, such as urination or defecation difficulties. Therefore, the effects of these complications were not studied .
The main strength of this study was that we studied all the factors that lead to sarcopenia [8–10]. Cancer is associated with severe muscle wasting due to decreased calories and protein intake, reduced endocrine signaling, and increased pro-inflammatory activity . Sarcopenia is common in prostate cancer patients, especially those treated with hormonal therapy. In a previous study, sarcopenia was determined to be independently associated with cancer-specific survival among patients with metastatic, hormone-sensitive prostate cancer . Various studies have reported that PA decreases the risk of sarcopenia in older patients [12, 13, 28]. However, few studies have investigated the association between PA and sarcopenia in prostate cancer patients, especially in Asian populations.
In our study, RSMI, maximal grip strength, and physical performance (gait speed and five times sit to stand test) did not influence PA; however, given the small cases of components of sarcopenia, it could be stastically insignificant due to lower statistical power.
There were a few limitations to our study. All of the study participants were enrolled from a single hospital. Therefore, our results may not be generalizable to the entire population. The sample size was small and could not be categorized based on the treatments (surgical, hormonal, or radiation therapy). A previous study investigated multiple aspects of PA, including those related to occupation, sports, household, transport, leisure-time, and sedentary activities. Urinary incontinence after radical prostatectomy significantly affected the household PA levels . Conversely, our study only evaluated one aspect of PA. Lastly, comorbidities that affect patient health, such as hypertension and diabetes mellitus, were not evaluated. Patients with severe cardiopulmonary diseases were excluded from the study. A previous study found no significant association between PA and comorbidities in prostate cancer patients . So, comorbidities which might introduce bias would not affect result in our study