AS offers men with indolent, organ-confined disease the option to defer curative treatment (e.g., surgery, radiation) and its associated adverse effects (e.g., sexual dysfunction, urinary incontinence) that pose a significant threat to quality of life. However, disease progression, and potentially the psychosocial burden of living with untreated cancer, can ultimately lead to AS discontinuation.
Epidemiologic studies suggest that high levels of physical activity (PA) are associated with reduced PCa progression2 and mortality.3 In men with low-risk disease, promising evidence demonstrates that lifestyle changes, including PA, may inhibit tumor progression4 while improving psychological health.5 However, limited evidence exists on the relationship between PA levels and AS discontinuation that may be related to tumour progression or anxiety.
To examine the association between PA and AS duration, we conducted a retrospective cohort study in a sample of 421 men with low-risk PCa, 107 of whom underwent curative treatment. The duration of AS ranged from 7-116 months. In our cox regression analysis, we found that PA status post-diagnosis did not significantly influence time to AS discontinuation. Covariates in our models that were associated with a significantly greater risk of curative treatment initiation were prostate-specific antigen values most proximal to AS initiation (HR, 1.11; 95% CI 1.03 to 1.21)and the number of positive cores from the diagnostic biopsy (HR, 1.34; 95% CI 1.12 to 1.61). While our dataset did not include specific reasons for why AS was discontinued, we found that the majority of men who initiated curative treatment demonstrated disease progression (increased histopathological grade, number of positive biopsy cores, and percent involved of the worst core).
While novel, our study results should be considered with some caution. The robustness of our statistical model could be improved with the inclusion of other possible determinants of AS discontinuation (e.g., body mass index, marital status). Furthermore, the PA data in our study are self-reported and subject to social desirability bias, whereas objective PA measurement via accelerometry is likely to be a more accurate representation of this health behaviour. Finally, given that anxiety and fear of disease progression can also influence the decision to initiate curative treatment,6 our data are limited because of the absence of explicit details on why patients discontinued AS in the absence of disease progression. Whether PA can protect against disease-related psychological morbidity during AS remains an important area of exploration.
Written by: Efthymios Papadopoulos1,2, Shabbir M.H. Alibhai2,3 and Daniel Santa Mina1,2,3
1. Ph.D. Candidate, M.Sc., R.Kin, Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
2. Department of Supportive Care, Princess Margaret Cancer Centre, Toronto, ON, Canada
3. Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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3. Wang Y, Jacobs EJ, Gapstur SM, Maliniak ML, Gansler T, McCullough ML et al. Recreational Physical Activity in Relation to Prostate Cancer–specific Mortality Among Men with Nonmetastatic Prostate Cancer. Eur Urol2017; 72: 931–939.
4. Ornish D, Weidner G, Fair WR, Marlin R, Pettengill EB, Raisin CJ et al. Intensive lifestyle changes may affect the progression of prostate cancer. J Urol2005; 174: 1065–9; discussion 1069-70.
5. Bourke L, Stevenson R, Turner R, Hooper R, Sasieni P, Greasley R et al. Exercise training as a novel primary treatment for localised prostate cancer: A multi-site randomised controlled phase II study. Sci Rep2018. doi:10.1038/s41598-018-26682-0.
6. Klotz L. Active surveillance, quality of life, and cancer-related anxiety. Eur. Urol. 2013; 64: 37–39.
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