Effects of exercise on motivational outcomes in rectal cancer patients during and after neoadjuvant chemoradiation: a phase II randomized controlled trial

Standard treatment for locally advanced rectal cancer is neoadjuvant chemoradiation therapy (NACRT) followed by total mesorectal excision, which involves removal of the rectal tumor and surrounding tissue.1 NACRT improves local disease control and pathologic complete response,1 however, the treatment also causes acute adverse effects that can lead to a decline in functional status and quality of life.2 Exercise during cancer treatment improves some patient-reported outcomes, objective physical functioning, and treatment outcomes for some patient groups,3, 4, 5 however, a limited amount of research has focused on rectal cancer patients receiving NACRT. We previously reported a phase II randomized controlled trial examining the effects of exercise during and after NACRT for rectal cancer.6

The Exercise During and After Neoadjuvant Rectal Cancer Treatment (EXERT) trial randomized 36 patients to supervised high-intensity interval training (HIIT) during NACRT followed by unsupervised moderate-to-vigorous intensity exercise (MVE) after NACRT, or usual care. In the primary paper, we reported no significant effects of the exercise intervention on our primary outcome of cardiorespiratory fitness; however, we did report the first evidence for improvement in treatment efficacy.6 The number of patients achieving a pathologic complete/near complete response was significantly higher in the exercise group (56%) compared with the usual care group (18%). In a secondary paper focused on patient-reported outcomes, we identified negative effects of the exercise program on several symptoms and components of quality of life during NACRT that mostly dissipated after NACRT.7 In the present paper, we report the effects of the exercise program on exercise motivation during and after NACRT. Identifying and understanding motivation for exercise during and after NACRT is important in helping rectal cancer patients sustain the exercise behavior and achieve potential clinical benefit.

Our assessment of the motivational outcomes was guided by the Theory of Planned Behavior (TPB)8 which was developed to predict and explain human behavior. The immediate precursor of a behavior is the intention to perform the behavior, which reflects how hard a person is willing to try. In turn, intention is influenced by a combination of (1) attitude towards the behavior (i.e., positive or negative evaluation of the behavior) based on instrumental (perceived benefits and harms) and affective (perceived enjoyment and displeasure) attitudes, (2) subjective norms (i.e., perceived social pressure to perform the behavior) based on injunctive (perceived support from others) and descriptive (perceived engagement of others in the behavior) norms, and (3) perceived behavioral control (i.e., perceived difficulty of performing the behavior) based on self-efficacy (confidence in performing the behavior and overcoming barriers) and perceived controllability (perceived control over the behavior).

The primary purpose of this study was to examine the effects of the supervised HIIT program during NACRT and the unsupervised MVE program after NACRT on exercise motivation outcomes. We also aimed to identify self-reported benefits, harms, and barriers to exercise both during and after NACRT. Based on previous research in cancer patients 9, 10, 11, 12 and our own preliminary data from a phase I study in this patient group,13 we hypothesized that the exercise interventions during and after NACRT would be perceived as more enjoyable and less difficult than anticipated. We also hypothesized that the exercise group would report a more positive motivation for future exercise after the exercise program. Finally, based on our phase II trial results showing some negative effects of exercise on symptoms and quality of life,7 we hypothesized that patients would perceive some harms of the exercise program, especially related to side effects during NACRT.

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