Physical activity and exercise behaviour of breast cancer survivors: nationwide cross-sectional survey.

Objectives: High physical activity levels have been associated with longer, healthier lifespans and improved quality of life among breast cancer survivors. The Japanese clinical guidelines for breast cancer survivors, similar to those in the USA, strongly recommend maintaining high physical activity levels. However, the extent of adherence to these guidelines among breast cancer survivors in Japan is unclear. This study aimed to assess adherence to guideline-recommended physical activities and identify associated factors.

Methods: Self-administered questionnaires were distributed to breast cancer survivors without recurrence or metastasis from 34 facilities across Japan, with approximately 30 survivors per facility, between March 2019 and August 2020. The questionnaire collected information on participants' backgrounds, physical activity levels (assessed using the Global Physical Activity Questionnaire) and potential factors influencing their physical activity. Logistic regression analysis was performed to identify the factors associated with meeting the guideline recommendations.

Results: In total, 791 patients (77.5%) were investigated, with 50.5% meeting the physical activity recommendations outlined in the guidelines. Factors associated with meeting the guideline recommendations included higher self-efficacy (OR 1.58, 95% CI 1.29 to 1.94), greater perceived social support (OR 1.54, 95% CI 1.26 to 1.89), lower annual household income (OR 1.58, 95% CI 1.07 to 2.33), relief from cancer-related symptoms through physical activity (OR 1.81, 95% CI 1.13 to 2.94) and urban location (OR 1.50, 95% CI 1.03 to 2.20).

Conclusions: Half of the breast cancer survivors in Japan did not meet the recommended physical activity levels, and several factors influencing adherence were identified.