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Abstract                
Background & aim: one of the most common and disruptive symptoms experienced by cancer survivors is cancer related fatigue. This symptom can continue many years after cancer diagnosis, leading to reduced performance, quality of life, and significant socioeconomic outcomes. Therefore, the aim of this study was to evaluate the improvement of cancer-related fatigue in patients with breast and colorectal cancer who participated in the MBSR training program.
 
Methods: In the present clinical trial study, the statistical society included all patients with breast and colorectal cancer referred to Shahid Motahari Clinic and Amir Oncology Hospital (Shiraz, 2017-2018). 38 participants were selected through available sampling and randomly assigned to either experimental(n=19) or control(n=19) groups. The groups responded to the cancer related fatigue scale in pre-test and post-test. The results were analyzed using multivariate covariance (MANCOVA) analysis.
 
Results: the results of data analysis indicated that mindfulness-based stress reduction significantly decreased the mean scores of the fatigue subscales: Physical (F=141.49, p<0.0001), cognitive (F=66/23, p<0/0001), emotional (F= 58.44, P<0.0001), and overall fatigue score (F=5.66, P= 0.023) in the experimental group. That is, there was a significant difference between the two experimental and control groups in the mean of all dimensions of cancer related fatigue scale.
 
Conclusion: This study provided evidence that MBSR was effective in treating cancer-related fatigue in patients with colorectal and breast cancer. Therefor MBSR could be used as an effective intervention in medical centers and hospitals.