Introduction: Breast cancer is one of the most common types of cancer. The present research has been carried out to investigate the effectiveness of mindfulness-based cognitive therapy (MBCT) on quality of life and mood in women with breast cancer undergoing mastectomy.
 
Materials and Methods: In this clinical trial (code: IRCT2017040933315N1), 50 voluntary patients who had undergone mastectomy, were screened among the patients admitted to Omid  Hospital and Reza Treatment Center in Mashhad and were randomly divided into experimental group (n=25) and control group (n=25). First, both groups were evaluated in pretest phase. Then, the experimental group received group MBCT treatments during eight sessions of 120 minutes, but the control group received no treatment. At the end of treatment, both groups evaluated in post-test phase. Data collection tools included standard questionnaires temperament (POMS) and the quality of life questionnaire (SF-36). The data were analyzed based on covariance analysis using SPSS software (Version 20).
 
Results: Comparison of the mean scores of quality of life and mood showed a significant difference between the control and experimental groups after receiving the treatment (P<0.01).
 
Conclusion: Group mindfulness-based cognitive therapy can be considered as an effective and efficient approach to the quality of life and mood (anxiety and depression)   in women with breast cancer who have undergone mastectomy.