Materials and Methods: This randomized controlled trial was conducted on 76 mastectomized patients who referred to the Breast Cancer Supportive Association and Shahid Ghazi Tabatabaei hospital in Tabriz-Iran during 2017-2018. Participants were randomly allocated to counseling and control groups. Totally, six 60-90-minute counseling sessions were held for the counseling group regarding health promotion and health-promoting lifestyle including self-efficacy. General self-efficacy questionnaire was completed by the patients pre-intervention and 4 weeks post-intervention through interviews. Independent t test and analysis of covariance (ANCOVA) test were used to analyze the data.

Results: No significant difference was observed between the study groups in terms of demographic variables and the pre-intervention score of self-efficacy (P > 0.05). The results of ANCOVA test by adjusting the pre-intervention score indicated that the mean score of the perceived self-efficacy was significantly more in the counseling group compared to the control group at four weeks post-intervention (adjusted mean difference =7.1; 95 % CI = 5.5 to 10.5; P < 0.001).

Conclusions: In general, group counseling can enhance the perceived self-efficacy in mastectomized women. Therefore, considering the role of self-efficacy in promoting the health of breast cancer patients, counseling sessions should be held for mastectomized women to improve their self-efficacy.