Background: Breast cancer and chemotherapy can cause substantial psychological distress, including cognitive preoccupation and future anxiety/fear of recurrence. This study evaluated the association of online mindfulness-based counseling with these outcomes among women with breast cancer receiving chemotherapy, using the eight-item Breast Cancer Psychological Care Questionnaire (BC-PPCS-8).

Methods: In this two-arm, parallel-group randomized controlled trial conducted in Kerman, Iran, 70 women with stage I–III breast cancer receiving chemotherapy were randomly assigned to an eight-week online mindfulness-based counseling program or usual care. Cancer-related psychological distress was assessed using the eight-item Breast Cancer Psychological Care Questionnaire (BC-PPCS-8) at baseline, post-intervention, and one-month follow-up. Baseline characteristics were compared using t-tests, chi-square tests, or Fisher’s exact tests, as appropriate, and post-intervention outcomes were compared using the Mann–Whitney Utest.

Results: Of 84 patients assessed for eligibility, 70 were randomized in equal numbers to mindfulness-based counseling or usual care. Post-intervention outcome data were obtained from 34 participants in the counseling group and 35 in the control group. Groups were comparable at baseline regarding demographic and clinical characteristics, including age, marital status, education, income, cancer type, time since diagnosis, and chemotherapy sessions (all p>0.05). At post-intervention, participants receiving mindfulness-based counseling reported significantly lower cognitive preoccupation (4.00±0.00 vs. 11.31±3.07), future anxiety/fear of recurrence (4.00±0.00 vs. 13.49±2.08), and total BC-PPCS-8 scores (8.00±0.00 vs. 24.80±4.58) than control participants (all p<0.001).

Conclusion: Online mindfulness-based counseling was associated with lower post-intervention cognitive preoccupation, future anxiety/fear of recurrence, and psychological distress than usual care among women receiving chemotherapy for breast cancer. This accessible intervention may complement psychosocial care; larger longitudinal trials should confirm the magnitude and durability of effects.