Background: Cancer recurrence is an important care challenge for breast cancer survivors. It is necessary to understand and identify the barriers and facilitators that affect the decision to start retreatment by those facing breast cancer recurrence compared to factors affecting their decision to start the initial treatment, which is different. Objectives: This study is part of a qualitative study with a grounded theory approach, which was conducted to explain the facilitating and inhibiting factors affecting the decision to start retreatment in survivors of breast cancer recurrence, using a qualitative content analysis method. Methods: This study was conducted based on the experiences of 16 patients with breast cancer recurrence and 2 oncologists to confirm the findings of the effective inhibiting and facilitating factors in patients’ decisions to start retreatment for breast cancer recurrence in one of the hospitals in Tehran, Iran. The samples were selected, using the purposeful sampling method trying to have maximum diversity. Data were collected through in-depth semi-structured telephone interviews from November 2020 to November 2021 and analyzed, using the conventional content analysis method following the Elo and Kyngas method, which includes 3 phases, including the preparation phase, the organizing phase, and the reporting phase. Credibility, transferability, dependability, confirmability, and authenticity were used for determining the trustworthiness of data. Results: Both groups of inhibiting and facilitating factors were divided into 5 categories, including individual factors, social factors, family factors, illness characteristics, and treatment-related factors. Also, each category included sub-categories in two groups of inhibiting and facilitating factors affecting the decision to start treatment again. Conclusions: Based on the results of the present study, it is necessary to increase the awareness of patients with breast cancer by the treatment staff about the possibility of recurrence and to know the factors influencing their decision-making process to start retreatment. Nurses should play the role of advisors, educators, and supporters of the patients in this field.