Nurses in the control group accepted the other non-fertility (standard) nursing training for the intervention, whereas those in the experimental group accepted the oncofertility training. Based on research ethics and design, a standard education course was held for the control group after completing data collection in the nursing experimental group. We began to recruit patients into the patient experimental group after all nurses completed their educational courses.

We designed the education program according to Klein's NDM model, which explored the reasoning mechanism behind decision-making (Klein, 1993). It depends on the on-the-job training date in each unit. The education program consisted of the following: (1) Information accumulation: explanations of common cancer therapies related to subsequent infertility, psychological and mental change in cancer survivors with infertility, the necessity and method of early determination of fertility intention, and type of fertility preservation. (2) Sense-making: situational case sharing, emphasis on the guidance interaction between experienced and novice nurses to understand the patient's situation. (3) Decision-making: how to provide support, how to correspond, and attitudes toward people with strong fertility intention.

The decisional conflict was measured using the Chinese version of the decisional conflict scale. Each item was rated on a five-point Likert scale, ranging from zero to 4. The score was calculated by averaging the sum of individual item scores, then multiplying the product by 25. Hence, the scores range from 0 to 100. A higher score indicates higher decisional conflict. Both nursing and patient participants were asked to fill out the questionnaire.

An Oncofertility Barrier Scale was developed to assess nurses' perceptions of comprehensive barriers regarding oncofertility care. The responses to each item were provided using a five-point Likert scale. A higher scale score meant the nurses perceived that it was more difficult to provide oncofertility care.

We used the Infertility Knowledge Questionnaire to measure both of nurses' and patients' knowledge of infertility in patients with breast cancer. Total scores for the 11 items ranged from zero to 11. Centimeters were used to show the ratio of correct answers visually. A higher score meant a greater level of knowledge about infertility. Both nursing and patient participants were asked to fill out the questionnaire.

The Fertility Intention Scale with 15 items was used to measure patients' fertility intentions. The standardized scale ranged from 1 to 5 points on a five-point Likert scale. Higher scores indicated a greater degree of fertility intention.