The goal of this observational study is to clarify the fertility status of young breast cancer patients, verify the independent impact of fertility behavior on the prognosis of patients with different molecular types, and evaluate the association between treatment regimens and offspring health.

This was a multicenter retrospective study on fertility outcomes and their prognosis and offspring health in young breast cancer patients. Based on the breast cancer database, the investigators registered the baseline data of young breast cancer patients (≤40 years old), including age at initial diagnosis, molecular typing, tumor stage, treatment plan, fertility protection measures, etc., and followed up by telephone/email and other means to collect their fertility status, recurrence and offspring growth and development data. The primary endpoints were the disease-free survival (DFS), overall survival (OS) after childbirth and childrens' growth and development. The secondary endpoints were the patient's fertility live birth rate, pregnancy outcomes and complications, use of fertility preservation techniques, breastfeeding status, etc. The investigators used the Kaplan-Meier method to draw the survival curve of the patients after childbirth, and analyzed the growth trajectory of the offspring born after diagnosis by the Lambda-Mu-Sigma method, and plotted the growth and development curve.The investigators used Log-rank to test the significance of differences in pregnancy rates between variables. The investigators used Univariate Cox regression analysis to screen factors related to prognosis, and then used multivariate Cox regression analysis to adjust for potential confounding factors to clarify independent prognostic indicators of disease. Finally, descriptive analyses were performed for other secondary outcomes.

Inclusion Criteria:

Only subjects who meet all of the following inclusion criteria can be enrolled in this trial:

1. Female patients diagnosed with breast cancer aged ≤ 40 years;
2. Patients with pathologically confirmed breast cancer, and TNM stage 0-III, the disease is in a stable or progressive state;
3. Complete medical records and clinical follow-up data were available. Informed consent.

Exclusion Criteria:

Anyone who has one of the following conditions cannot be included in this trial:

1. Female patients with a diagnosis age>40 years;
2. Stage IV breast cancer at first diagnosis;
3. The presence of other reproductive system diseases caused by oligomenorrhea or amenorrhea and infertility; Loss of clinical data or loss to follow-up.

Young breast cancer (≤40years)