Safe and successful pregnancy following breast cancer treatment in young patients 35 years old or under without invasive fertility preservation: a retrospective study.

PURPOSE: Recent advances in the treatment of breast cancer have led to the improvement of breast cancer patient's survival. With the prolonged survival of these patients, pregnancy became an important issue, especially in young cancer patient aged 35 years or under. Increased hormone levels during pregnancy, however, raise concerns about elevating the risk of cancer recurrence. The aim of this study was to validate the notion of increased risk associated with pregnancy after breast cancer treatment in young patients.

METHODS: From January 2009 to December 2020, newly diagnosed breast cancer patients 35 years old or under who underwent optimal surgery in Korea University Guro Hospital were enrolled in this study. Patients were categorized into 3 groups: nulliparous, pregnancy prior to treatment of breast cancer, and patients with pregnancy after breast cancer treatment. Their overall survival and disease-free survival were evaluated.

RESULTS: A total of 107 patients were enrolled in this study. Thirteen patients (12.1%) conceived and successfully delivered. The mean follow-up period after surgery was 58.9 (± 33.5) months. There was no significant difference in overall survival (P = 0.608) and disease-free survival (P = 0.591) among different groups.

CONCLUSION: In young patients, pregnancy after treatment for breast cancer did not affect their overall survival or diseasefree survival as compared to nullipara or previously delivered groups. Therefore, pregnancy counseling should not be prevented in young breast cancer patients 35 years old or under.