Influence of stage and grade of breast cancer on fertility preservation outcome in reproductive-aged women

Research question: Does breast cancer spread and aggressiveness affect fertility-preservation results? Design: Retrospective cohort study of women with breast cancer undergoing fertility-preservation treatment. Inclusion criteria: age 18-38 years and use of gonadotrophin releasing hormone antagonist protocol; exclusion criteria: recurrent cancer, previous oncological treatment, previous ovarian surgery and known ovarian pathology. Stimulation cycle outcomes of women with low-stage breast cancer were compared with those with high-stage disease. Patients with low-grade (G(1-2)) were compared with those with high-grade (G(3)) malignancies. Primary outcome: total number of mature oocytes; secondary outcomes: oestradiol level and number of follicles wider than 14 mm on the day of trigger, number of retrieved oocytes and cryopreserved embryos. Results: The final analysis included 155 patients. Patients with high-grade tumours (n = 80; age 32 years [28-35]) had significantly lower number of mature oocytes compared with patients with low-grade cancer (n = 75; age 32 years [28-35]; seven mature oocytes [4-10] versus 13 mature oocytes [7-17]; P = 0.0002). The number of cryopreserved embryos was also lower in the high-grade group (three [2-5] versus five [3-9]; P = 0.02). Stage-based analysis revealed a similar number of mature oocytes in high-stage (n = 73; age 32 years [28-35]) compared with low-stage group (n = 82; age 33 years [28-35]; eight mature oocytes [4-13] versus nine mature oocytes [7-15]; P = 0.06). Conclusions: High-grade breast cancer has a negative effect on total number of mature oocytes and cryopreserved embryos.