Predictors and outcomes in breast cancer patients who did or did not pursue fertility preservation.

Breast cancer is the most common cancer in reproductive age women, and treatment can affect fertility; however, there is often concern regarding the safety of increased estradiol (E2) levels and potential delays in treatment with ovarian stimulation for fertility preservation (FP). The aim of this study was to compare recurrence and survival in breast cancer patients who pursued FP without concurrent letrozole to those who did not (non-FP). We reviewed charts of women with breast cancer who contacted the FP patient navigator (PN) at Northwestern University from 01/2005–01/2018. Oncology and fertility outcome data were collected. Data were analyzed by Chi-square test or regression, as appropriate. Kaplan–Meier curves were used to examine breast cancer recurrence and survival. Statistical analyses were performed with SPSS IBM Statistics 26.0 for Windows. 332 patients were included, of which 157 (47.3%) underwent FP. Median days to treatment after consulting the PN was 35 in the FP group and 21 in non-FP (p < 0.05). Cancer recurrence was noted in 7 (4.7%) FP patients and 13 (7.9%) non-FP patients (NS), and mortality in 5 (3.2%) FP patients and 7 (4.2%) non-FP patients (NS). Within the FP group, no significant differences were found in recurrence or mortality based on ER status, age, BMI, peak E2 level or total gonadotropin dose. Likelihood of pursuing FP was primarily a function of age and parity, and was not affected by breast cancer stage. To date, 21 have used cryopreserved specimens, and 13 (62%) had a live birth. FP is safe and effective in breast cancer patients, regardless of receptor status; E2 elevations and the 2-week delay in treatment start are unlikely to be clinically significant. These findings are unique in that our institution does not use concomitant letrozole during stimulation to minimize E2 elevations in breast cancer patients.