Preserving fertility in young women undergoing chemotherapy for early breast cancer; the Maastricht experience

We performed a prospective cohort study in patients who visited the Maastricht University Medical Centre for counseling on FP in the years 2008–2015. Premenopausal patients aged under 41 years with stage I–III invasive breast cancer with an indication for adjuvant or neoadjuvant systemic treatment who were potentially interested in FP were referred. Patients were offered the option of embryo and/or oocyte cryopreservation. None of the patients received prophylactic GnRH analogs during chemotherapy. Our controlled ovarian stimulation protocol is according to the protocol described by Oktay et al. and von Wolff et al. [18, 19] According to the Netherlands Central Committee on Research Involving Human Subjects guidelines, this observational study is not subject to the Act on Medical Research Involving Human Subjects.

For each patient, the following characteristics were collected: date of first visit, age, gene mutation status and date, (male) partner at time of diagnosis, age and number of children at diagnosis if applicable, known infertility before treatment, primary tumor characteristics, type of local breast cancer treatment, chemotherapy, human epidermal growth factor receptor 2 (HER2)-targeted therapy and endocrine therapy if applicable, choice of FP procedure, number of oocytes retrieved, and number of embryos and oocytes frozen. During follow-up, we collected data on OFR, date of live birth, date of last update, first local, regional or distant breast cancer recurrence or the occurrence of a contralateral breast cancer, and survival status. Data collection from the medical files was last updated in 2018, therefore the follow-up duration was at least 2 years.

We aimed to assess the uptake of FP in young women with early-stage breast cancer referred for counseling to the Maastricht University Medical Centre from 10 affiliated centers in the Southeast of the Netherlands in the years 2008–2015, and to assess the OFR-rate after end of chemotherapy, the live birth rate, and the disease-free survival rate since the date of counseling.

Premenopausal status at counseling was based on a history of regular menstruation. In patients using oral contraceptives, we presumed a premenopausal status based on a regular menstrual cycle before oral contraceptive use and the young age at counseling [20]. Furthermore, before the start of hyperstimulation, we performed a vaginal ultrasound to count the antral follicles and measured Anti-Mullerian Hormone to predict the ovarian reserve. Uptake of FP was defined by the number of women who underwent FP as numerator and the number of counseled women as denominator. Premenopausal status after chemotherapy (OFR) was based on menstrual cycles and/or premenopausal lab values. History and FSH/17-ß-estradiol assessments were locally performed at the end of chemotherapy and 3-monthly thereafter. Time to OFR was defined as the interval from the end of chemotherapy to the date of premenopausal status confirmation (set at 0.1 months if present at the end of chemotherapy). Hence, OFR is a composite endpoint consisting of both recovery and maintenance of ovarian function during chemotherapy, as one may consider it equally relevant from a patient perspective when estimating on forehand the risk of infertility. The rate of live birth was defined as the percentage of women that gave birth to one or more babies excluding still birth and miscarriage. The time to live birth was defined as the interval from the date of counseling to the first live birth. The mode by which the pregnancy leading to live birth was achieved was categorized as either spontaneous, by use of earlier cryopreserved embryos or oocytes, or by fertility treatments. The period of disease-free survival was defined as the interval from the date of counseling to ipsilateral invasive breast tumor recurrence, regional breast cancer recurrence, distant recurrence, contralateral breast cancer, second primary non-breast invasive cancer, or death attributable to any cause, whichever occurred first [21].

Baseline characteristics of the FP group and the non-FP group were compared using independent samples Student t tests for normally distributed continuous variables, the Mann–Whitney-U test for skewed continuous variables, and the chi-square test for categorical variables. Kaplan–Meier analyses were performed for OFR (one minus Kaplan–Meier estimator) and disease-free survival, for disease-free survival comparing the FP group and the non-FP group by using the logrank test. Cumulative incidence of live birth was determined using competing risk analyses. For the endpoint of OFR, patients were censored at the date of ovariectomy, start of gonadotropin-releasing hormone treatment in the absence of OFR, recurrent disease or last follow-up. In patients with OFR for whom the exact date of OFR was not known (n = 13), we assumed the group median as time to OFR to prevent exclusion of these patients and an underestimation of the OFR-rate. For the endpoint of live birth rate, patients were censored at the end of follow-up. The occurrence of a disease-free survival event and ovariectomy, both hindering the observation of live birth, were therefore considered as competing risks. All statistical analyses were performed with SPSS 22.0 and STATA 14.1. A P value of < 0.05 was considered statistically significant.

In the period 2008–2015, 125 women with the diagnosis of early breast cancer were referred for FP counseling. After excluding seven patients because of several reasons, 118 patients were analyzed in this study (Fig. 1).

Patient, tumor, and treatment characteristics are shown in Table 1. The median age of the counseled women was 31 years (range 19–40). At diagnosis, 75% of patients had a male partner and 31% had one or more children. Of all patients, 84% were analyzed for germline mutations. In 19% of patients, a germline mutation was present, corresponding with 23% of tested patients. The median tumor size was 22 mm (range 7–100) with slightly more than half of the patients having lymph node-negative disease. Almost two-third of the patients had a grade III tumor. The hormone receptor status was positive in 53% and the HER2 status was positive in 25%. The median follow-up in the FP group was 52 months (95% confidence interval (CI) 48–58), the median follow-up in the non-FP group was 51 months (95% CI 42–63).

Thirty-four (29%) women underwent FP before the start of chemotherapy. Patients who underwent FP had less often children (85% versus 63%, P = 0.03), more often a male partner (88% versus 70%, P = 0.06), and more often smaller tumors (19 mm versus 25 mm, P = 0.04) compared with those who did not undergo FP (Table 1).

In 33 of the 34 (97%) patients who pursued FP, embryos or oocytes could be cryopreserved. In one patient only one oocyte was obtained, which could not be fertilized. In 25 patients embryos were frozen and in seven oocytes. One patient chose to preserve both embryos and oocytes. Per patient a median of four embryos (range 1–17) and seven oocytes (range 2–13) were cryopreserved. In three patients, two cycles of oocyte retrieval were necessary, the other patients underwent one cycle.

In all but four patients menses was stopped during chemotherapy. Median time to OFR was 9 months (range 0–83 months). The 2-year OFR-rate was 68% (95% CI 59–77%). The 5-year OFR rate was 92% for the total group of counseled patients (Fig. 2).

Live birth occurred in 26 women. All pregnancies occurred at least 2 years after the diagnosis of breast cancer. The 5-year live birth rate was 27% (95% CI 17–38%, Fig. 3). Of the 26 women giving live birth, eleven had estrogen receptor-positive disease.

Ten women in the FP group gave birth to twelve babies. Eleven babies were healthy, one had a congenital anomaly (M. Hirschsprung).

Only three women applied for transfer of cryopreserved embryos. Two of these women asked for PGD of the frozen embryos because they had a germline mutation in the BRCA1 gene, although both had OFR. Both women became pregnant after transfer of an embryo without the BRCA1 mutation. One other woman did not conceive after thawing of 10 and transfer of 8 embryos. Also, her attempts to achieve a spontaneous pregnancy were not successful. Another patient was supported by intrauterine insemination (IUI) to become pregnant. The other nine pregnancies in this group were spontaneous pregnancies.

Sixteen women in the non-FP group gave birth to twenty healthy babies. All but one pregnancy in this group were spontaneous. One woman conceived via IVF after breast cancer treatment. One woman did not become pregnant despite OFR and the use of IVF and IUI.

Disease events were detected in fifteen patients. The 5-year disease-free survival rate was 85%. In the FP group, two patients developed distant metastases, of whom one is deceased, one patient had a loco-regional recurrence. In the non-FP group (n = 84), twelve women developed distant metastases, of whom four were deceased. For women in the FP group, the 5-year disease-free survival rate was 85% and for women in the non-FP group, the rate was 84% (logrank P = 0.42, Fig. 4).