Effects of cancer stage and grade on fertility preservation outcome and ovarian stimulation response.

STUDY QUESTION: Do the stage and grade of malignancy affect the fertility preservation outcome in females?

SUMMARY ANSWER: Patients with high-grade cancer have a decreased number of retrieved mature oocytes and cryopreserved embryos.

WHAT IS KNOWN ALREADY: Cancer has local and systemic effects on the host. The effects of cancer spread and aggressiveness on the ovarian function and stimulation response remain unclear.

STUDY DESIGN, SIZE, DURATION: Retrospective cohort study evaluating data of all fertility preservation treatment cycles among women with cancer at the reproductive unit of the McGill University Health Centre in the period from 2008 to 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS: Study inclusion criteria were age 18-38 years, first stimulation cycle, GnRH-antagonist protocol and early follicular phase stimulation start. Only one stimulation cycle per patient was included. Patients with ovarian pathology, previous ovarian surgery and previous chemo- or radiotherapy were excluded. The outcomes of women with low-stage cancer (local tumor Stage I-II, no lymph node involvement, no metastases) were compared with those with high-stage disease (local tumor Stage III-IV, lymph node involvement or metastases). Similarly we compared those with low-grade (G1-2) and high-grade (G3-4) malignancies. The primary outcome measure was the number of mature oocytes retrieved. The secondary outcomes included the total number of retrieved oocytes, the number of vitrified oocytes, and the number of frozen embryos. We used Student's t-test for normally distributed data and Wilcoxon test for skewed data. To determine factors associated with good fertility preservation outcome defined as over 10 retrieved mature oocytes, we used multivariate logistic regression.

MAIN RESULTS AND THE ROLE OF CHANCE: A total of 147 patients were included in the final analysis. Age, body mass index, ovarian reserve parameters of the study groups in stage- and grade-based analyses were similar. Compared to women with low-stage cancer (n = 83), those with high-stage cancer (n = 64) required a higher dose of gonadotropin (P = 0.02). The number of retrieved mature oocytes (9 (7-13) versus 8 (5-12); P = 0.37) and vitrified oocytes (10 (7-15) versus 10 (7-13); P = 0.53) were similar between the two groups. However, in cycles where fertilization of all retrieved oocytes was performed, the fertilization rate (82.7% versus 71.5%; P = 0.03) and the number of vitrified embryos (6.2 ± 3.2 versus 4.3 ± 2.1; P = 0.01) were higher in the low-stage group. Compared to patients with low-grade cancer (n = 62), those with high-grade disease (n = 85) had significantly lower number of retrieved mature oocytes (11 (7-15) versus 8 (5-11); P = 0.002) and vitrified oocytes (12 (8-15) versus 10 (7-11); P = 0.005). The number of vitrified embryos was lower in high-grade group (6.5 ± 3.5 versus 4.6 ± 2.3; P = 0.03) in cycles where the fertilization was performed. In multivariate logistical analysis, the low-grade cancer was significantly associated with retrieval of over 10 mature oocytes (OR = 4.26; 95% CI 1.82-9.98; P = 0.0009).

LIMITATIONS, REASONS FOR CAUTION: The main limitations of the study include its retrospective design and the relatively small sample size in the embryological outcome analysis. The results of our study should be viewed with caution as different malignancy types were included in the study groups, although their distribution between the study groups was similar.

WIDER IMPLICATIONS OF THE FINDINGS: Cancer grade seems to have a negative impact on the fertility preservation outcome and the ovarian stimulation response.

STUDY FUNDING/COMPETING INTEREST(S): Authors have not received any funding to support this study. There are no conflicts of interest to declare.