Effects of controlled ovarian stimulation on toxicity of TAC chemotherapy in early breast cancer patients

Background: Oocyte and embryo cryopreservation, using controlled ovarian stimulation (COS), are common fertility preservation methodologies in breast cancer patients receiving gonadotoxic neo (adjuvant) chemotherapy (CT). The effects of COS and peak estradiol levels on CT-induced side effects are unknown. Patients and methods: Eighteen patients with stage II and III breast cancer underwent oocyte or embryo cryopreservation at Leiden University Medical Center before receiving docetaxel, adriamycin, and cyclophosphamide (TAC) CT (COS group). A control group (N=18) was retrospectively selected from breast cancer patients, aged between 18 and 40, who underwent TAC CT without fertility preservation. CT-induced toxicity in the 2 groups was compared using χ² analysis. Associations between peak estradiol levels and distinct stimulation protocols and side effects in the COS group were investigated by using regression analysis. Results: Patient characteristics between both groups were similar, except for a lower age in the COS group vs the control group (30.5 vs 35.2 years, P=0.005). No differences were seen in grade III/IV side effects between both groups. In the COS group, an increase in thrombopenia grade I/II was seen, while grade I/II stomatitis and constipation were significantly lower in the COS group as compared with the control group (P=0.006 and P=0.008, respectively). In the COS group, no association was found between the peak estradiol levels and distinct stimulation protocols and side effects of CT. Conclusion: COS prior to TAC CT was not associated with an increase in grade III/IV side effects. Interestingly, COS may have a protective effect on mucositis and constipation. Moreover, the peak estradiol levels and distinct stimulation protocols had no effect on grade III/IV side effects in our study.