In general, evidence-based guidelines include recommendations against discouragement of future pregnancies in young women diagnosed with early-stage breast cancer, given the absence of an association between pregnancy and breast cancer recurrence. However, fertility rates have been shown to be lower in young breast cancer survivors compared with matched control individuals.
Fertility-related decisions for women with a history of early-stage breast cancer may be complicated by the long-term use of endocrine therapy and ovarian suppression therapy, during which pregnancy may be contraindicated or precluded, respectively. Nevertheless, many questions remain regarding the interest of these women in future pregnancies, as well as their pregnancy-related outcomes.
This analysis of data from a prospective, multicenter cohort study included 1026 women diagnosed with stage 0 to 3 breast cancer at age 40 years or less between 2006 and 2016. Surveys regarding fertility interest and reproductive outcomes were completed by study participants at baseline with a median time period between breast cancer diagnosis and return of the baseline survey of 5.1 months, and then every 6 months for the first 3 years of follow-up, followed by once yearly. Data related to patient-, disease-, and treatment-related characteristics were abstracted from patient medical records.
At disease diagnosis, he median patient age was 37 years, the nulliparous rate was 38.6%, and 56.7%, and 65.5% of patients were diagnosed with stage 2/3 disease and receiving oral endocrine therapy at baseline, respectively. The median duration of follow-up was 5 years.
A key finding was that 368 (36%) of study participants reported that they wished to become pregnant on at least 1 survey conducted within 5 years from breast cancer diagnosis, and this rate was significantly higher among nulliparous women compared with women with children prior to diagnosis of breast cancer (68% vs 19%; P <.0001).
While only 126 (34%) of the women who expressed a desire to become pregnant actually attempted pregnancy, 89 (71%) of this subgroup reported a pregnancy.
Of the 152 pregnancies reported within 5 years of breast cancer diagnosis in a total of 108 women, 57.5%, 31%, 7%, and 0.6% were classified as live births, miscarriages, terminations, and stillbirths, respectively, with the remainder pending follow-up.
“Therefore, patients interested in future fertility at diagnosis can be counseled that many young breast cancer survivors remain fertile and can become pregnant,” the study investigators noted.
On multivariable analyses of the subgroup of women who became pregnant, characteristics such as younger vs older age (P <.0001), being nulliparous vs not (P =001), having a partner vs not (P =.0002), and not receiving vs receiving endocrine therapy (P =.001) were independently associated with pregnancy. However, neither receipt of chemotherapy nor the presence of a deleterious germline BRCA1/2 mutation were associated with pregnancy in this subgroup.
Of note, 65 of the women who became pregnant within 5 years of breast cancer diagnosis had estrogen receptor-positive disease. Among the 47 women in this subgroup who initiated endocrine therapy, there was evidence that 31 resumed endocrine therapy at a later date.
Of the 738 women with 4-year follow-up survey data, only 4% reported undergoing infertility treatments after breast cancer diagnosis.
Some of the limitations of this study mentioned by the study investigators included the need for longer-term follow-up of reproductive outcomes, particularly in women receiving endocrine therapy, as well as the possibility of response bias.
“Although consensus guidelines have focused on the pretreatment period for fertility discussions to facilitate informed decision making regarding cancer treatment and fertility preservation options, these findings highlight the importance of continued discussion of fertility plans during survivorship,” the study investigators emphasized.
They further added that “future work within this prospective cohort will evaluate fertility interest, pregnancies, and the use of fertility preservation later in survivorship, with the goal of generating additional data to help young women with breast cancer make decisions to balance the dual goals of treating their breast cancer and completing their families.”
Poorvu PD, Gelber SJ, Zheng Y, et al. Pregnancy after breast cancer: Results from a prospective cohort of young women with breast cancer. Cancer. Published online December 1, 2020. doi:10.1002/cncr.33342