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A single-group trial on young women with hormone receptor–positive early breast cancer, recently published on The New England Journal of Medicine, shows that among selected patients a temporary interruption of endocrine therapy could be safe and does not rise short term risk of breast cancer events. These data need to be confirmed in a longer follow-up by showing that therapy interruption and pregnancy do not aggravate the risk of longer-term recurrence, always present in women with receptor-positive breast cancer.
The multicenter International Breast Cancer Study Group study involved 516 women 42 years of age or younger (median age 37 years) who had had stage I, II, or III breast cancer (93.4% had stage I or II disease), had received adjuvant endocrine therapy for 18 to 30 months and desired pregnancy; they temporarily discontinuated endocrine therapy to attempt pregnancy. Among 497 women who were followed for pregnancy status, 368 (74.0%) had at least one pregnancy and 317 (63.8%) had at least one live birth; in total, 365 babies were born. At a median follow-up of 41 months (1638 patient-years of follow-up), 44 patients had a breast cancer event (defined as local, regional, or distant recurrence of invasive breast cancer or new contralateral invasive breast cancer), a result that did not exceed the safety threshold set as the occurrence of 46 breast cancer events during a period of 1600 patient-years of follow-up. The 3-year incidence of breast cancer events was 8.9% in the treatment-interruption group and 9.2% in the control cohort; the hazard ratio for a breast cancer event to be associated with pregnancy was 0.53. Among 415 patients who were disease-free for ≥ 2 years, 304 (73.3%) resumed endocrine therapy during the study period, approximately half resumed therapy within 26 months after treatment interruption. Among 111 women who had not resumed endocrine therapy at the time of the database lock, 88 (79.3%) reported that they were currently attempting to become pregnant, were actively or recently pregnant, or actively or recently breastfeeding. A total of 15.4% women had not resumed endocrine therapy by 48 months after interruption. «Prospective data on the risk of recurrence among women with hormone receptor–positive early breast cancer who temporarily discontinue endocrine therapy to attempt pregnancy are lacking», authors say. «Among selected women with previous hormone receptor–positive early breast cancer, a temporary interruption of endocrine therapy to attempt pregnancy did not confer a greater short-term risk of breast cancer events, including distant recurrence, than that in the external control cohort. Further follow-up is critical to inform longer-term safety», authors conclude.
A single-group trial on young women with hormone receptor–positive early breast cancer, recently published on The New England Journal of Medicine, shows that among selected patients a temporary interruption of endocrine therapy could be safe and does not rise short term risk of breast cancer events. These data need to be confirmed in a longer follow-up by showing that therapy interruption and pregnancy do not aggravate the risk of longer-term recurrence, always present in women with receptor-positive breast cancer.
The multicenter International Breast Cancer Study Group study involved 516 women 42 years of age or younger (median age 37 years) who had had stage I, II, or III breast cancer (93.4% had stage I or II disease), had received adjuvant endocrine therapy for 18 to 30 months and desired pregnancy; they temporarily discontinuated endocrine therapy to attempt pregnancy. Among 497 women who were followed for pregnancy status, 368 (74.0%) had at least one pregnancy and 317 (63.8%) had at least one live birth; in total, 365 babies were born. At a median follow-up of 41 months (1638 patient-years of follow-up), 44 patients had a breast cancer event (defined as local, regional, or distant recurrence of invasive breast cancer or new contralateral invasive breast cancer), a result that did not exceed the safety threshold set as the occurrence of 46 breast cancer events during a period of 1600 patient-years of follow-up. The 3-year incidence of breast cancer events was 8.9% in the treatment-interruption group and 9.2% in the control cohort; the hazard ratio for a breast cancer event to be associated with pregnancy was 0.53. Among 415 patients who were disease-free for ≥ 2 years, 304 (73.3%) resumed endocrine therapy during the study period, approximately half resumed therapy within 26 months after treatment interruption. Among 111 women who had not resumed endocrine therapy at the time of the database lock, 88 (79.3%) reported that they were currently attempting to become pregnant, were actively or recently pregnant, or actively or recently breastfeeding. A total of 15.4% women had not resumed endocrine therapy by 48 months after interruption. «Prospective data on the risk of recurrence among women with hormone receptor–positive early breast cancer who temporarily discontinue endocrine therapy to attempt pregnancy are lacking», authors say. «Among selected women with previous hormone receptor–positive early breast cancer, a temporary interruption of endocrine therapy to attempt pregnancy did not confer a greater short-term risk of breast cancer events, including distant recurrence, than that in the external control cohort. Further follow-up is critical to inform longer-term safety», authors conclude.
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