Two international studies presented at last week’s ESMO Congress 2024 in Barcelona showed no increase in recurrence or new breast cancers in women who breastfed after being treated for breast cancer, including those with a germline BRCA mutation (an inherited change in BRCA genes that significantly increases the risk of developing certain cancers, especially breast cancer).
Oncologist Eva Blondeaux, IRCCS Ospedale Policlinico San Martino, Genova, Italy, who presented one of the studies, said this indicates the possibility for these women “to achieve a balance between the needs of the mother and those of the baby”.
Given the hormone-driven nature of breast cancer, there were previously concerns about pregnancy and breastfeeding after the disease, as both involve changes in hormone levels. This was particularly true for women with the BRCA mutation, who remain at high risk of developing a second breast cancer in the other breast.
While recent studies showed that neither assisted reproduction treatments nor pregnancy is associated with increased risk of recurrence or new cases of breast cancers, including in women carrying a germline BRCA mutation, until now very little evidence was available on the feasibility and safety of breastfeeding for these women.
“I hope these new findings will improve the way we counsel these patients," said Blondeaux.
The international study followed up nearly 5 000 young women carrying a germline BRCA mutation who had survived breast cancer.
Nearly one in four of the 474 women who subsequently gave birth breastfed their baby; just under half were unable to breastfeed because they had had both breasts removed to reduce their future cancer risk.
After a median follow-up of seven years from giving birth, there was no difference in the number of breast cancer recurrences or new breast cancers in women who breastfed their baby compared with those who did not breastfeed (adjusted sub-distribution hazard ratio 1.08, 95% confidence interval 0.57-2.06, p=0.82). There was also no difference in disease-free survival or overall survival.
A second new study that expands the investigation beyond BRCA, addressing women with hormone receptor-positive early breast cancer, showed similar results, with no risks associated with breastfeeding.
“These results are key for women who want to become pregnant and breastfeed their baby after breast cancer,” said Dr Fedro Alessandro Peccatori, director of the Fertility & Procreation Unit at the European Institute of Oncology IRCCS, Milan, a co-author of the study.
“It’s time to start thinking of breast cancer survivors as women with the same rights, needs and possibilities as women who never had cancer,” he added.
“Doctors were worried about giving these women the chance of having babies, but we have shown that this is safe in the short term. Now, with this new information, we can debunk the myth that breastfeeding is neither possible nor safe for them. They can have a normal pregnancy and relationship with their baby, including breastfeeding.”
The international POSITIVE study included 518 women who temporarily interrupted their breast cancer treatment to have a baby; 317 had at least one live birth and nearly two in three of them breastfed (62%). At two years from the first live birth the proportion of women with breast cancer recurrence or new breast cancer was similar in those who breastfed (3.6%) as in those that did not breastfeed (3.1%).
Dr Maria Alice Franzoi, medical oncologist and researcher at Gustave Roussy, Villejuif, France, who was not involved in the study, said: “There was previously a lack of high-quality data regarding the feasibility and safety of breastfeeding in young women who have been treated for breast cancer. Until now, both they and healthcare providers lacked information on whether breastfeeding is feasible after breast cancer surgery, on the safety of pausing adjuvant treatments for breastfeeding and on the hormonal changes related to it.”
However, she cautioned that follow-up of the studies should, ideally, continue for longer.
“Data from these two studies will be extremely useful to guide our practical discussions with young women diagnosed with breast cancer,” she added.
“We should start thinking and discussing about survivorship care planning – including fertility preservation, pregnancy and breastfeeding for women who want to consider these options – at the time of diagnosis, so that they are prepared and empowered across the entire breast cancer journey for shared decision making.”
Study 1 details
Breastfeeding after breast cancer in young BRCA carriers: Results from an international cohort study
Eva Blondeaux, Virginia Delucchi, Elene Mariamidze et al.
Presented at ESMO 20234
Abstract
Background
Pregnancy after breast cancer (BC) diagnosis and treatment is safe for patients (pts) carrying germline BRCA pathogenic or likely pathogenic variant. No data so far are available on feasibility and safety of breastfeeding in BRCA carriers.
Methods
This was an international, multicentre, hospital-based, retrospective cohort study including BRCA carriers diagnosed with stage I-III invasive BC at age 40 years or younger between January 2000 and December 2020 (NCT03673306). Pts that delivered a child after BC, were divided into two groups: women who breastfed after delivery and those who did not. Locoregional and contralateral BC recurrences, disease-free survival (DFS) and overall survival (OS) were compared among the two groups.
Results
Among 4732 pts included in the study from 78 centers worldwide, 659 had a pregnancy after BC diagnosis, of whom 474 delivered a child. After delivery, 110 (23.2%) pts breastfed (median duration 5 months), 68 (14.4%) did not breastfeed, 225 (47.5%) underwent bilateral risk-reducing mastectomy before delivery (thus were unable to breastfeed) and 71 (15.0%) had unknown breastfeeding status. Compared to pts in the no breastfeeding group (n=68), those in the breastfeeding group (n=110) were more frequently nulliparous at the time of BC diagnosis (61.8% vs 45.6%, p=0.026) and did not report prior smoking habit (71.8% vs 57.4%, p=0.019). After a median follow up of 7.0 (IQR 3.6-10.5) years after delivery, no difference in cumulative incidence of locoregional and/or contralateral BC events between the breastfeeding (n=110) and no breastfeeding (n=68) groups was observed (adjusted sHR=1.08, 95%CI 0.57-2.06, p=0.82). Similarly, no impact of breastfeeding on DFS (adjusted HR=0.83, 95%CI 0.49-1.41, p=0.49) nor OS (9 OS events in patients that breastfed and 3 in those that did not breastfeed) was observed.
Conclusions
Our study provides the first evidence on the safety of breastfeeding after BC in young BRCA carriers. Our data suggest that breastfeeding is feasible and safe with no difference in locoregional recurrence or second primary BC events, emphasizing the possibility of achieving a balance between maternal and infant needs without compromising oncological safety.
Study 2 details
Breastfeeding in women with hormone receptor-positive breast cancer who conceived after temporary interruption of endocrine therapy: Results from the POSITIVE trial
Hatem Azim Jr, Samuel Niman, Fedro Alessandro Peccatori et al.
Presented at ESMO 2024
Abstract
Background
The POSITIVE trial demonstrated no increase in short-term risk of breast cancer (BC) events in women with hormone receptor–positive (HR+) early BC who temporarily interrupted treatment to attempt pregnancy, after receiving 18 – 30 months of adjuvant endocrine therapy (ET). No prior prospective data detail breastfeeding patterns and behaviours in women with previous BC, and little is known about the impact of breastfeeding on BC outcomes.
Methods
Breastfeeding was a secondary endpoint of the POSITIVE trial. The evaluable dataset consisted of women who had at least one live birth on study. Here we describe breastfeeding frequency, duration, and laterality, and estimate the cumulative incidence of BC events by breastfeeding status. For this analysis, we recalculated breast cancer free interval (BCFI) from the date of first live birth to first invasive local, regional, or distant BC recurrence or contralateral BC.
Results
At a median follow-up of 41 months, 317 patients gave birth, of whom 196 (62%) breastfed, a total of 232 babies. Breastfeeding was from the contralateral breast in all but 2 patients while only 38 patients (12%) breastfed from both breasts. The frequency of breastfeeding was higher in women older than 35 years of age (62.8% vs. 51.2%), with no prior children (85.4% vs. 71.7%) and who underwent breast-conserving surgery (66.3% vs. 30.6%). 103/196 (52.6%) breastfed their first child for >4 months (median 4.4 months) (95% CI: 4.0 – 5.3). Duration of prior ET and time from enrolment to first live birth were not associated with breastfeeding frequency or duration. Breastfeeding did not impact the BCFI (HR: 1.12, 95% CI: 0.28 – 4.5) with few reported events (N=9), of which 3 were local recurrences. At 2 years from the first live birth, the cumulative incidence of BCFI was 3.6% and 3.1% in the breastfeeding and non-breastfeeding groups, respectively.
Conclusions
In POSITIVE, nearly two-thirds of women who gave birth breastfed, including >50% for more than 4 months. No impact on BC-related events was observed although longer follow-up is warranted. These results are key for women who wish to pursue pregnancy and breastfeeding after BC.
See more from MedicalBrief archives:
Breastfeeding cuts breast cancer recurrence
Higher risk for second breast cancer in some women – US cohort study
Experts urge more caution before needless mastectomies
Pregnancy before 29 helps decrease later breast cancer risk