Breastfeeding safety after breast cancer

9th October 2024

The first evidence of breastfeeding being safe and feasible after breast cancer was presented in two international studies at the recent European Society for Medical Oncology (ESMO) Congress 2024.

No increase in recurrence or new breast cancers was observed in women who breastfeed after being treated for breast cancer, the studies found.

The first study looked at breastfeeding after breast cancer in young mothers who carried BReast CAncer (BRCA) susceptibility genes. The international retrospective cohort study included women diagnosed with stage 1-3 invasive breast cancer at age 40 or younger between Jan 2000 and Dec 2020.

Using statistical analysis, the researchers compared whether breast cancer returned and how long individuals lived, with or without cancer, in women with the BRCA gene and those without.

Nearly 5,000 women participated in the study, resulting in 659 pregnancies and 474 women delivering a child. After delivery, 23.2% of the women breastfed for a median duration of five months, 14.4% did not breastfeed and 47.5% were unable to breastfeed due to undergoing a double mastectomy before pregnancy. The remaining participants (14.9%) had unknown breastfeeding status.

After a median follow-up of seven years, there was no significant difference in the number of locoregional or contralateral breast cancer recurrences between women who breastfed and those who did not (adjusted sHR=1.08, 95%CI 0.57-2.06, p=0.82). In addition, breastfeeding had no impact on disease-free survival (adjusted HR=0.83, 95%CI 0.49-1.41, p=0.49) or overall survival (OS), with nine OS events in patients that breastfed and three in those who did not breastfeed.

In the second study, part of the POSITIVE trial, the researchers investigated a secondary endpoint of breastfeeding in women with hormone receptor-positive early breast cancer who had temporarily interrupted treatment to attempt pregnancy after receiving 18-30 months of adjuvant endocrine therapy.

The primary endpoint had been whether this temporary interruption of treatment was safe, and the researchers found no increase in short-term risk of breast cancer events in these women.

At a median follow-up of 41 months, 317 patients had given birth, of whom 196 (62%) breastfed a total of 232 babies.

Breastfeeding did not impact the breast cancer-free interval (BCFI) with few reported events in women who breastfed (n=9/196). Two years after the first live birth, the cumulative incidence of BCFI was 3.6% and 3.1% in the breastfeeding and non-breastfeeding groups, respectively.

It was concluded that while longer follow-up is warranted, both studies provide key evidence for clinicians and women with breast cancer who wish to pursue pregnancy and breastfeed.

Indeed, commenting on the findings, Dr Maria Alice Franzoi, medical oncologist and researcher at Gustave Roussy, Villejuif, France, who was not involved in the studies, said: ‘Data from these two studies will be extremely useful to guide our practical discussions with young women diagnosed with breast cancer.

‘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.’

References
Blondeaux, E et al. Breastfeeding after breast cancer in young BRCA carriers: results from an international cohort study. Abstract 1815O, presented at the ESMO Congress 2024; Sept 14, Proffered Paper Session on Saturday, 14 September, 14:45-16:25 (CEST) in the Pamplona Auditorium – Hall 3.

Azim, HA et al. Breastfeeding in women with hormone receptor-positive breast cancer who conceived after temporary interruption of endocrine therapy: Results from the POSITIVE trial. Abstract 1814O. presented at the ESMO Congress 2024; Sept 14, Proffered Paper Session on Saturday, 14 September, 14:45-16:25 (CEST) in the Pamplona Auditorium – Hall 3.

Breastfeeding linked to reduced risk of maternal cardiovascular disease

28th January 2022

Breastfeeding has been found to be associated with a reduced risk of maternal cardiovascular disease levels in later life

Breastfeeding mothers have a lower risk of subsequent cardiovascular disease in later life according to a meta-analysis by researchers from the Department of Neurology, Clinical Epidemiology Team, Medical University of Innsbruck, Innsbruck, Austria.

The World Health Organization has decreed that ‘breastfeeding is one of the most effective ways to ensure child health and survival‘ adding how breastmilk is an ideal food for infants as it is safe, clean and contains antibodies which help protect against many common childhood illnesses.

Despite this perceived value, a 2019 analysis of breastfeeding in low and middle incomes countries, revealed how only 37% of children under 6 months of age are exclusively breastfed.

While there are clear benefits to children, breastfeeding also appears to benefit the health of lactating mothers, with one review identifying how breastfeeding for longer than 12 months was associated with a 26% reduced risk of breast cancer and a 32% reduced risk of ovarian cancer. In 2021, a statement from the American Heart Association, suggested that ‘lactation and breastfeeding may lower a woman’s later cardiometabolic risk‘.

Furthermore, an umbrella review of the association between maternal health and cardiovascular disease in later life, also suggested an inverse association between length of lactation and morbidity or mortality from cardiovascular disease but did not provide a pooled estimate of this association.

For the present study, the Austrian team undertook a systematic literature review and meta-analysis to more precisely characterise the association between breastfeeding and the development of maternal cardiovascular events. They compared ‘ever’ versus ‘never’ breastfeeding in relation to cardiovascular disease (CVD), coronary heart disease (CHD), stroke or fatal CVD and calculated hazard ratios for each of these outcomes.

Findings

The team identified 8 relevant prospective studies which included 1,192,700 women with a mean age of 51.3 years, of whom 82% reported having ever breastfed for a mean duration of 15.6 months.

There was a significant 11% reduced risk of maternal CVD among those breastfeeding compared to who did not (Hazard ratio, HR = 0.89, 95% CI 0.83 – 0.95). Similarly, significant reductions were also observed among those breastfeeding for CHD (HR = 0.86), stoke (HR = 0.88) and fatal CVD (HR = 0.83).

The authors calculated that each additional year of breastfeeding resulted in significant reduced risk, based on hazard ratios, for CVD (HR = 0.91) and CHD (HR = 0.89) and although the risk for stroke was reduced (HR = 0.91) this was non-significant.

Commenting on these results, the authors noted how the relationship between breastfeeding and cardiovascular risk had been overlooked for a long time and that in general, the maternal health benefits are less well known. They suggested that interventions to promote and facilitate breastfeeding should be reinforced.

Citation

Tschiderer L et al. Breastfeeding Is Associated With a Reduced Maternal Cardiovascular Risk: Systematic Review and Meta‐Analysis Involving Data From 8 Studies and 1 192 700 Parous Women. J Am Heart Assoc 2022