Pregnancy outcomes in breast cancer survivors; meta-analysis

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Published: 10 Dec 2020
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Dr Matteo Lambertini - San Martino Hospital, Genoa, Italy

Dr Matteo Lambertini speaks to ecancer at the SABCS Virtual Congress 2020 about the fertility of young breast cancer survivors.

He opens by presenting the problem that there is a low number of women able to conceive after breast cancer treatment.

Dr Lambertini outlines a meta analysis of 39 studies over 8 million women, and explains the objectives and results found.

He concludes that pregnancy after breast cancer should be considered safe, but should be closely observed.

 

Returning to a normal life should be considered as a crucial ambition in cancer care in the twenty-first century. In young cancer survivors this includes the possibility to complete family planning following treatment completion. Indeed, fertility and pregnancy related issues are among the top priority areas of concern for young breast cancer survivors, and according to international guidelines on fertility preservation and post-treatment pregnancies, these topics should be discussed at the time of diagnosis and during oncology follow-up with all young cancer patients. However, we know that only a few women with prior history of breast cancer are able to conceive following treatment completion. Patients’ and physicians’ safety concerns are among possible explanations for these low pregnancy rates.

To provide updated evidence on this important topic, we performed a systematic review and meta-analysis summarising the results of all the available studies that address the issue of pregnancy after breast cancer. We are presenting these results at the 2020 San Antonio Breast Cancer Symposium. In this meta-analysis we included 39 studies with more than eight million women, of whom 115,000 had a prior history of breast cancer and among them 7,500 had a pregnancy following treatment completion.

We addressed three important objectives. The first one was chances of pregnancy after breast cancer by comparing young breast cancer survivors to the healthy women from the general population and to survivors from other cancers. Here we observe that young breast cancer survivors have around 60% lower chances of having a future pregnancy as compared to the general population of a similar age. Among cancer survivors only cervical cancer survivors had lower chances than breast cancer patients to have a subsequent pregnancy. Safety concerns are a possible explanation for this low pregnancy rate in breast cancer survivors, being breast cancer a hormonally-driven form of tumour, and we hope that the other two results of our meta-analysis will be helpful to dispel these concerns.

The second objective was reproductive outcomes to address the safety of pregnancy from the baby’s side by comparing the pregnancies of young breast cancer survivors to those of healthy women from the general population. We observed no significant increase of major malformation nor of the majority of pregnancy and delivery complications. We observed a significant increased risk of pre-term delivery, caesarean section, small for gestational age, and pre-term birth, and this is why these pregnancies should be followed more closely as compared to what is normally done for the pregnancies of healthy women from the general population. The risk of developing these four complications appears to be higher for women that had a prior exposure to chemotherapy.

The third and final important objective was to address the safety of pregnancy after breast cancer from a maternal side. We included studies that compared survival outcomes, disease-free survivals and overall survivals between breast cancer patients with or without a subsequent pregnancy following treatment completion. We could not observe any detrimental prognostic effect for pregnancy after breast cancer, with actually a better disease-free survival and overall survival for women with a subsequent pregnancy as compared to those without subsequent pregnancy. This result was observed also after correcting for the potential so-called “healthy mother” effect, providing reassurance for women wishing to have a pregnancy following treatment completion. The safety of pregnancy after breast cancer from the mother’s side was observed irrespective of patient baseline characteristics including BRCA status, nodal status, prior exposure to chemotherapy, as well as pregnancy outcomes, so pregnancy interval, as well as pregnancy outcomes in terms of abortion or pregnancy completion, meaning that abortion is not therapeutic in these patients.

We really hope that these results will be helpful to improve the onco-fertility counselling of young breast cancer patients and to dispel the safety concern that we have on this topic. We can conclude that, based on this large international meta-analysis, of course after adequate treatment follow-up, pregnancy after breast cancer should be considered safe, should not be contraindicated in these patients, but we need to follow more closely these pregnancies, especially in women with prior exposure to chemotherapy.