Having a family is one of the most important achievements in a person’s life. However, for breast cancer survivors this can be particularly challenging. One of the main reasons is that still many people believe that having a pregnancy in a patient with a prior history of breast cancer can be associated with an increased risk of disease recurrence. Good morning ladies and gentlemen, my name is Matteo Lambertini and on behalf of my co-authors I’ll be presenting the long-term follow-up analysis from our multicentre study investigating the safety of having a pregnancy in patients with a prior history of breast cancer and specifically in those with oestrogen receptor positive disease.

Due to the current trend towards delayed childbearing, especially in Western countries, breast cancer in young women often occurs before the completion of reproductive plans. From the literature we know that approximately half of young breast cancer patients at the time of diagnosis desire to have a pregnancy. However, less than 10% actually manage to become subsequently pregnant. One of the main reasons for this finding,  as also shown by recent surveys, is that many patients and many physicians remain concerned about the potential detrimental prognostic impact of pregnancy in breast cancer survivors especially in those with ER positive disease that is the most hormonally driven form of breast cancer.

Considering that patients with ER positive disease remain at increased risk of long-term recurrences, meaning recurrences also after five years from initial diagnosis, prior results from our study that were published in JCO in 2013 with a relatively short follow-up might not have provided the needed reassurance regarding the safety of pregnancy in breast cancer survivors. For this reason we decided to update the results of our multicentre case-controlled study that was conducted across several institutions in Europe and with the collaboration of the International Breast Cancer Study Group. In this study we included more than 1,200 breast cancer patients diagnosed at the age of less than 50 years before 2007. As per study design, this was a case controlled study. For each case, so for each patient who had a pregnancy after breast cancer, we selected three controls, so patients with breast cancer without a subsequent pregnancy, and patients were matched according to baseline and treatment characteristics. The primary objective of the study was to look into the safety of pregnancy specifically in the cohort of patients with ER positive disease.

At the updated analysis after approximately ten years from initial breast cancer diagnosis no difference in disease free survival nor in overall survival were observed between patients with ER positive breast cancer who had a pregnancy after diagnosis as compared to those without a subsequent pregnancy suggesting the safety of pregnancy in patients with ER positive disease. When looking at the cohort of patients with ER negative disease no difference in disease free survival was observed and, interestingly, a significant better overall survival was observed for patients with ER negative breast cancer who had a pregnancy as compared to those without a subsequent pregnancy. Similar results when considering together ER positive and ER negative patients – no difference in disease free survival and better overall survival for patients who had a pregnancy.

We also performed three subgroup analyses of disease free survival according to pregnancy outcome, abortion versus completed pregnancy; pregnancy interval since diagnosis, so timing of pregnancy since breast cancer diagnosis, less than two years, more than two years; and breastfeeding status, yes versus no. The main message from this busy slide is that the safety of pregnancy in breast cancer survivors was observed independently of the pregnancy outcome, the pregnancy interval and the breastfeeding status meaning that abortion probably should not be considered as a therapeutic measure in these patients, that probably there is no optimal timing for patients to wait for trying to become pregnant but this timing should be individualised and that breastfeeding can be feasible and safe also in breast cancer survivors.

So the conclusions from our study are that the long-term results confirm that pregnancy after breast cancer can be considered safe, irrespective of ER status and so should not be discouraged, including in patients with ER positive disease. The safety of pregnancy after breast cancer was observed independently of the pregnancy outcome, the pregnancy interval and the breastfeeding status. We believe that our findings should serve as a strong basis for counselling women enquiring into the safety of having a pregnancy. These results, we believe, further strengthen the rationale of the ongoing POSITIVE study that is accruing patients worldwide. This is a study that is currently investigating the safety of temporarily interrupting endocrine therapy in patients with ER positive disease who wish to become pregnant, for trying to have a baby.

Before concluding I wanted to thank Dr Azim for the opportunity to be here today and the European Society for Medical Oncology for supporting my PhD at the Institut Jules Bordet in Brussels Belgium. And of course thank you very much for your interest in our study and your attention. Thank you.