Original articlePregnancy-associated breast cancer and pregnancy following treatment for breast cancer, in a cohort of women from Victoria, Australia, with a first diagnosis of invasive breast cancer
Introduction
The overall impact of pregnancy on the lifetime risk of breast cancer (BC) is considered to be protective, although protection may be limited to those women who were young at the time of their first completed pregnancy and those with hormone receptor positive disease.1, 2 In the short-term, pregnancy and the post-partum period are associated with an increased risk of BC. The period of increased risk has been estimated to range between 10 and 15 years following a first pregnancy in a young woman,3 to a period as long as 30–50 years for a woman whose first pregnancy occurs in her 30's,3 possibly explaining the difference in lifetime risk of BC in relation to age at first birth.4 Despite these protracted estimates of the duration of increased risk of BC following pregnancy, the definition of pregnancy-associated BC (PABC) is generally limited to BC diagnosed during, or within the 12 months following, pregnancy,3, 5, 6, 7 despite the suggestion that a longer time period should be used8 or that cancer which develops during lactation should be included, irrespective of the time that has elapsed since pregnancy.3
Given that the incidence of BC amongst young women is relatively low9 and that pregnancy is associated with an increase in risk, PABC has the potential to make an important contribution to all cases, in women of reproductive age.
Conversely, with women delaying childbearing,10 increasingly the diagnosis of BC is made in a woman who has either not completed, or in some cases, not even started her desired family. Although retrospective data suggest that pregnancy is safe after BC and may even lead to improved survival,11, 12 prospective studies are needed.13, 14
The Bupa Health Foundation Health and Wellbeing After Breast Cancer Study (Bupa Study) is a prospective questionnaire-based study of 1683 women diagnosed with their first episode of invasive BC between June 2004 and December 2006. In this report we have examined PABC as well as pregnancy following the treatment of BC, in women followed for nearly 6 years after diagnosis.
Section snippets
Materials and methods
The majority (78%) of participants in the Bupa Study were recruited through the Victorian Cancer Registry with the remainder of recruits volunteering directly to our research program in response to advertisements about the study.15 The women completed an enrolment questionnaire (EQ) within 12 months of diagnosis and then completed an annual follow-up questionnaire (FQ) for 5 years following completion of their EQ. The study was entirely questionnaire-based with the questionnaires mailed to
Results
1683 women were recruited to the study and of these, 1305 completed FQ5. 122 women died during the study, 10 were lost to follow-up and 246 withdrew from the study prior to completion of FQ5.
Discussion
In our study, women with PABC made up 3.3% of women younger than 48 years at diagnosis, but in women younger than 35 years, 14.3% were PABC.
The mean age of women with PABC has been reported to range between 32 and 38 years.16 Some studies have only included women under 35 years,7, 17 43 years7 or 45 years.18 Our study included women aged up to 48 years, as did the study by Murphy et al.19 Although the proportion of women with PABC diagnosed under the age of 35 years appears to be consistent
Conclusion
Women of child-bearing age should be informed that their risk of developing BC is elevated during and after pregnancy and if women are concerned about a change in their breasts they should seek medical advice.
As the age at first birth increases, the proportion of women diagnosed with breast cancer, who have not started, or completed their families, is likely to increase, so that considerations of fertility in relation to treatment, will become increasingly important.
Ethical approval
The Bupa Study was approved by the Ethics Committee of the Cancer Council of Victoria and the Human Ethics Committee of Monash University and all participants provided written informed consent.
Funding sources
This work was supported by the BUPA Health Foundation (previously the Medical Benefits Fund of Australia Limited Foundation) (to SRD and RJB), the National Health and Medical Research Council of Australia (Grants no. 219279 to SRD and RJB, 490938 to SRD), Novartis Oncology Australia, the L.E.W. Carty Trust, the Jack and Robert Smorgon Families Foundation, Connie and Craig Kimberley and Roy Morgan Research (all to SRD and RJB). This Research Project was also supported by the Victorian Government
Conflict of interest statement
No authors have any conflict of interest to declare in relation to this work.
Acknowledgements
The authors wish to thank the study participants and the members of our Study Advisory Group: Dr Jacquie Chirgwin, A/Professor John Collins, Professor Graham Giles, Mr Peter Gregory, Mr Stewart Hart, Miss Suzanne Neil and Mrs Avis McPhee. The authors also wish to thank members of the research team of the Health and Wellbeing After Breast Cancer study, without whose hard work this large cohort study would not be possible (Maria La China and Jo Bradbury).
Finally, we thank Ms Helen Farrugia,
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Pregnancy-associated breast cancer (PABC) and fertility issues in young women after breast cancer
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2019, Ciencia e Saude Coletiva
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