Effect of childbirth after treatment on long-term survival from breast cancer

Authors

  • H. M. Verkooijen,

    Corresponding author
    1. Centre for Molecular Epidemiology, Investigative Medicine Unit, National University Health System, Singapore
    2. Department of Epidemiology and Public Health, Investigative Medicine Unit, National University Health System, Singapore
    3. Geneva Cancer Registry, Geneva University, Geneva, Switzerland
    • Centre for Molecular Epidemiology, National University of Singapore, 16 Medical Drive, 117597 Singapore.
    Search for more papers by this author
  • G. H. Lim,

    1. General Clinical Research Centre, Investigative Medicine Unit, National University Health System, Singapore
    Search for more papers by this author
  • K. Czene,

    1. Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
    Search for more papers by this author
  • V. Bhalla,

    1. Ministry of Health, Health Promotion Board, Singapore
    Search for more papers by this author
  • K. Y. Chow,

    1. National Registry of Diseases Office, Health Promotion Board, Singapore
    Search for more papers by this author
  • K. P. L. Yap,

    1. Centre for Molecular Epidemiology, Investigative Medicine Unit, National University Health System, Singapore
    Search for more papers by this author
  • K. S. Chia,

    1. Centre for Molecular Epidemiology, Investigative Medicine Unit, National University Health System, Singapore
    2. Department of Epidemiology and Public Health, Investigative Medicine Unit, National University Health System, Singapore
    Search for more papers by this author
  • M. Hartman

    1. Centre for Molecular Epidemiology, Investigative Medicine Unit, National University Health System, Singapore
    2. Department of Epidemiology and Public Health, Investigative Medicine Unit, National University Health System, Singapore
    3. Department of Surgery, Investigative Medicine Unit, National University Health System, Singapore
    4. Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
    Search for more papers by this author

Abstract

Background:

This study quantified long-term absolute and relative mortality risks of survivors of breast cancer with subsequent childbirth.

Methods:

The Singapore Birth Register (n = 319 437), Swedish Multi-Generation Register (n = 11 million) and population-based cancer registries were linked to identify 492 women with childbirth after breast cancer. For these women, cumulative mortality risks and standardized mortality ratios (SMRs) were calculated and compared with those of 8529 women aged less than 40 years with breast cancer without subsequent childbirth, and with those predicted by Adjuvant! Online.

Results:

Women with subsequent childbirth had a lower 15-year cumulative overall mortality rate than other women with breast cancer (16·8 (95 per cent confidence interval (c.i.) 13·3 to 20·9) versus 40·7 (39·5 to 41·9) per cent), but a higher relative mortality risk than the background population (SMR 13·6, 95 per cent c.i. 10·6 to 17·3). Mortality risks decreased significantly with increasing interval between diagnosis and subsequent childbirth. Mean 10-year cumulative mortality risks of women with subsequent childbirth were within the range of 10-year mortality predicted by Adjuvant! Online for women with T1 N0 tumours in otherwise perfect health.

Conclusion:

This study reinforced the view that pregnancy after breast cancer is not detrimental to survival. However, women who gave birth after this diagnosis had substantially higher mortality risks than young women in the general population. This information may be a valuable addition to routine mortality estimates. Copyright © 2010 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.

Ancillary