Reports about pregnancy after cancer treatments are rather limited. This may be because the proportion of reproductive aged women with cancer is relatively low. In addition, cancer survivors may not attempt pregnancy, due to fertility problems (amenorrhea) and/or fear of recurrence.

Safety of pregnancy: recurrence risk

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The available data, generally reported in retrospective cohort studies, does NOT indicate an increased risk of recurrence of cancer in women who become pregnant after cancer.  This holds true even in women with hormone sensitive cancers, like breast cancer.  

  • Several studies have shown that overall survival is better for breast cancer survivors who subsequently conceived, possibly due to the “healthy mother” effect1.
  • A recent meta-analysis of 14 studies demonstrated that women who became pregnant after breast cancer had improved overall survival compared to women who did not become pregnant, with a pooled relative risk of 0.59 (95% CI 0.5-0.7)2.

Overall survival analysis of women who became pregnant after cancer. Adapted from Azim HA, Jr., Santoro L, Pavlidis N, et al. Safety of pregnancy following breast cancer diagnosis: a meta-analysis of 14 studies. Eur J Cancer;47:74-83.

Safety of pregnancy: offspring

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

One of the largest studies evaluating pregnancy outcomes in cancer survivors compared reproductive outcomes in men and women who had a history of childhood cancers as compared to their siblings3.

  • The partners of males who had received childhood cancer treatments did not have adverse pregnancy outcomes, in general.  Only treatment with non-alkylating chemotherapy increased the risk of low birth-weight offspring.
  • Females who received childhood cancer treatments who specifically received pelvic radiation had offspring that were more likely to be premature, have a low birth-weight, and be small for gestational age.  Receiving doxorubicin or daunorubicin increased the risk of low birth-weight, independently of pelvic radiation.
  • There were no apparent differences in the risks of congenital abnormalities, single-gene defects, or cytogenic abnormalities in survivors of childhood cancer, regardless of type of prior treatment. 

 

 

 

 

 

 

Adapted from Green DM, Sklar CA, Boice JD, Jr., et al. Ovarian failure and reproductive outcomes after childhood cancer treatment: results from the Childhood Cancer Survivor Study. J Clin Oncol 2009;27:2374-81.
  • In rodents, exposure to cyclophosphamide DURING folliculogenesis or fertilization results in a high rate of pregnancy failure and high malformation rate.  There are no studies in humans to date.  However, caution should be applied when considering ovarian stimulation during, or soon after, chemotherapy4

Incidence of malformations in the fetuses of mice mated at different time intervals (1-12 weeks) following injection with cyclophosphamide (75 mg.kg). Adapted from Meirow D, Epstein M, Lewis H, Nugent D, Gosden RG. Administration of cyclophosphamide at different stages of follicular maturation in mice: effects on reproductive performance and fetal malformations. Hum Reprod 2001;16:632-7.

Timing of pregnancy

 

 

 

 

 

Data is limited about when it is safe to consider pregnancy after treatment for cancer.  This decision is usually made in close collaboration between the patient, the oncology team, and the fertility specialist. 

  • One study looked at pregnancy outcomes and risk of recurrence in women who conceived after breast cancer diagnosis and treatment.  They found a survival benefit in women who waited at least 2 years after diagnosis to attempt conception1
  • In some cases, the team decides that waiting to consider pregnancy until the 5-year disease-free marker is prudent. 
    • In young women, or women who banked eggs or embryos prior to chemotherapy, this time-frame will not dramatically affect pregnancy rates. 
    • However, in women who will be in the late 30’s or 40’s when attempting conception (without banked eggs or embryos), five years may dramatically decrease chances of pregnancy.  In these cases, women should be counseled about the possible additional benefit of egg/embryo banking, even in cases when then do not require chemotherapy.

References

  1. Ives A, Saunders C, Bulsara M, Semmens J. Pregnancy after breast cancer: population based study. BMJ 2007;334:194.
  2. Azim HA, Jr., Santoro L, Pavlidis N, et al. Safety of pregnancy following breast cancer diagnosis: a meta-analysis of 14 studies. Eur J Cancer;47:74-83.
  3. Green DM, Sklar CA, Boice JD, Jr., et al. Ovarian failure and reproductive outcomes after childhood cancer treatment: results from the Childhood Cancer Survivor Study. J Clin Oncol 2009;27:2374-81.
  4. Meirow D, Epstein M, Lewis H, Nugent D, Gosden RG. Administration of cyclophosphamide at different stages of follicular maturation in mice: effects on reproductive performance and fetal malformations. Hum Reprod 2001;16:632-7.

About the Author

Jennifer Mersereau, MD, MSCI, is an reproductive endocrinologist in the University of North Carolina's Department of Obstetrics and Gynecology. As the Director of the Fertility Preservation Program, she has extensive experience guiding patients and physicians through the oncofertility experience.

This page was last updated March 14, 2012.