Chemotherapy for Breast Cancer During Pregnancy

• Breast cancers during pregnancy:
  • Are often locally advanced due to delays in diagnosis, and many of these young patients will require chemotherapy
• Systemic treatment of breast cancer during pregnancy:
  • Involves special consideration of both the mother and the baby
• Data from a single-institution prospective study:
  • Reported on 40 pregnant women initially and updated their series years later to include 57 women:
    • Treated with FAC chemotherapy (5-FU, doxorubicin, and cyclophosphamide):
      • During the second and third trimesters
  • Investigators concluded:
    • This regimen to be safe as fetal malformations occurred only 1.3% of the time:
      • Which was similar to the rate of malformations seen in fetuses not exposed to chemotherapy
• Methotrexate is contraindicated in all trimesters:
  • As its method of action is as an antimetabolite and anti-folate agent
• Although limited data exist on taxane-based therapies:
  • The NCCN recommends that if needed:
    • It should be given with weekly dosing
• Anti-HER2 therapy with either trastuzumab or pertuzamab:
  • Is contraindicated during pregnancy:
    • With case reports associating oligohydramnios or anhydramnios with therapy
• First-trimester chemotherapy:
  • Is contraindicated based on:
    • An increased risk of:
      • Fetal malformation
      • Stillbirth
      • Miscarriage
• Second- and third-trimester chemotherapy:
  • Appears to be safe:
    • But may be associated with:
      • Intrauterine growth retardation
      • Prematurity
      • Low birth weight
• Chemotherapy:
  • Should not be given after 35 weeks’ gestation or within 3 weeks of planned delivery:
    • The median gestational age is 38 weeks with more than 50% of babies born by vaginal delivery
• Breastfeeding while on chemotherapy:
  • Is contraindicated due to excretion of drugs into breast milk

REFERENCES

1. National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines for Oncology: Breast Cancer. https://www.nccn.org/professionals/physician_gls/f_guidelines.asp Published January 2016. Accessed January 29, 2017.
2. Amant F, Deckers S, Van Calsteren K, et al. Breast cancer in pregnancy: Recommendations of an international consensus meeting. Eur J Cancer. 2010;46:3158-3168.
3. Briggs GG, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation. A Reference Guide to Fetal and Maternal Risk. 6th ed. Philadelphia, Pa: Lippincott Williams and Wilkins; 2006.
4. Gwyn K, Theriault R. Breast cancer during pregnancy. Oncology (Williston Park). 2001; 15(1):39-46.
5. Hahn KM, Johnson PH, Gordon N, et al. Treatment of pregnant breast cancer patients and outcomes of children exposed to chemotherapy in utero. Cancer. 2006:107(6):1219-1226.

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