In light of her poor prognosis termination of the pregnancy was discussed with the patient and her husband. This option was declined by the parents and accordingly, mastectomy for local disease control was arranged with chemotherapy to commence after term fetal delivery.
Theoretical considerations for why pregnancy could be associated with more severe disease include: (a) increased level of circulating stimulatory hormones, (b) delay in diagnosis, (c) expanded extra-vascular and lymphatic capacity in the engorged breast, and (d) a relative maternal immuno-incompetence.
No studies have demonstrated a therapeutic role for abortion in altering the natural history of the disease. Biopsy and mastectomy can be well tolerated by mother and fetus with the risk of spontaneous abortion following general anesthesia only approximately 1%.
Chemotherapy has not been shown to cause congenital malformations when given in the second half of pregnancy. Due to the risk of thrombocytopenia, it should be avoided in the peripartum period. In a study involving 163 patients given chemotherapy in the first trimester there were 19 cases of fetal malformations (10.4%). However, 10 of these cases involved Aminopterin, an agent formerly used to induce abortion. Of the remaining 9 cases (5%), three woman had received radiation therapy during the first trimester and a fourth had radiation therapy just prior to pregnancy. Four of the women who produced malformed infants had also received chemotherapy prior to conception. Chemotherapy given during the second and third trimester did not increase the risk of teratogenesis.
The dose of Tc-99m MDP administered to this patient was reduced to 5 mCi. This would deliver approximately 1.3-1.8 mGy (125-180 mREM) to the fetus, assuming a constant maternal urinary bladder volume of 200 ml. This patient was encouraged to void frequently. Irradiation of the fetus below 50 mGy has not been observed to cause congenital malformations or growth retardation. The single exception is one report of ocular abnormalities at low absorbed doses. This finding is at variance with a massive amount of experimental and epidemologic literature.
At absorbed doses of 100 mGy, the risk of spontaneous abortion very early in pregnancy appears to be increased by 0.1-1%. If a linear extrapolation were valid then 10 mGy may increase the spontaneous abortion rate by 0.01-0.1%.
2) Simon JD. Update recommendations for pregnant women. JNM, December 1986.
3) McGuire WL, Dressler LG. The emerging impact of flow cytometry in predicting recurrence and survival in breast cancer: a review. J Nat Can Instit, 75.
4) Wallace CJ. Current problems in cancer. Vol VII, No. 9, March 1983.
J. Anthony Parker, MD PhD, firstname.lastname@example.org