Treating a pregnant woman diagnosed with breast cancer is a difficult clinical scenario facing a variety of clinicians, obstetricians, radiologists, surgeons, medical oncologists, and radiation oncologists, just to name a few. Unfortunately, there is a paucity of randomized, clinical trial data to guide the treating physicians.1,2 Thus the clinicians must rely on retrospective data and clinical experience to determine an individual patient’s treatment plan. This chapter will summarize the best currently available evidence for treating a pregnant woman with breast cancer.

The traditional definition of pregnancy-associated breast cancer (PABC) is that the diagnosis of breast cancer is made during pregnancy or within 1 year afterwards. Using this definition, epidemiologic data demonstrate that a breast cancer is diagnosed once in every 3000 pregnancies.3 The median age of pregnant women affected with breast cancer is 33 years (range, 23-47 years).2,4 As more and more women are delaying motherhood until their 30s or even 40s,5 PABCs should be increasing, but convincing epidemiologic data are not yet available.

Historically, PABC patients had a dismal prognosis. Kilgore and Bloodgood6 reported no survivors, whereas Haagensen and Stout7 reported an 8.6% overall 5-year survival rate, and White8 reported a 17% 5-year survival rate.

Harrington9 is credited with reviving at least a bit of optimism for these patients in 1937 by demonstrating a 61% 5-year survival rate among patients with negative lymph nodes. However, the majority of PABC patients present with metastatic disease in the regional nodal basin.10 When compared with age-matched, nonpregnant peers, the node-negative and node-positive 5-year survival is quite similar.11 Petrek et al11 reported that patients with PABC with tumor-free lymph nodes had an 82% 5-year survival rate, compared with an 82% rate for their nonpregnant counterparts. The pregnant patients with tumor-involved lymph nodes had a 47% 5-year survival rate compared with a 59% rate in the control patients; the difference was not statistically significant. This similar survival rate between pregnant breast cancer patients and their nonpregnant peers has been confirmed by others12-15 (Table 89-1).

The homogeneously dense breast tissue in pregnant and lactating women makes routine screening methods almost useless because little information is gained owing to the increased water content and loss of fat in the breast during pregnancy.16 If a dominant breast mass is detected on self-exam or clinician exam, then diagnostic mammograms can be performed with minimal risk to the fetus with the use of abdominal shielding and might yield important information regarding suspicious microcalcifications or masses. Ultimately though, sonography is probably the imaging method of choice for imaging the breasts of pregnant women. Breast sonography provides a rapid and accurate method of differentiating cystic lesions from solid masses during pregnancy and poses no risk to the developing fetus.17 Gadolinium-enhanced breast magnetic resonance imaging (MRI) is increasingly used for staging and treatment decisions in breast cancer,18 but gadolinium is contraindicated during pregnancy because it crosses the placenta. Thus a noncontrast MRI does not improve the diagnostic accuracy for the breast radiologist.

In pregnant women with breast abnormalities noted on clinical or radiologic examinations, the goal is to make an accurate pathologic diagnosis of the abnormality with the least invasive method. There is controversy surrounding each diagnostic method. The least invasive diagnostic method would be a fine-needle aspiration (FNA), but this may be associated with both increased false-positive19 and increased false-negative rates. Also, when the breast is markedly engorged, as it is during pregnancy or lactation, FNA is technically more difficult to perform because of the small-caliber needle. Others20 have demonstrated that FNA in the diagnosis of breast lesions in pregnant women can be highly accurate with no false positives. The literature is divided on the utility of FNA in pregnant women with breast masses.

Another minimally invasive option to obtain a pathologic diagnosis in the pregnant women would be a core-needle biopsy of the breast abnormality. Most clinicians are wary of this technique in the postpartum lactating breast because of the possible complication of a milk fistula.21 However, in the pregnant breast, milk fistula formation is not an issue. For nonpregnant women, the literature suggests that image-guided core biopsy has the highest yield for a cancer diagnosis and minimizes false negatives.22 For patients with a high level of suspicion for breast cancer, when the core-needle biopsy does not yield a cancer diagnosis, an incisional or excisional biopsy must be performed to establish the diagnosis.

Decision Making in the Treatment of Gestational Breast Cancer

When pregnant women are diagnosed with breast cancer, it is an extremely complex and overwhelming time for them, their family, and often the medical team treating them. Treatment decisions are best made with the guidance of a multidisciplinary team and include discussions about specific approaches to managing the breast cancer and protecting the fetus during the treatment. It is important to clarify that the goals of treatment do not force a woman to choose between keeping a pregnancy or treating the cancer—both be accomplished safely, in the vast majority of cases, with the thoughtful planning of a multidisciplinary team.

The focus of the treatment portion of this chapter will be on gestational breast cancer, and not those who are diagnosed postpartum. The treatment algorithms for most postpartum breast cancer patients are very similar to those used in nonpregnant women. The surgical management of gestational breast cancer represents a unique challenge, both in the breast and in the axilla. To properly plan a patient’s treatment, 3 fundamental questions need to be answered: (1) How far along is the patient in her pregnancy? (2) What is the estimated radiologic size of the patient’s breast cancer? (3) Is there axillary nodal disease?

Surgery in the Treatment of Gestational Breast Cancer

Surgery during Pregnancy

Accurately calculating weeks of gestation allows the clinicians to avoid any possible, even if theoretical, drug-induced fetal defect, particularly in the first trimester. As will be detailed in the following paragraphs, the currently available evidence suggests that no commonly used anesthetic drug is a teratogen, but one cannot assume that some potential for teratogenicity does not exist. Therefore, surgical procedures during the first trimester should be avoided to allow the initial phase of fetal organogenesis to be completed.

Surgical procedures in the third trimester increase the risk of preterm labor. To avoid this possibility, most obstetricians will try to deliver the baby at 37 weeks, because these babies are classified as term infants.23 Sometimes, a specific patient’s case necessitates delivery before 37 weeks. However, these late preterm infants, those delivered between 34 and 36 6/7 weeks, have a well-documented increase in medical complications than their term counterparts, including temperature instability, hypoglycemia, respiratory distress, jaundice, apnea, seizures, and feeding problems.24

Anesthetic Issues

General anesthesia is necessary for a mastectomy or axillary dissection, and either general anesthesia or heavy conscious sedation is necessary for a partial mastectomy or sentinel node procedure. The surgeon caring for the pregnant breast cancer patient needs to be aware of a few basic principles.

Anesthetic issues in the pregnant patient can be divided into 2 major concerns: teratogenicity of the anesthetic agents and maternal physiologic changes as a result of anesthetic agents.25 The teratogenicity of anesthetic agents, defined as the potential effect in chromosomal damage or in carcinogenesis in the fetus, is minimal. Studies that have specifically evaluated the effects of anesthetic agents on the fetus have concluded that the morbidity to the fetus is primarily from the underlying disease, not from the anesthetic agents.26 In an excellent, comprehensive review article, no anesthetic agents were listed as definitively causative of fetal malformations.27 Paralytics do not cross the placenta. Inhalational and local anesthetics, muscle relaxants, narcotic analgesics, and benzodiazepines have all been shown, with reasonable certainty, to be safe in pregnancy.26-28

Multiple cardiovascular and pulmonary physiologic changes occur in the mother during pregnancy. Both the surgeon and anesthesiologist should be aware of these alterations to prevent fetal hypoxia and hypotension. The cardiovascular system of the pregnant patient is hyperdynamic, with an increased cardiac output and an increased heart rate. Total blood volume increases up to 40%, whereas red blood cell volume rises by approximately 25%. This results in a relative anemia of pregnancy, with a drop in hematocrit by approximately 30%. The enlarging uterus pushes both diaphragms cephalad, causing a decreased functional reserve capacity by approximately 20%. Hyperventilation should be avoided, as maternal respiratory alkalosis is easy to produce because resting CO2 is already reduced to 32 mm Hg. Respiratory alkalosis shifts the oxyhemoglobin dissociation curve to the left and thus may impair transfer of oxygen across the placenta. Umbilical blood flow is also decreased with alkalosis. End-tidal CO2 monitoring may help avoid both over- and underventilation.29 Communication between the anesthesia and surgical teams throughout the preoperative, intraoperative, and recovery room phases is critically important to both the mother and the fetus.

Axillary Procedure during Pregnancy

Historically, the patient’s surgical option during pregnancy has been a complete level I and II axillary dissection as part of a modified radical mastectomy. In a gestational breast cancer patient, knowledge of the regional axilla histologic status may strongly influence the patient’s treatment paradigm. For instance, a patient with histologically proven axillary disease may receive a more aggressive chemotherapy regimen as opposed to a patient with tumor-free axillary nodes. For patients with palpable adenopathy, an image-guided FNA or core biopsy should be performed to establish the histologic axillary nodal status.