Grand Rounds

Treatment of Pregnancy-Associated Breast Cancer

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ABSTRACT

Case Study

KS is a 33-year-old Caucasian married woman who works full time as an accountant and has one daughter who is 2 years old. She enjoys reading and exercising in her spare time. She initially presented in July 2015 at the age of 31 years with a 1-cm breast mass in the left inner breast, which prompted a mammogram to be obtained. The mammogram revealed diffuse and occasionally grouped left breast calcifications. Additionally, there was focal edema at the site of the mass.

A follow-up mammogram was recommended to document stability in 6 months, which demonstrated an interval increase in number and size of segmental pleomorphic calcifications in the lower inner breast spanning 6 cm in size. A stereotactic core needle biopsy was completed and revealed high-grade ductal carcinoma in situ (DCIS) that was estrogen receptor (ER) and progesterone receptor (PR) positive.

Surgical Treatment

KS underwent genetic testing due to her young age at diagnosis of noninvasive breast cancer. She was tested with the breast/ovarian cancer panel, which was negative for mutation.

She preceded to bilateral nipple-sparing mastectomy with left sentinel node biopsy and immediate implant reconstruction in February 2016. The operative pathology revealed 3.3 cm of high-grade DCIS. The surgical margins were negative (less than 1 mm posteriorly and less than 2 mm anteriorly). There was 1 sentinel node and 2 nonsentinel nodes negative for malignancy. The right breast was negative for cancer and both retro areolar margins were negative.

KS did well during the ensuing routine follow-up every 6 to 12 months in surgical oncology at an academic medical center. She was not recommended to take adjuvant endocrine therapy given the benefit of bilateral mastectomy.

In 2017, at a routine oncology follow-up visit, she expressed a desire to have more children. After a negative clinical exam, she and her husband were advised that future contraception may be pursued.

Pregnancy-Associated Breast Cancer Diagnosis

KS was in her usual state of good health when she noticed a left breast mass in the inferior reconstructed breast in June 2017. She presented to the nurse practitioner (NP) in the surgical oncology clinic for evaluation. At that time, she was 17 weeks pregnant and being seen in the same facility for high-risk obstetrics and gynecology care. KS had no other concerning symptoms for recurrent cancer, and her pregnancy had been progressing smoothly.

The surgical oncology NP noted a 1-cm firm superficial mass in the breast at 6 o’clock. She had no other bilateral breast findings or adenopathy. Upon review of systems, she denied new persistent headache, shortness of breath, abdominal pain, weight loss, night sweats, or fatigue.

Due to her pregnancy and the superficial presentation of the breast mass, a left breast ultrasound was ordered. It revealed an 8-mm irregular hypoechoic mass 7 cm from the nipple at the 6 o’clock position in the reconstructed breast.

A diagnostic workup ensued with a left breast ultrasound-guided core needle biopsy. KS was given a diagnosis of clinical stage T1b, N0, grade 2 invasive micropapillary carcinoma: ER positive (Allred 6), PR positive (Allred 8), HER2/neu, immunohistochemistry 3+, and fluorescence in situ hybridization amplified.

After discussion of this recurrent cancer diagnosis, her team opted for a bilateral diagnostic mammogram (with abdominal shielding) and bilateral axillary and breast ultrasound to evaluate the contralateral breast and lymph nodes. There was no adenopathy, a small amount of accessory breast tissue in the right axillary tail region, and a biopsy clip was noted in the left inferior breast at 6 o’clock. The new cancer was not seen on mammogram, likely due to the proximity to the implant.

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