Breast Cancer Diagnosed During Pregnancy

Background: Pregnancy-associated breast cancers are cancers diagnosed during pregnancy or within 1 year of delivery. It is rare, occurring in 2.5-7.5/100,000, but these numbers continue to rise as maternal age increases. As a result, prospective studies evaluating diagnosis and treatment are limited. Case Description: Patient is a P1G0 35 yo woman who presented with a new breast mass at 26 wga. Diagnostic workup including core biopsy revealed invasive ductal carcinoma, ER 70%, PR 40%, her-2 negative. After multidisciplinary discussion with the breast team and the patient’s obstetrician, the patient underwent mastectomy with sentinel node biopsy at 28 wga. Pathology showed a 1.9 cm tumor with 5 negative sentinel nodes. Genomic evaluation of her tumor using 21-gene recurrence score revealed significant risk of distant recurrence without chemotherapy. Patient will initiate chemotherapy after delivery. Conclusion: The treatment regimen should be as close to standard of care as possible for a non-pregnant woman with the same cancer. Diagnostic workup should include ultrasound and possible mammogram with shielding of the fetus. Core biopsy can provide definitive diagnosis. Surgery is the mainstay of treatment during pregnancy, and decisions regarding breast conservation are dependent on gestational age at presentation. Adjuvant treatments can be performed with modifications and avoidance of radiotherapy during pregnancy. Decisions regarding treatment require multidisciplinary input between the oncology and obstetric teams to provide effective care with minimal toxicity to the fetus. Clinical Significance: Physiological changes of the breast during pregnancy make diagnosis of new breast cancer difficult. Furthermore, lack of diagnostic suspicion delays diagnosis. Further research is needed to determine the best diagnostic and therapeutic methods to ensure the best prognosis for mother and baby as the prevalence of breast cancer during pregnancy continues to rise