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Breast cancer is the most common tumor type and second only to lung cancer as a cause of cancer death in women. Nearly 300,000 women (and 2800 men) will receive a new diagnosis of breast cancer in the United States in 2023. Despite improvements in treatment options, breast cancer still will lead to 43,700 deaths among women this year.
Breast tumors generally are either ductal or lobular in origin. Ductal carcinomas arise in the lining of the milk ducts and are the most commonly found tumor type in breast cancer. Almost 3 in 4 diagnosed breast cancers histologically are invasive ductal carcinomas, which have spread from the source into surrounding structures. It has no specific histologic indicators and is differentiated from ductal carcinoma in situ by its having spread outside the duct. The presence of lymph node involvement in this patient also confirms invasive ductal carcinoma without metastatic spread. Invasive lobular carcinomas occur much less frequently and have a different histologic appearance of smaller cells that appear to be arranged in linear groups.
Mammography involves low-dose radiation and is used in diagnosis and is the most widely used screening technique for breast cancer. As a screening tool, mammography may detect lesions 1-2 years before they become palpable on breast self-examination. While the incidence of breast cancer in women has slowly increased over the past 20 years, mortality has decreased largely as a result of improved awareness and uptake of screening mammography. Current American Cancer Society guidelines recommend continued mammography screenings at least every other year after age 55 and continued for as long as a woman has a life expectancy > 10 years. Screening or diagnosis using MRI is usually reserved for individuals at high risk for breast cancer or a history of breast cancer before age 50.
For all newly diagnosed primary invasive breast cancers, biomarker testing for estrogen and progesterone receptor expression and HER2 expression are part of the standard workup recommended by the American Society of Clinical Oncology (ASCO) and the National Comprehensive Cancer Network (NCCN) to help guide treatment decisions. Biomarker testing showed that her tumor was ER+ and HER2-negative, the most common finding in breast cancer. The patient's history did not suggest a risk for BRCA or other familial cancer mutations, but molecular testing was done and was negative for BRCA1 and BRCA2. In postmenopausal women, ASCO and NCCN also recommend use of risk assessment tools, such as Oncotype DX, to determine whether chemotherapy will add benefit to systemic endocrine therapy. Postmenopausal patients with ER+/HER2-negative breast cancer, one to three positive nodes, and a score < 26 on the 21-gene Oncotype DX can safely forego cytotoxic chemotherapy and derive maximum survival benefit from hormonal therapy alone.
This patient was diagnosed with a primary tumor of approximately 25 mm, metastasis to two ipsilateral nodes, and no distant metastasis, or stage IIIA. Her risk recurrence score was 20, indicating that she could safely forego the rigors of cytotoxic chemotherapy. She underwent localized breast-conserving surgery and began adjuvant tamoxifen therapy (x 2 years) to be followed with an aromatase inhibitor (x 3 years).
Karl J. D'Silva, MD, Clinical Assistant Professor, Department of Medicine, Tufts University School of Medicine, Boston; Medical Director, Department of Oncology and Hematology, Lahey Hospital and Medical Center, Peabody, Massachusetts.
Karl J. D'Silva, MD, has disclosed no relevant financial relationships.
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