From the Guidelines
Breast cancers with neuroendocrine features are typically ER-positive and PR-positive, with approximately 80-90% being ER-positive and 60-70% being PR-positive, as supported by the most recent guidelines 1. The hormone receptor status of these tumors is crucial in determining their potential response to endocrine therapies.
- The American Society of Clinical Oncology/College of American Pathologists guideline update recommends ER testing of invasive breast cancers by validated immunohistochemistry as the standard for predicting which patients may benefit from endocrine therapy 1.
- The guideline also recommends that breast cancer samples with 1% to 100% of tumor nuclei positive should be interpreted as ER positive, with a new reporting category of ER Low Positive for samples with 1% to 10% of cells staining ER positive 1.
- The strong hormone receptor expression in neuroendocrine breast cancers reflects their cellular differentiation and origin, as neuroendocrine cells often maintain hormone sensitivity.
- This hormone receptor profile has important clinical implications, as it makes these tumors potentially responsive to endocrine therapies such as tamoxifen, aromatase inhibitors, or fulvestrant.
- The high rate of hormone receptor positivity may contribute to the generally better prognosis of well-differentiated neuroendocrine breast cancers compared to poorly differentiated variants.
- Treatment decisions should still be individualized based on the specific tumor characteristics, stage, and patient factors rather than solely on the neuroendocrine features, as recommended by the guidelines 1.
From the Research
Hormone Receptor Status in Breast Cancers with Neuroendocrine Features
- The typical hormone receptor status of breast cancers with neuroendocrine features is usually hormone receptor (HR)-positive and human epidermal growth factor type 2 (HER2)-negative 2.
- These tumors often express estrogen receptor (ER) and progesterone receptor (PR), making hormonal therapy a reasonable treatment option 2, 3.
- Primary neuroendocrine carcinoma (PNEC) of the breast can have high expression of ER and PR, and hormonal therapy has been shown to be effective in treating these tumors 3.
- The majority of breast cancers are positive for ER and depend on estrogens for growth, and other steroid hormone receptors such as PR and androgen receptor (AR) are emerging as additional prospective targets in breast cancer 4.
- Steroid hormone receptors, including ER, PR, and AR, have been evaluated as independent prognostic factors and predictive factors for endocrine manipulation in the clinical management of breast cancer 5.
- Approximately 70-80% of breast cancers express hormone (estrogen or progesterone) receptors, and patients with these hormone-dependent breast malignancies benefit from therapies targeting endocrine pathways 6.