How should early-stage, well-differentiated neuroendocrine neoplasms of the breast with intermediate proliferative index (Ki-67 approximately 20–30%) be managed in the adjuvant setting?

Primary neuroendocrine cancer of the breast is a rare entity and in 2013, WHO classified the neuroendocrine cancers of the breast (NECB) into three subtypes - well-differentiated NE tumors, poorly differentiated small cell carcinoma of the breast, invasive breast cancer with NE differentiation. By definition, these tumors should have at least 50% positivity for synaptophysin and/or chromogranin. Presence of DCIS and lack of other sites of metastatic sites are also essential for making a diagnosi...