Divergent Long-Term Clinical Courses in Two Men With Breast Cancer

This retrospective observational study describes two men with grade 2, estrogen receptor-positive, progesterone receptor-positive, HER2-negative invasive breast carcinoma who were treated within the same regional oncology network and had markedly different longitudinal clinical courses. The study examines clinicopathologic characteristics, local and systemic treatment, imaging, laboratory findings, and long-term outcomes.Case 1 had right-sided breast cancer initially documented as T2N0M0 in 2020 and presented to the National Oncology Center in 2023 with extensive involvement of the breast, nipple-areola complex, skin, and right axillary lymph nodes. Core biopsy showed invasive carcinoma of no special type, grade 2, with ER expression of approximately 90-95%, PR expression of 60-70%, HER2 immunohistochemistry 1+, and Ki-67 of approximately 10-12%. He received several systemic treatment regimens, including taxane- and anthracycline-based chemotherapy and later fulvestrant with ribociclib. Surgery was initially considered infeasible and was later offered after a clinical response but declined. The disease subsequently progressed, with pulmonary, osseous, hepatic, mediastinal, and bilateral axillary metastatic involvement documented during 2025-2026.Case 2 was diagnosed in 2016 with left-sided invasive breast carcinoma of no special type, grade 2. He underwent left mastectomy with axillary tissue removal. Six axillary lymph nodes contained metastatic carcinoma, with pathologic classification pT2N2aMx. The tumor showed ER expression of approximately 80%, PR expression of approximately 75%, HER2 immunohistochemistry 1+, and Ki-67 of approximately 30-35%. He received adjuvant anthracycline/cyclophosphamide-based chemotherapy followed by taxane treatment. At the latest documented assessment on 18 June 2026, approximately 9.6 years after surgery, there was no documented locoregional recurrence, no enlarged regional lymph nodes, no focal hepatic lesion, and serum CA 15-3 remained within the local reference range.The study focuses on the contrast between these two clinical courses despite broadly similar hormone receptor-positive, HER2-negative phenotypes. It evaluates the importance of anatomic stage, nodal burden, local disease control, treatment exposure and continuity, and serial clinical and imaging assessment. The comparison also illustrates that Ki-67, receptor status, or CA 15-3 should not be interpreted in isolation when assessing an individual patient's long-term course