{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T05:08:46Z","timestamp":1788930526910,"version":"build-2803163510"},"reference-count":36,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T00:00:00Z","timestamp":1788912000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Invasive lobular carcinoma (ILC) with signet-ring-cell (SRC) differentiation of the breast is a relatively rare disease and is reported to frequently metastasize to the gastrointestinal and urinary systems.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Case presentation<\/jats:title>\n                    <jats:p>\n                      A 66-year-old woman presented for routine breast cancer screening without any subjective symptoms. A mass detected in the upper-outer region of her right breast. Core needle biopsy led to the diagnosis of ILC with SRC of the breast. Positron emission tomography-computed tomography, urine cytology, and upper and lower gastrointestinal endoscopy revealed no abnormal findings, and the disease was diagnosed as cT1cN0M0, Stage I. Immunohistochemical examination showed estrogen receptor (ER)-positive (10%, weak), progesterone receptor (PgR)-negative (0%), human-epidermal growth factor receptor 2 (HER2) score 0, and Ki-67 index of 9.8%, suggesting a luminal B-like subtype. The patient received 4 cycles of epirubicine and cyclophosphamide followed by 4 cycles of docetaxel (DTX) as neoadjuvant chemotherapy (NAC). Because prolonged neutropenia occurred during DTX treatment, temporary treatment interruptions were required; however, all cycles were completed with a relative dose intensity of 80%. As stable disease after completion of NAC, right breast-conserving surgery with sentinel lymph node biopsy was performed. Pathological assessment after neoadjuvant chemotherapy revealed ypT1c (1.8\u00a0cm) sN0 (0\/1), therapeuthic effect Grade 2b, ER- (0%), PgR- (0%), HER2 0, Ki-67 20% of residual tumor remaining in the breast. Therefore, BRACAnalysis\n                      <jats:sup>\u00ae<\/jats:sup>\n                      testing was performed as a companion diagnostic test and was negative. The patient subsequently have received postoperative radiotherapy, and 8 cycles of capecitabine therapy.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>In our cohort of ILC patients treated at our institution, we also observed cases with gastrointestinal metastases; therefore, attention should be paid to symptoms and findings suggestive of metastasis to these sites as well.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fonc.2026.1926146","type":"journal-article","created":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T04:41:54Z","timestamp":1788928914000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["A case of invasive lobular carcinoma with signet-ring-cell differentiation treated with multidisciplinary therapy: a rare case 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