{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T05:10:30Z","timestamp":1779253830439,"version":"3.51.4"},"reference-count":20,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T00:00:00Z","timestamp":1779235200000},"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>Lynch syndrome (LS) is a hereditary cancer predisposition syndrome. Colorectal cancer during pregnancy is extremely rare, and LS-associated cases pose unique diagnostic and therapeutic challenges due to maternal-fetal and genetic considerations.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Case presentation<\/jats:title>\n                    <jats:p>A 37-year-old woman at 22\u00a0+\u00a05 weeks of gestation presented with hematochezia. Ultrasonography and pelvic MRI revealed a 7.2 \u00d7 6.3 \u00d7 6.1\u00a0cm rectal mass with multiple enlarged pelvic lymph nodes posterior to the gravid uterus. Colonoscopy confirmed an ulcerative lesion 10\u00a0cm from the anal verge. Histopathology and immunohistochemistry (MLH1-\/PMS2-\/MSH2+\/MSH6+) confirmed LS-associated rectal adenocarcinoma. Given the poor fetal viability and potential teratogenic effects of systemic therapy, medical termination was performed. The patient subsequently underwent neoadjuvant chemoradiotherapy (50.4 Gy in 28 fractions) combined with two cycles of capecitabine plus oxaliplatin (CapeOx) and tislelizumab, achieving significant tumor regression (yT2N0M0). Laparoscopic Dixon surgery revealed a 2.5 \u00d7 1.5 \u00d7 1.0\u00a0cm ulcerative lesion, corresponding to Tumor Regression Grade (TRG) 1. Six cycles of adjuvant CapeOx with tislelizumab were completed. No severe adverse events occurred, and at 24 months follow-up, the patient remains disease-free.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>LS-associated rectal cancer during pregnancy requires individualized, multidisciplinary management. Medical termination followed by neoadjuvant immunochemoradiotherapy can optimize maternal outcomes while minimizing fetal and genetic risks.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fonc.2026.1813750","type":"journal-article","created":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T04:43:59Z","timestamp":1779252239000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Management of locally advanced lynch syndrome rectal cancer during pregnancy with neoadjuvant immunochemotherapy: a case report"],"prefix":"10.3389","volume":"16","author":[{"given":"Shaoqing","family":"Fan","sequence":"first","affiliation":[{"name":"Department of General Surgery, The Fourth Hospital of Hebei Medical University","place":["Shijiazhuang, Hebei, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiurong","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, The Fourth Hospital of Hebei Medical University","place":["Shijiazhuang, Hebei, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Li","family":"Shi","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, The Fourth Hospital of Hebei Medical University","place":["Shijiazhuang, Hebei, China"]},{"name":"Department of Obstetrics and Gynecology, The Second Hospital of Hebei Medical University","place":["Shijiazhuang, Hebei, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jianan","family":"Dong","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, The Fourth Hospital of Hebei Medical University","place":["Shijiazhuang, Hebei, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2026,5,20]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1001\/jama.2011.743","article-title":"Cancer risks associated with germline mutations in MLH1, MSH2, and MSH6 genes in Lynch syndrome","volume":"305","author":"Bonadona","year":"2011","journal-title":"JAMA"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMra012242","article-title":"Hereditary colorectal cancer","volume":"348","author":"Lynch","year":"2003","journal-title":"N Engl J Med"},{"key":"B3","doi-asserted-by":"publisher","DOI":"10.1097\/MEG.0000000000000863","article-title":"Colorectal cancer diagnosed during pregnancy: systematic review and treatment pathways","volume":"29","author":"Pellino","year":"2017","journal-title":"Eur J Gastroenterol Hepatol"},{"key":"B4","doi-asserted-by":"publisher","DOI":"10.1093\/oncolo\/oyaf097","article-title":"Colorectal cancer in pregnancy: case discussions and real-world data as well as literature review on current knowledge","volume":"30","author":"Poulgrain","year":"2025","journal-title":"Oncologist"},{"key":"B5","doi-asserted-by":"publisher","DOI":"10.1080\/00015458.2018.1493821","article-title":"Management and outcome of colorectal cancer during pregnancy: report of 41 cases","volume":"98","author":"Koci\u00e1n","year":"2019","journal-title":"Acta Obstet Gynecol Scand"},{"key":"B6","doi-asserted-by":"publisher","DOI":"10.3390\/cancers15123202","article-title":"Early-onset colorectal cancer: current insights","volume":"15","author":"Ullah","year":"2023","journal-title":"Cancers (Basel)"},{"key":"B7","doi-asserted-by":"publisher","DOI":"10.1016\/j.bpg.2022.101790","article-title":"Lynch syndrome; 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