{"type":"rich","version":"1.0","provider_name":"Transistor","provider_url":"https://transistor.fm","author_name":"Board Pearls","title":"Chapter 15, Ep 1 of 2: CRC Screening Biology Treatment Polyps","html":"","width":"100%","height":180,"duration":1001,"description":"Episode one of two on the Colorectal Cancer, Polyps, and Diverticular Disease chapter, tracing the neoplastic pathway from average-risk screening through molecular subtyping to stage-based treatment and polyp surveillance. The organizing thread is mechanism: why screening starts at forty-five, why MLH1 loss reflexes to BRAF, and why histology sets the surveillance interval.\n \nTopics covered\n\nAverage-risk CRC screening at 45\nScreening modalities and intervals\nAdenoma-carcinoma vs serrated pathways\nUniversal mismatch-repair reflex testing\nTNM staging and workup\nStage-based and molecular treatment\nRectal cancer and total mesorectal excision\nPost-polypectomy surveillance intervals\n \n \nKey decisions\n\nAverage-risk screening starts at 45, runs to 75, shared decision 76 to 85; FDR with CRC or advanced adenoma starts at 40 or 10 years before youngest case with 5-year intervals.\nA positive stool DNA with a high-quality negative colonoscopy needs no further GI workup; any positive noninvasive test is an indication for diagnostic colonoscopy.\nMLH1 loss reflexes to BRAF or MLH1 methylation testing; MLH1 loss with positive BRAF is sporadic serrated disease with no germline implication, while MSH2, MSH6, or isolated PMS2 loss goes straight to germline testing.\nAt least 12 lymph nodes must be examined for adequate node staging; there is no lower fallback minimum.\nMSI-high stage II tumors do not benefit from single-agent fluorouracil and are usually observed; stage III gets mandatory oxaliplatin-based adjuvant chemotherapy.\nAnti-EGFR therapy is used only in RAS-wild-type left-sided primaries; MSI-high metastatic disease gets first-line pembrolizumab; BRAF-mutant disease gets a BRAF inhibitor plus cetuximab.\nAdvanced adenoma is 10 mm or larger, villous or tubulovillous histology, or high-grade dysplasia, any one sufficient, and gets a 3-year surveillance interval; any proximal hyperplastic polyp 10 mm or larger is managed as a sessile serrated lesion.\n \n \nThis is an AI-generated...","thumbnail_url":"https://img.transistorcdn.com/-FuAdDBcPDLhEoUmroZKtOBRvuBn_FHPpYlh41hOnU4/rs:fill:0:0:1/w:400/h:400/q:60/mb:500000/aHR0cHM6Ly9pbWct/dXBsb2FkLXByb2R1/Y3Rpb24udHJhbnNp/c3Rvci5mbS9iNzlh/ZTU4Y2MzNWExMjQ5/MjA5OWMwMmI3ZTk5/NGFiZS5wbmc.webp","thumbnail_width":300,"thumbnail_height":300}