Colorectal Cancer, Polyps, and Diverticular Disease
USPSTF age-45 screening, ADR benchmarks, USMSTF post-polypectomy surveillance intervals, FAP/AFAP/MAP polyposis, Lynch syndrome with universal MMR/IHC, KEYNOTE-177 for MSI-H, the OPRA rectal-cancer pathway, and the Hinchey-graded diverticulitis algorithm with AVOD selective antibiotics.
- Audio chapterSingle-voice audio, listen on the commute.
- ABIM-format MCQs5-option vignettes with full wrong-answer teaching.
- Study guideTables, decision trees, primary sources.
- AI tutorChapter-grounded, answers the question you're stuck on.
What this chapter covers
- Section 15.1: CRC screening modalities and USPSTF age update
Colorectal cancer screening exists because the disease has a long, recognizable precursor lesion and a survivable early stage, and the modality menu is engineered to give every patient a route in.
- Section 15.2: Colorectal cancer epidemiology, molecular subtypes, and staging
Colorectal cancer is the third most common cancer in the United States and the second leading cause of cancer death, with a lifetime risk of about 5 percent in average-risk adults.
- Section 15.3: CRC treatment
Treatment of colorectal cancer is staged surgery in stage I, surgery with selective adjuvant chemotherapy in stage II, surgery with mandatory adjuvant chemotherapy in stage III, and systemic therapy with selective metastasectomy in stage IV.
- Section 15.4: Sporadic polyps and the serrated pathway
Sporadic polyps are the precursor lesions of the conventional and serrated pathways to CRC, and the histologic class drives both the cancer risk and the surveillance interval.
- Section 15.5: Diverticular disease
Diverticular disease is the spectrum from asymptomatic diverticulosis through uncomplicated and complicated diverticulitis to segmental colitis associated with diverticulosis (SCAD), and the boards test it as a management algorithm that has shifted meaningfully in the last decade.
Podcast episodes
- 01
CRC Screening Biology Treatment Polyps
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.
Read the transcript → - 02
Diverticular Disease
Diverticular disease as its own entity, following a management algorithm that shifted meaningfully in the last decade while the boards catch up. Uncomplicated diverticulitis is now an inflammatory process treated with selective rather than reflex antibiotics, and prophylactic resection by episode count is dead. Complicated disease grades on Hinchey and splits at the four-centimeter abscess threshold.
Read the transcript →
Key topics
- Average-risk CRC screening at 45
- Screening modalities and intervals
- Adenoma-carcinoma vs serrated pathways
- Universal mismatch-repair reflex testing
- TNM staging and workup
- Stage-based and molecular treatment
- Rectal cancer and total mesorectal excision
- Post-polypectomy surveillance intervals
- Diverticulosis anatomy and false diverticula
- Acute diverticulitis and CT grading
- Hinchey classification of complicated disease
- Selective antibiotics in uncomplicated disease
- Complicated disease and abscess thresholds
- Recurrence and elective surgery indications
- Segmental colitis (SCAD) as IBD mimic
- Modifiable risk factors and post-episode workup
Sources
Guidelines, consensus statements, and validated instruments this chapter draws on. Named here because the chapter applies them directly.
Professional society guidelines
- American College of Gastroenterology (ACG)
- National Comprehensive Cancer Network (NCCN)