Colorectal Cancer, Polyps, and Diverticular Disease

• Audio chapter
  Single-voice audio, listen on the commute.
• ABIM-format MCQs
  5-option vignettes with full wrong-answer teaching.
• Study guide
  Tables, decision trees, primary sources.
• AI tutor
  Chapter-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 range of tests is meant to offer every patient an acceptable option.

• 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 ranges from asymptomatic diverticulosis through uncomplicated and complicated diverticulitis to segmental colitis associated with diverticulosis (SCAD), and its management has changed considerably in the last decade.

Podcast episodes

1. 01

   Colorectal Cancer and Polyps: Screening to Therapy

   This episode follows colorectal neoplasia from screening to treatment. Screening prevents cancer by removing precursors and lowers deaths by finding early cancer, so the first decisions are when to start, which test to use, and what a positive stool test requires. Next come polyps, where histology, size, and number set surveillance, and where serrated lesions are easy to miss. Then a new cancer is tested for mismatch repair, staged, and matched to adjuvant therapy by stage and risk. Metastatic disease is treated by reading the tumor profile in order, with mismatch repair first. The episode ends with rectal cancer, where the pelvis calls for pelvic MRI, total neoadjuvant therapy, and sometimes watch-and-wait.

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2. 02

   Up

   Diverticular disease is a common, usually silent finding that sometimes turns into inflammation, and the episode follows three patients through the decisions that follow. A man with a first attack shows how CT confirms and grades diverticulitis, who can be managed without antibiotics, why colonoscopy follows a first episode, and how to counsel on modifiable risks. His later attacks show why surgery is no longer tied to attack count. A woman with a pelvic abscess shows when to drain, when to operate, and what a colovesical fistula looks like. A third patient has rectum-sparing colitis in a diverticular segment, treated with mesalamine.

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Key topics

• ·Why screening works and when it starts
• ·Screening tests and their limits
• ·Positive stool test with a normal colonoscopy
• ·Family history and earlier screening
• ·Adenomas, serrated lesions, and surveillance
• ·Serrated polyposis syndrome
• ·Mismatch repair testing and Lynch syndrome
• ·TNM staging and adjuvant chemotherapy
• ·Metastatic disease and the tumor profile
• ·Immunotherapy for mismatch repair deficiency
• ·Rectal cancer and watch-and-wait
• ·Diverticula and who gets them
• ·Diagnosing diverticulitis with CT
• ·Hinchey classification
• ·Antibiotics or observation in uncomplicated disease
• ·Colonoscopy after a first attack
• ·Recurrence risk and modifiable factors
• ·Abscess drainage and urgent surgery
• ·Fistulas and strictures
• ·Elective resection criteria
• ·Segmental colitis associated with diverticulosis