Colorectal cancer

Background

• Colorectal cancer is extremely common

Clinical Features

• Asymptomatic, frequently grow slowly for long period of time before symptomatic
• Lower GI bleed (occult or visible BRBPR/hematochezia
• Fatigue, generalized weakness due to anemia
• Change in bowel habits, constipation, tenesmus in rectal cancer
• Obstruction if mass large enough (left colon > right)
  • Abdominal pain
    • Focal pain or Peritonitis if perforation
• Signs/symptoms of metastatic disease (e.g. hepatomegaly, ascites, lymphadenopathy) may be initial presentation

Differential Diagnosis

Lower gastrointestinal bleeding

• Upper GI Bleeding
• Diverticular disease
  • Diverticulosis
  • Diverticulitis
• Vascular ectasia / angiodysplasia
• Inflammatory bowel disease
• Infectious colitis
• Mesenteric Ischemia / ischemic colitis
• Meckel's diverticulum
• Colorectal cancer / polyps
• Hemorrhoids
  • Internal hemorrhoid
  • External hemorrhoid
• Aortoenteric fisulta
• Rectal foreign body
• Rectal ulcer (HIV, Syphilis, STI)
• Anal fissure

LLQ Pain

• Diverticulitis
• Kidney stone
• UTI
• Pyelonephritis
• Ectopic pregnancy
• Infectious colitis
• Inflammatory bowel disease (Crohn's Disease, Ulcerative Colitis)
• Inguinal hernia
• Mesenteric ischemia
• Epiploic appendagitis
• Mittelschmerz
• Ovarian cyst
• Ovarian torsion
• PID
• Psoas abscess
• Testicular torsion
• Appendicitis
• Abdominal aortic aneurysm
• Herpes zoster
• Endometriosis
• Colon cancer
• Irritable bowel syndrome
• Small bowel obstruction

Evaluation

• CBC, LFTs, coags if bleeding or signs of hepatic involvement
• CT abdomen- not definitive but may catch large mass or other alternative diagnoses
• Definitive diagnosis not likely to be made in ED, but suggestion of malignancy may be made on imaging if large mass seen
  • Colonoscopy with biopsy
  • Serum CEA
  • Surgical pathology

Management

• Transfuse pRBCs prn for anemia
• Consult surgery for obstruction or perforation
  • May also help coordinate outpatient diagnostic workup

Disposition

• Discharge if clinically stable

References

https://www.merckmanuals.com/professional/gastrointestinal-disorders/tumors-of-the-gastrointestinal-tract/colorectal-cancer