What is the appropriate workup for a suspected case of colorectal (colon and rectal) carcinoma in an adult patient over 50 years old with a possible family history of colorectal cancer?

Workup for Colorectal Carcinoma

All patients with suspected colorectal carcinoma require colonoscopy for diagnosis, followed by comprehensive staging with CT chest and abdomen, plus pelvic MRI for rectal cancers, and measurement of CEA levels. 1

Initial Diagnostic Evaluation

Confirmation of Diagnosis

• Colonoscopy is mandatory to confirm suspected colon or rectal cancer and must visualize the entire colon to identify synchronous lesions 1
• If colonoscopy cannot be completed preoperatively due to obstructing lesion, perform it within 3-6 months postoperatively 1
• Obtain tissue for histological confirmation during colonoscopy 1
• Mark the tumor site during endoscopy for surgical planning 2

Laboratory Assessment

• Complete blood count and platelet count to assess for anemia and baseline hematologic status 1
• Comprehensive metabolic panel including liver function tests 1
• Carcinoembryonic antigen (CEA) level - essential baseline for postoperative surveillance 1

Staging Workup

For Colon Cancer

• CT chest and abdomen for metastatic disease evaluation 1
• MRI or ultrasound of abdomen as alternative imaging 1
• Chest x-ray acceptable if CT chest not performed 1

For Rectal Cancer

• MRI pelvis is critical for local staging and treatment planning 1
• CT chest and abdomen for distant metastases 1
• MRI or ultrasound of abdomen plus chest x-ray as alternatives 1

Family History and Genetic Assessment

Comprehensive Family History

• All colorectal cancer patients must be counseled about family history regardless of age 1
• Document all cancer diagnoses in family members to identify hereditary syndromes 1
• 13% of early-onset colorectal cancer is hereditary 1
• 28% of patients have family history of colorectal cancer 1

Hereditary Syndrome Screening

For patients with ≥10-20 polyps throughout colorectum:

• Screen for Familial Adenomatous Polyposis (FAP) 1
• Perform physical examination for congenital hypertrophy of retinal pigment epithelium (CHRPE), cranial osteomas, or abdominal desmoid tumors 1

For patients with pigmented lesions on oral mucosa, lips, or extremities:

• Screen for Peutz-Jeghers syndrome 1

For all patients ≤70 years old (after excluding FAP and PJS):

• Screen for Lynch syndrome 1
• Use PREMM5 tool to assess likelihood of Lynch syndrome gene pathogenic variant 1
• All early-onset colorectal cancer patients should undergo multigene germline panel testing regardless of risk assessment tool results 1

High-Risk Family History Criteria for Lynch Syndrome

Screen if family has ≥2 histologically confirmed colorectal cancers in first-degree relatives AND any of: 1

• At least one case with multiple colorectal cancers/adenomas
• At least one colorectal cancer before age 50
• At least one Lynch syndrome-related extracolonic malignancy (gastric, endometrial, small intestine, ureteral/renal pelvis, ovarian, hepatobiliary) 1

Pathologic Review Requirements

• Minimum 12 lymph nodes must be examined to properly stage node-negative disease 1
• Patients with <12 nodes examined are suboptimally staged and considered high-risk 1
• Surgeon should mark area of deepest tumor penetration for pathologist evaluation of radial margin 1
• Assess for adverse features: grade 3-4, lymphovascular invasion, positive margins 2

Special Considerations for Symptomatic Patients

High-Risk Symptoms Requiring Immediate Colonoscopy

• Hematochezia (rectal bleeding) 1
• Unexplained iron deficiency anemia 1
• Unexplained weight loss 1
• Fecal immunochemical test (FIT) should NOT be used to triage symptomatic patients with these findings 1

Timing

• Colonoscopy should be performed within 30 days of presentation with alarming symptoms 1
• Delays in obtaining colonoscopy are associated with increased risk of advanced-stage disease 1

Common Pitfalls to Avoid

• Do not use FIT testing in symptomatic patients with high-risk symptoms - proceed directly to colonoscopy 1
• Do not perform inadequate lymph node sampling (<12 nodes) as this leads to understaging 1
• Do not skip family history assessment - this identifies 13% with hereditary syndromes and guides surveillance for relatives 1
• Do not delay colonoscopy in elderly patients over 50 with family history, as they remain at highest risk 1
• For patients under 50, recognize that 72% have NO family history, so young age alone warrants full workup 1