Prognosis for Colorectal Cancer
The prognosis for colorectal cancer varies significantly by stage, with 5-year survival rates ranging from 93.2% for stage I to 8.1% for stage IV disease, based on comprehensive SEER data analysis of nearly 200,000 patients. 1, 2
Survival Rates by Stage
- Overall 5-year colon cancer-specific survival rate is approximately 65.2% 1, 2
- Stage-specific 5-year survival rates according to AJCC sixth edition staging:
Prognostic Factors
Patient-Related Factors
- Age ≥60 years is associated with poorer survival outcomes 3, 4
- Performance status significantly impacts prognosis, with WHO performance status 3 indicating poor prognosis 3
Tumor-Related Factors
- TNM stage is the most important independent prognostic factor 4, 5
- Histological grade affects survival, with poorly differentiated tumors having worse outcomes 3, 4
- Lymphatic and vascular invasion are negative prognostic indicators 4
- Elevated preoperative carcinoembryonic antigen (CEA) levels (>5 ng/ml) correlate with poorer outcomes 4
Treatment-Related Factors
- Complete surgical resection significantly improves survival 3
- Adjuvant chemotherapy provides approximately 15% absolute survival benefit in stage III disease 1
- Cancer-directed surgery for selected patients with advanced disease can provide sustained survival benefits 6
Important Considerations and Caveats
- The unusual survival pattern between stages IIb and IIIa (where IIIa has better survival than IIb) likely reflects the benefit of adjuvant chemotherapy routinely given to stage III patients but not always to stage II patients 2
- High-risk features in stage II disease that may warrant adjuvant therapy include: T4 tumors, poorly differentiated histology, vascular/lymphatic/perineural invasion, obstruction or perforation at presentation, inadequate lymph node sampling (<12 nodes), and high CEA levels 1
- Conditional survival estimates improve over time for patients who have already survived a period after diagnosis, particularly for those who underwent cancer-directed surgery 6
- Mortality rates for colorectal cancer have been declining in many Western countries due to screening programs, early detection, and more effective therapies 1
Recent Trends and Improvements
- Overall 5-year survival rates have improved from approximately 50% in the 1980s to 56% in the 1990s 5
- Local recurrence rates for rectal cancer have decreased from 10% to 6% between the 1980s and 1990s 5
- Stage III colorectal cancer 5-year survival has improved from 48% to 54% between these decades 5
- Despite overall improvements, there has been a concerning increase in colorectal cancer incidence among patients under 50 years of age 1
Staging and Risk Assessment
- Proper staging is essential for accurate prognostication and treatment planning 1
- Comprehensive staging should include clinical examination, blood counts, liver and renal function tests, CEA measurement, chest imaging, abdominal/pelvic CT, and complete colonoscopy 1
- At least 12 lymph nodes should be examined for accurate staging 1