1. TN Categorization for Rectal and Colon Cancers Based on National Survival Outcome Data
LL Gunderson1, JM Jessup 2, DJ Sargent 3,
FL Greene 4, A Stewart 5
for the AJCC Hindgut Taskforce (HTF)
1Mayo Clinic Cancer Center – Arizona; Scottsdale, AZ
2National Cancer Institute, Rockville, MD
3Mayo Clinic Cancer Center – Rochester; Rochester, MN
4Carolinas Medical Center; Charlotte, NC
5American College of Surgeons; Chicago, IL

2. Colorectal Cancer – TN Categorization Background
AJCC 6th Edition: Added outcomes-based substaging
Stage II subdivided: IIA (T3N0M0) and IIB (T4N0M0)
Stage III subdivided: IIIA (T1-2N1), IIIB (T3-4N1), IIIC (TanyN2)
Rectal Pooled Analyses: Outcomes supported revised substaging of Stage III
T1-2N2 cancers - survival and relapse similar to T4N0 (IIB) or T3N1 (IIIA)
T4N1 cancers – survival and relapse similar to T3N2 and T4N2
AJCC Hindgut Taskforce - sought validation in a population-based dataset that depth of invasion interacts with nodal status to affect survival

3. Colorectal CA – Rectal Pooled Analysis Survival and Relapse Rates by Risk for Relapse Category^

4. Colorectal CA – SEER Population-Based Analysis Methods – Patient Group/Tumor Stratification
SEER Population-based data: Jan 1, 1992 to Dec, 2004
Patient Group: Rectal CA – 35,829 patients, Colon CA – 109,953 patients
Tumor Stratification
Extent of disease: T4N0 stratified by
‘Tumor penetrates the surface of visceral peritoneum’ (T4a) vs.
‘Tumor invades or is adherent to adjacent organs or structures’ (T4b)
Number of positive nodes (+ LN)
N1a (1 LN+) vs. N1b (2-3 LN+)
N2a (4-6 LN+) vs. N2b (≥7 LN+)

5. Colon CA – TN Categorization, SEER Analysis Survival Results by TN Category, # LN+, # LN Examined

6. Colon CA – TN Categorization, SEER Analysis Survival Results by TN Category, # LN+, # LN Examined

7. Rectal CA – TN Categorization, SEER Analysis Survival by Expanded TN Category, TNM Stg I-IIIA

8. Rectal CA – TN Categorization, SEER Analysis Survival by Expanded TN Category, TNM Stg IIIB-IIIC

9. Colorectal CA – TN Categorization, SEER Analysis Survival by Expanded TN Category, Rectum vs Colon

10. Colorectal CA – Survival by TN Category, SEER Analyses Proposed Changes – AJCC Staging, 7th Edition

11. Colorectal CA – TN Categorization, SEER Analysis Summary of 5-yr Observed Survival by TN Category
T4a lesions have better prognosis than T4b
Rectal 5-yr Obs Surv: N0, 55.7 vs. 44.7% ; N1, 48.2 vs. 24.3%
Colon 5-yr Obs Surv: N0, 60.6 vs. 45.7% ; N1, 47.0 vs. 27.9%
T1-2N2 lesions have better prognosis than T3-4N2
Rectal 5-yr Obs Surv: 56.1% vs. 37.5% (T3N2) & 26.4% (T4N2)
Colon 5-yr Obs Surv: 61.5% vs. 38.1% (T3N2) & 21.7% (T4N2)
T4bN1 cancers have prognosis more akin to T4N2 than T4aN1
Rectal 5-yr Obs Surv: 24.3 vs (T4N2) vs. 48.2% (T4aN1)
Colon 5-yr Obs Surv: 27.9 vs (T4N2) vs. 47.0% (T4aN1)
Prognosis by nodal status: Related to both number of LN+ and number of LN examined

12. Colorectal CA – TN Categorization, SEER Analysis Conclusions
SEER population-based analyses validates Rectal Pooled Analysis
Supports shift of T1-2N2 lesions from IIIC to IIIA/IIIB
Supports shift of T4bN1 from IIIB to IIIC
SEER outcomes support sub-staging of T4, N1 and N2
T4a has better prognosis than T4b for N0, N1, N2 categories
N1a (1 LN+) has better prognosis than N1b (2-3 LN+)
N2a (4-6 LN+) has better prognosis than N2b (> 7 LN+)
SEER outcomes support revised substaging of Stg II & III
Subdivide current IIB into IIB(T4aN0) or IIC(T4bN0)
Shift more favorable TN2 categories to earlier stages
IIIA – T1N2a
IIIB – T1N2b, T2N2a-b, T3N2a, T4aN2a
Survival Outcomes by TN category
More similar for rectal and colon cancer than expected
Suggest a complex biological interaction between depth of invasion and nodal status