Analysis of stage and clinical/prognostic factors for colon and rectal cancer from SEER registries: AJCC and collaborative stage data collection system.

BACKGROUND

The Collaborative Stage (CS) Data Collection System enables multiple cancer registration programs to document anatomic and molecular pathology features that contribute to the Tumor (T), Node (N), Metastasis (M) - TNM - system of the American Joint Committee on Cancer (AJCC). This article highlights changes in CS for colon and rectal carcinomas as TNM moved from the AJCC 6th to the 7th editions.

METHODS

Data from 18 Surveillance, Epidemiology, and End Results (SEER) population-based registries were analyzed for the years 2004-2010, which included 191,361colon and 73,341 rectal carcinomas.

RESULTS

Overall, the incidence of colon and rectal cancers declined, with the greatest decrease in stage 0. The AJCC's 7th edition introduction of changes in the subcategorization of T4, N1, and N2 caused shifting within stage groups in 25,577 colon and 10,150 rectal cancers diagnosed in 2010. Several site-specific factors (SSFs) introduced in the 7th edition had interesting findings: 1) approximately 10% of colon and rectal cancers had tumor deposits - about 30%-40% occurred without lymph node metastases, which resulted in 2.5% of colon and 3.3% of rectal cases becoming N1c (stage III A/B) in the AJCC 7th edition; 2) 10% of colon and 12% of rectal cases had circumferential radial margins <1 mm; 3) about 46% of colorectal cases did not have a carcinoembryonic antigen (CEA) testing or documented CEA information; and 4) about 10% of colorectal cases had perineural invasion.

CONCLUSIONS

Adoption of the AJCC 7th edition by the SEER program provides an assessment tool for staging and SSFs on clinical outcomes. This evidence can be used for education and improved treatment for colorectal carcinomas.