Comparison of the eighth version of the American Joint Committee on Cancer manual to the seventh version for colorectal cancer: A retrospective review of our data.

AIM

To analyze the survival trends in colorectal cancer (CRC) based on the different classifications recommended by the seventh and eighth editions of the American Joint Committee on Cancer staging system (AJCC-7 and AJCC-8).

METHODS

The database from our institution was queried to identify patients with pathologically confirmed stage 0-IV CRC diagnosed between 2006 and 2012. Data from 2080 cases were collected and 1090 cases were evaluated through standardized inclusion and exclusion criteria. CRC was staged by AJCC-7 and then restaged by AJCC-8. Five-year disease-free survival (DFS) and overall survival (OS) were compared. SPSS 21.0 software was used for all data. DFS and OS were compared and analyzed by Kaplan-Meier and Log-rank test.

RESULTS

Linear regression and automatic linear regression showed lymph node positive functional equations by tumor-node-metastasis staging from AJCC-7 and tumor-node-metastasis staging from AJCC-8. Neurological invasion, venous infiltration, lymphatic infiltration, and tumor deposition put forward stricter requirements for pathological examination in AJCC-8 compared to AJCC-7. After re-analyzing our cohort with AJCC-8, the percentage of stage IVB cases decreased from 2.8% to 0.8%. As a result 2% of the cases were classified under the new IVC staging. DFS and OS was significantly shorter ( = 0.012) in stage IVC patients compared to stage IVB patients.

CONCLUSION

The addition of stage IVC in AJCC-8 has shown that peritoneal metastasis has a worse prognosis than distant organ metastasis in our institution's CRC cohort. Additional datasets should be analyzed to confirm these findings.