The impact of rectal cancer tumor height on recurrence rates and metastatic location: A competing risk analysis of a national database.

BACKGROUND: The impact of rectal cancer tumor height on local recurrence and metastatic spread is unknown. The objective was to evaluate the impact of rectal cancer tumor height from the anal verge on metastatic spread and local recurrence patterns.

METHODS: The Norwegian nationwide surgical quality registry was reviewed for curative rectal cancer resections from 1/1/1996-12/15/2006. Cancers were stratified into five height groups: 0-3 cm, >3-5 cm, >5-9 cm, >9-12 cm, 12 cm-HI. Competing risk and proportional hazards models assessed the relationship between tumor height and patterns of metastasis and survival.

RESULTS: 6859 patients were analyzed. After median follow-up of 52 months (IQR 20-96), 26.7% (n = 1835) experienced recurrence. With tumors >12 cm, the risk of liver metastases increased (crude HR 1.49, p = 0.03), while lung metastases decreased (crude HR 0.66, p = 0.03), and risk of death decreased (crude HR 0.81, p = 0.001) The cumulative incidence of pelvic recurrence were highest for the low tumors (p = 0.01). Median time to liver metastases was 14months (IQR 7-24), lung metastases 25months (IQR 13-39), pelvic recurrence 19months (IQR10-32), (p < 0.0001). Time to metastases in liver and lungs were significantly associated with tumor height (p < 0.001) CONCLUSION: There are distinct differences in metastatic recurrence patterns and time to recurrence from different anatomic areas of the rectum. In crude analyses, tumor height impacted metastatic spread to the liver and lungs. However, when adjusting for treatment variables, the hazard of metastatic spread to the liver and lungs are limited. Nevertheless, time to metastases in liver and lungs is significantly impacted by tumor height. Venous drainage of the rectal cancer may be a significant contributor of rectal cancer metastatic spread, but further research is warranted.