To be or not to be: significance of lymph nodes on pretreatment CT in predicting survival of rectal cancer patients.

PURPOSE

To assess the extent to which pretreatment imaging of lymph nodes by computed tomography (CT) predicts survival of patients with rectal cancer.

MATERIALS AND METHODS

We retrospectively analyzed 70 patients with rectal cancer, who had pretreatment CT and curative surgery between December 1999 and October 2003. These patients were followed until December 2007, ensuring minimal follow-up time of 49 months. Two radiologists who reviewed the CT images on workstations had no prior access to clinical and treatment information regarding the selected patients. The parameters assessed for survival analysis were as follows: patient age, sex, CEA and CA199 level, preoperational therapy, tumor location, serosal invasion, largest diameters and numbers of lymph nodes on pretreatment CT. Kaplan-Meier survival curves, the log-rank test, and the multivariate Cox proportional hazards model were used to evaluate the prognostic value of the parameters.

RESULTS

Using pretreatment CT as prognostic tool, we found that both size and number of lymph nodes correlated with the overall survival of patients with rectal cancer. The data proved that a diameter smaller than 8mm for the largest lymph node was correlated with prolonged survival (P < 0.001). Meanwhile, patients with more than 4 lymph nodes had a significantly worse disease-specific survival (P = 0.042). Both parameters are independent prognostic factors (hazard ratio 4.910 and 3.563) and could predict the overall survival of rectal cancer patients.

CONCLUSION

The lymph node size and number, as determined by pretreatment CT, is an important clinical prognostic factor in patients with rectal cancer. The pretreatment CT findings could be used to predict survival and plan appropriate therapies.