External validation of a rectal cancer outcome prediction model with a cohort of patients treated with preoperative radiochemotherapy and deep regional hyperthermia.

PURPOSE

To validate a nomogram for the prediction of treatment outcomes after preoperative radiochemotherapy and surgery for locally advanced rectal cancer with a cohort of patients treated with additional deep regional hyperthermia.

PATIENTS AND METHODS

A total of 86 patients were treated with preoperative radiochemotherapy and deep regional hyperthermia at our institution. For every patient, the 5-year probability for death, distant metastases and local failure based on a previously published nomogram were calculated and patients were divided into three risk groups.

RESULTS

Low-lying and clinically lymph node positive tumours were more frequent in the validation cohort. Five-year Kaplan-Meier estimates for overall survival (OS), distant metastases-free survival (DMFS) and local control (LC) were 87.3%, 79.9%, 95.8% (observed) and 75.5%, 71%, 90% (predicted), respectively. Discrimination between low- and high-risk groups was at a significant level for all endpoints. The c-index was 0.81 (OS), 0.67 (DMFS) and 0.92 (LC), respectively.

CONCLUSIONS

The nomogram showed reasonable performance when deep regional hyperthermia is incorporated into preoperative therapy. The higher than predicted rates seen for OS and DMFS in particular in the high-risk groups warrant further prospective validation and subsequent investigation of the underlying mechanisms.