Predictive ultrasound factors of lymphatic invasion in rectal cancer: "extra-corporeal" study

Objective: the accuracy of preoperative endorectal ultrasound in the status evaluation of lymph nodes is around 50-70%, with a lack of eco-morphological patterns of clinical use. Since, accurate local staging is of great value in prognosis and decision-making we decided to analyze the referenced eco-morphological parameters in an attempt to find a proper predictive tool of clinical help that could improve the accuracy of rectal ultrasound. Material and method: the resected specimens of 24 patients that were operated on by radical surgery because rectal cancer, without preoperative radiotherapy, were suspended in warm water and ultrasound scanned (360° circular probe with a transducer of 10 MHz). All suspicious nodes were recorded and marked for the definitive histological report. Results: from the 24 specimens, 318 nodes were imaged (210 benign and 100 involved). All ultrasound parameters analyzed were significant but only lobulation, echogenicity and hilar reflection were independent values. An score system was design with the addition of all parameters that showed a sensitivity of 98% and specificity of 99,1%. Conclusions: our study shows that a careful study of ultrasound lymph node images can get a high level of accuracy and better help in tailoring the treatment of any particular case.