Measurement of the distance between tumor micro-foci and gross tumor in rectal cancer pathological specimens: implication on margin distance of clinical target volume treated with high-dose radiotherapy for rectal cancer.

The micro-foci distances of 95% of rectal adenocarcinoma patients examined were within 6.44 mm peripherally, 5.54 mm inferiorly, and 5.42 mm superiorly. These findings provide reference to set the boost radiotherapy CTV margin for rectal cancer.