ABSTRACT
PURPOSE: To investigate whether endosonography is reliable in making radiation therapy decisions in rectal cancer, with possible downstaging taken into consideration. MATERIALS AND METHODS: Ninety patients (52 men, 38 women; median age, 69 years) with rectal adenocarcinoma underwent endosonography within 2 weeks before surgery and radiation therapy (performed in 54 patients). The tumor invasive edge was used for radiation therapy decision making. RESULTS: The local stage was accurately assessed in 65 patients (39 with and 26 without irradiation). The tumor invasive edge was accurately assessed in 63 patients. Overstaging was present in 19 patients; the tumor had grown almost through the muscularis propria in six. The invasive edge (P = .1) and lymph node status were overstaged more often in the patients with than in the patients without irradiation. Tumor was understaged in eight patients: The invasive edge did not penetrate but there was budding beyond the muscularis propria in five; the invasive edge penetrated the muscularis propria in two. In seven of the eight patients, growth beyond the muscularis propria was smaller than the endosonographic resolution. Three patients with understaged, nonirradiated tumors developed pelvic recurrence. None of the patients with irradiation and none of the 16 patients without irradiation but with correct assessment developed pelvic recurrence. CONCLUSION: Preoperative irradiation decision making on the basis of endosonographic findings is uncertain. Downstaging after preoperative irradiation must be considered.
