Neoadjuvant treatment response as a tumor necrosis grade for patients with rectal cancer.

e14563 Background: Neoadjuvant chemoradiotherapy for rectal cancer results in prevention of local recurrence and may achieve sphincter conserving surgery. Association between pathologic response evaluated after radical tumor resection and patient prognosis was well established. The object of this study was to assess the association between the degree of tumor necrosis after chemoradiotherapy and oncologic outcomes. Methods: In all, 225 patients with locally advanced rectal cancer (stage II and III by endorectal ultrasonography, CT and MRI) had 50.4 Gy over 5.5 weeks, plus 5-fluorouracil and leucovorin and surgery was performed at 7 to 10 weeks after completion of all therapies. Pathologic tissue necrosis after chemoradiotherapy was reviewed and scored as follows: Grade 0, no response; Grade 1, necrosis or disappearance of tumor cells less than 2/3; Grade 2, necrosis or disappearance of tumor cells more than 2/3; and Grade 3, no viable cells (ypCR). Correlation analysis was performed using Pearson’s Chi sq...