Prognostic factors for disease-free survival in patients with T3-4 or N+ rectal cancer treated with preoperative chemoradiation therapy, surgery, and intraoperative irradiation.

Purpose: Fluoropyrimidine-radiosensitizing agents in conjunction with preoperative radiotherapy have proven to induce tumor and nodal downstaging effects, sphincter preservation promotion, and mid-term favorable survival rates. Intraoperative electron beam radiation therapy may improve pelvic control in patients with locally advanced rectal cancer stages. Potential predictive factors for response and disease-free survival, with intense local multidisciplinary approach, are analyzed.

Methods And Materials: One hundred fifteen patients with rectal cancer were treated with oral 5-fluorouracil or Tegafur with preoperative radiotherapy, surgery, and intraoperative electron beam radiation therapy to identify potential pre- and on-treatment characteristics that might be of prognostic value for disease outcome. Univariate and multivariate analyses were performed.

Results: Older patients and those treated with Tegafur were more likely to achieve a major histologic response, categorized as persistence of minimal residual microscopic disease foci in the surgical specimen ("mic" response). Factors unfavorably associated with disease-free survival in the multivariate model were male gender and persistence of macroscopic disease in the rectal wall ("mac" response). Accordingly, 3-year disease-free survival rates in the groups of patients with 0, 1, or 2 of these risk factors were 100%, 81%, and 53%, respectively (p < 0.001).

Conclusions: Females with an intense pathologic response (pT(mic) residue) to preoperative chemoradiotherapy have an excellent 3-year disease-free survival. This information might be of interest for stratification of patients in the development of adjuvant treatment trials.