Background: Although precise preoperative assessment of the extent of local cancer spread is important to determine the appropriate treatment strategy, imaging modalities have not been sufficient. The aim of this study was to establish effective preoperative indices that would predict the degree of local spread in patients with rectal carcinoma.
Methods: In specimens from 437 patients with advanced rectal carcinoma, the submucosal horizontal invasive frontal region was examined histologically with reference to three unfavorable characteristics: 1) tumor "budding", 2) poor differentiation, and 3) vascular invasion. In addition, a transanal submucosal biopsy, which targets the tumor edge, was performed on 85 patients to verify the utility of preoperative evaluation of these parameters.
Results: Multivariate logistic analysis showed that three unfavorable parameters had independent impact on the degree of nodal involvement. These parameters related significantly to the number of lymph nodes involved, the development of extranodal tumor deposits, circumferential surgical margin involvement, and lateral pelvic lymph node metastases. Regarding patients without unfavorable parameters as a standard, the odds ratio of pelvic recurrence was 1.8 (0.9-3.4) in patients with one unfavorable parameter and 5.3 (2.7-10.2) in patients with multiple unfavorable parameters. Based on the transanal biopsy, the submucosal invasive frontal region could be estimated in 73 patients (85.9%). Among these cases, the multiple unfavorable parameters were relevant to an increased risk of extensive local spread. In addition, pelvic recurrence developed in 36% of patients with multiple unfavorable parameters (no-risk patients, 5%; single-risk patients, 13%).
Conclusion: Histology in the submucosal invasive frontal region reflects the extent of local spread and can be evaluated preoperatively by transanal biopsy, which should become a useful tool for therapy selection for patients with advanced rectal carcinoma.
Copyright 2002 American Cancer Society.