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[Sensitivity study on preoperative individual concomitant radiochemotherapy for rectal cancer].

OBJECTIVE
To explore the predictive factors of sensitivity to preoperative concomitant radiochemotherapy for the local mid-low advanced rectal cancer in order to guide the individualized therapy.


METHODS
Clinicopathologic data of 44 patients with local mid-low advanced rectal cancer receiving preoperational concomitant radiochemotherapy were retrospectively analyzed. Expression of epidemical growth factor receptor (EGFR) in biopsy specimen was detected with SP immunohistochemistry (IHC). Downstaging of tumor TNM stage and tumor regression grade (TRG) after radiochemotherapy were used as the standards of sensitivity to preoperational concomitant radiochemotherapy. Association of EGFR expression and pathological change with clinicopathological data before radiochemotherapy (gender, age, pathological type, tumor TNM stage, serum CEA, CA199, radiation method, etc) was analyzed.


RESULTS
Percentage of downstaging of tumor TNM stage and 3-4 TRG in patients with negative or weak positive EGFR expression was significantly higher as compared to those with strong and moderate positive EGFR expression [86.7% (13/15) vs. 30.4% (7/23), P<0.01; 80.0% (12/15) vs. 8.7% (2/23), P<0.01]. Percentage of downstaging of tumor TNM stage and 3-4 TRG in patients with tubular adenocarcinoma was significantly higher as compared to those with mucous adenocarcinoma [61.8% (21/34) vs. 10.0% (1/10), P<0.01; 47.1 (16/34) vs. 0 (0/10), P<0.01]. EGFR expression was not associated with pathological type (P>0.05). Sensitivity to preoperative concomitant radiochemotherapy was not associated with age, gender, tumor stage, tumor differentiation, serum CEA, serum CA199 and radiation method (all P>0.05).


CONCLUSIONS
Pathological type and EGFR expression level may be two independent predictive markers of sensitivity to preoperative concomitant radiochemotherapy for patients with rectal cancer. Patients with tubular adenocarcinoma or low EGFR expression in tumor tissue may be more sensitive to concomitant radiochemotherapy.