Tumor downstaging and therapeutic pathomorphosis in rectal cancer patients receiving combination therapy with various polyradiomodification regimens

Objective: to evaluate therapeutic pathomorphosis and Tand N-downstaging in response to various polyradiomodification regimens used in the combination therapy for rectal cancer.

Materials and methods. A total of 241 patients received combination therapy for rectal cancer using 4 different polyradiomodification regimens. We assessed therapeutic pathomorphosis and tumor downstaging in these patients. Eighty-two participants (34 %) underwent polyradiomodification with a 14-day course of capecitabine (Cap) given in a therapeutic dose (2 g/m2body surface) (Cap14 + metronidazole (MZ) and Cap14 + MZ + microwave hyperthermia (MW-HT)), whereas the remaining 159 participants (66 %) underwent polyradiomodification with a 5-day course of Cap in a radiosensitizing dose (1.5 g/m2 body surface) (Cap5 + MZ and Cap5 + MZ + MW-HT).

Results. Grade IV therapeutic pathomorphosis was observed in 19.5 % of patients treated with a 14-day course of Cap (Cap14 + MZ and Cap14 + MZ + MW-HT) and 1.3 % of patients treated with a 5-day course of Cap (Cap5 + MZ and Cap5 + MZ + MW-HT) (p = 0.00001). Patients receiving a 14-day course of Cap demonstrated T-downstaging significantly more often than those receiving a 5-day course (41.5 % compared to 9.4 % respectively, p = 0,00001). Regression of regional lymph node metastases was diagnosed in 51.1 % of patients from the Cap14 group only.

Conclusion. Our findings suggest that grade III–IV therapeutic pathomorphosis and tumor downstaging are more frequently achieved in polyradiomodification regimens with a 14-day course of Cap at a dose of 2 g/m2 (Cap14 + MZ and Cap14 + MZ + MW-HT).

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