Polyradiomodification in combined treatment for rectal cancer and the role of therapeutic pathomorphosis

Objective: to evaluate the long-term outcomes of combined treatment with polyradiomodification in patients with rectal cancer depending on the grade of therapeutic pathomorphosis. Materials and methods. The study included 241 patients that received combined treatment with polyradiomodification for T2–3N0–2M0 resectable rectal adenocarcinoma of varying degree of differentiation. All patients received a course of preoperative radiation therapy (5 × 5 Gy) combined with capecitabine and metronidazole (in a polymer composition at a dose of 10 g/m2 per rectum) on days 3 and 5. Some patients additionally underwent local hyperthermia. Four different polyradiomodification regimens were used. We assessed the frequency of relapses, metastases, and relapse-free survival depending on the grade of therapeutic pathomorphosis and cancer stage. Results. Median follow-up time was 48.5 months. One patient with stage III therapeutic pathomorphosis had relapse. Distant metastases were diagnosed in 35 (19.7 %) out of 178 participants with grade 0–II therapeutic pathomorphosis and 4 (6.3 %) out of 63 participants with grade III therapeutic pathomorphosis; the difference between these groups was statistically significant (p = 0.01). No metastases were observed in patients with grade IV therapeutic pathomorphosis. Among patients with T2–3N1–2M0 rectal cancer, the five-year relapse-free survival was higher in the group with grade III–IV therapeutic pathomorphosis compared to the group with grade 0–II pathomorphosis: 95.7 % versus 56.7 % (p = 0.00422). Conclusion. Our treatment strategy ensures good local disease control. Patients with grade III–IV therapeutic pathomorphosis have significantly lower frequency of relapses and metastases and better relapse-free survival.