Efficacy and safety of short duration radiotherapy combined with chemotherapy for advanced rectal cancer.

Background: Radiotherapy or chemoradiotherapy is widely used for the treatment of rectal cancer preoperatively. Although the combination of radiotherapy and chemotherapy as an established preoperative neoadjuvant therapy shows high efficacy in the treatment of rectal cancer, some patients experience a response of poor tolerance and outcomes due to the long duration radiotherapy. The study compared short duration radiotherapy plus chemotherapy long duration radiotherapy plus chemotherapy for rectal cancer to determine whether short duration radiation treatment should be considered to diminish complications, reduce risk of recurrence and improve survival in patients with rectal cancer.

Aim: To evaluate the efficacy and safety of short duration radiotherapy combined with chemotherapy for the treatment of advanced rectal cancer.

Methods: One hundred patients with stage IIIB or higher severe rectal cancer were selected as the study subjects at The First Affiliated Hospital of Hebei North University between December 2018 and December 2019. The patients were assigned to different groups based on the treatment regimens. Fifty patients who received preoperative short durations of radiotherapy plus chemotherapy were enrolled in an observation group and fifty patients who received conventional radiotherapy and chemotherapy were enrolled in a control group. Colonoscopic biopsy was performed for all patients with pathological diagnosis of rectal cancer. The expression of tumor-related factors such as RUNX3 and Ki-67 was quantitatively analyzed using immunohistochemistry in the tissues of the patients before and after treatment. Moreover, the duration of procedure, the amount of bleeding during the operation, the anus-conserving rate, the incidence of postoperative complications (wound infection, anastomotic leakage, postoperative intestinal obstruction, .) and postoperative pathology were compared between the two groups. The overall survival rate, recurrence rate and distant metastasis rate were also compared through postoperative reexamination and regular follow-up.

Results: There was no significant difference in the positive expression rate of RUNX3 and Ki-67 between the two groups before the treatment ( > 0.05). Compared with the pretreatment value, the positive rate of RUNX3 was increased and the positive rate of Ki-67 was decreased in both groups after the treatment (all < 0.05). The incidence of leukopenia, thrombocytopenia, neutropenia and diarrhea were higher in the observation group than in the control group (all < 0.05). There was no significant difference in the incidence of anemia, fatigue, neurotoxicity and nausea and vomiting between the two groups (all > 0.05). No significant difference was observed in the duration of procedure, intraoperative bleeding, the anus-conserving rate and the incidence of postoperative complications between the two groups ( > 0.05). After 1 year of follow-up, the 1-yr survival rate was 80.0% in the observation group and 68.0% in the control group, the recurrence rate was 8.0% in the observation group and 10.0% in the control group, the distant metastasis rate was 6.0% in the observation group and 8.0% in the control group difference (all < 0.05).

Conclusion: Short duration radiotherapy combined with chemotherapy can improve the cure rate, prolong the survival time and reduce the incidence of complications in patients with advanced rectal cancer.