[Analysis of influencing factors for bidirectional transformation between capillary dilatation and ulcerative types in chronic radiation rectal injury].

Objective: To investigate the differences in clinical characteristics between telangiectatic and ulcerative subtypes of chronic radiation rectal injury, the pattern of subtype transformation during follow-up, and the influencing factors for subtype conversion. Methods: A retrospective case-control study was performed. Clinical and follow-up data of patients diagnosed with chronic radiation rectal injury at the Sixth Affiliated Hospital, Sun Yat-sen University, between March 2008 and December 2024 were collected. Inclusion criteria: (1) history of pelvic radiotherapy; (2) persistent or new-onset rectal symptoms including hematochezia, tenesmus or anal pain occurring at least 3 months after radiotherapy completion; (3) endoscopic findings consistent with typical manifestations of chronic radiation rectal injury, diagnosed as telangiectatic or ulcerative subtype according to the Chinese Multidisciplinary Expert Consensus on Diagnosis and Management of Radiation Rectal Injury (2021 edition); (4) at least two endoscopic records available at our center for the above conditions. Exclusion criteria: (1) prior colorectal resection for primary malignancy; (2) confirmed tumor recurrence or metastasis before the initial endoscopy; (3) concomitant non-radiological intestinal diseases including inflammatory bowel disease, ischemic enteritis, infectious enteritis or drug-induced enteritis. Clinical characteristics, patterns of subtype transformation during follow-up and relevant influencing factors were summarized for enrolled patients. Univariate and multivariate Logistic regression analyses were used to identify predictors of subtype transformation. Odds ratios (OR) with 95% confidence intervals (CI) were calculated. Results: A total of 329 patients were enrolled, including 131 (39.8%) with initial telangiectatic subtype and 198 (60.2%) with ulcerative subtype. Compared with patients with ulcerative subtype, those with telangiectatic subtype had a higher rate of hematochezia [90.8%(119/131) vs. 79.8%(158/198, χ2=7.22, P=0.008], lower hemoglobin level (median 96.00 g/L vs. 104.00 g/L, Z=2.67, P=0.008), and lower white blood cell count (median 4.21×10⁹/L vs. 5.24×10⁹/L, Z=4.75, P<0.001). Patients with ulcerative subtype presented higher Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer (RTOG/EORTC) grades (Z=-6.89, P<0.001), along with higher rates of initial diverting enterostomy [19.8%(26/131) vs. 35.9%(71/198), χ2=9.72, P=0.002], diseased bowel resection [3.8%(5/131) vs. 15.7%(31/198), χ2=11.34, P<0.001] and proportion of argon plasma coagulation (APC) treatment is lower [21.7%(43/198) vs. 36.6%(48/131), χ2=13.63, P=0.004]. The median follow-up time for the entire group of patients was 66 (4-186) months, During follow-up, subtype transformation occurred in 102 patients (31.0%). Progression from telangiectatic to ulcerative subtype was observed in 33.6% (44/131), while reversal from ulcerative to telangiectatic subtype occurred in 29.3% (58/198). Multivariate analysis demonstrated that APC was an independent risk factor for progression from telangiectatic to ulcerative subtype (OR=2.72, 95%CI: 1.25-5.90, P=0.012). A lower Vienna Rectoscopy Score (VRS) was an independent factor associated with reversal from ulcerative to telangiectatic subtype (OR=0.46, 95%CI: 0.31-0.68, P<0.001). Conclusions: Significant differences exist in clinical characteristics between telangiectatic and ulcerative subtypes of chronic radiation rectal injury. Bidirectional transformation between the two subtypes can occur during disease course. APC promotes progression from telangiectatic to ulcerative subtype, and a lower VRS predicts reversal from ulcerative to telangiectatic subtype.