ESTRO 2024 - Abstract Book

S1072

Clinical - Gynaecology

ESTRO 2024

RT4W, RTEND, and 3M for diarrhea, abdominal pain/cramping, proctitis, and fecal urgency. Patients were included if assessments were available at BM, and RT4W or RTEND. To evaluate the impact of EBRT contribution at RT4W, patients were categorized into groups according to lymph-node (LN) boosting and elective irradiation: 1. node negative (N0) with pelvic elective target 2. node positive (N1) with LN boosting of maximum 2 nodes (up to external/internal iliac) and pelvic elective target 3. N1 with LN boosting up to common-iliac and elective pelvic+para-aortic (PAN) target 4. N1 with LN boosting including para-aortic and elective pelvic+PAN target Groups were compared pairwise to assess differences in proportion of patients with toxicity grade 2 or worse (G≥2) using chi-square test(p-value≤0.05). EBRT Body volumes receiving 43Gy and 50Gy (V43Gy and V50Gy) were evaluated for each group. Of 1452 patients enrolled, 1302 fulfilled the criteria for analysis. As shown in Figure1, incidence of GI toxicity was higher at RT4W compared to baseline, followed by a decreasing trend at RTEND. At RT4W, 15.5% patients had G≥2 diarrhea, 6.4% had G≥2 abdominal pain/cramping, 2.4% had G≥2 proctitis, and 25% had fecal urgency (disability to defer for 15 min). The incidence of G≥2 considerably decreased at 3M, being 2.5%, 3.3%, and 0.3% for diarrhea, abdominal pain/cramping and proctitis, respectively. As shown in Figure2, at RT4W the incidence of G≥2 diarrhea was 14.3%, 12.9%, 17.7%, and 25.4% in group 1-4, respectively. Abdominal pain/cramping was 5%, 7.7%, 5.2%, and 14.2% in group 1-4, respectively. Proctitis G≥2 was 2.2%, 1.9%, 2.8%, and 5.6% in group 1-4, respectively. Fecal urgency was 24.4%, 24.1%, 26.5%, and 33% in group 1-4, respectively. The proportion of patients with diarrhea G≥2 was significantly higher in group 4 compared to group 1 (p-value=0.004) and group 2 (p-value=0.003). The proportion of patients with abdominal pain/cramping G≥2 was significantly higher in group 4 compared to group 1 (p-value=0.004) and group 3 (p-value=0.004). The proportion of patients with proctitis G≥2 was significantly higher in group 4 compared to group 1 (p-value=0.047). The proportion of patients with fecal urgency was higher in group 4 compared to group 1, but not reaching statistical significance (p-value=0.062). Overall GI G≥3 toxicity at RT4W was 0.9% (n=5), 2.2% (n=6), 3.2% (n=8) and 3.7% (n=4) in group 1-4, respectively. At 3M, only 3 patients had GI G≥3 toxicity and were in group 3 (1.3%). Median and interquartile range (IQR) for Body V43Gy were 1360 (1212–1541), 1442 (1299–1612), 1734 (1509–1955), and 1849 (1657–2103) cm3 for group 1-4, respectively. Median and IQR for Body V50Gy were 33 (20–51), 75 (43–119), and 137 (92-246) cm3 for group 2–4, respectively. Results:

Conclusion:

Incidence of acute GI toxicity in LACC was highest at RT4W, mainly G1, limited G2, and rare G3. GI toxicity considerably decreased at 3M, with G≥3 comparable to baseline. Proctitis and abdominal pain/cramping G≥2 also returned to pretreatment level. EBRT according to EMBRACE-II protocol was associated with limited GI toxicity at RT4W. GI toxicity was comparable in N0, and N1 (up to two boosted pelvic nodes) patients treated with pelvic elective target. Administration of pelvic+elective PAN in N1 patients (without boosted para-aortic) showed similar or slightly increased GI toxicity compared to N0/N1 with pelvic target. Furthermore, administration of pelvic+PAN elective irradiation combined with para-aortic nodes boosting was associated with higher incidence of GI toxicity, but still tolerable with rare incidence of G≥3 GI (3.7%) and 25% of G≥2 diarrhea at RT4W.