ESTRO 2024 - Abstract Book

S181

Brachytherapy - GI, paediatric, miscellaneous

ESTRO 2024

A total of 251 eligible patients, who received either EBRT (n=103) or CXB (n=148) as their initial treatment with curative intent were included in the study. Patients received a CXB dose of 90-110Gy in 3-4 fractions over 4-6 weeks (each fraction two weeks apart) either before or after EBRT. EBRT was administered either as long-course chemoradiotherapy (45-50Gy/25 #/35 days), long-course radiotherapy alone (45Gy/20#/28days), or short-course radiotherapy (25Gy/5#/5 days). Following treatment, a watch-and-wait policy was adopted for patients who achieved a clinical complete/near response. The median follow-up was 37 [IQR:18-56] months for the EBRT-first group and 32 [IQR:16-54] months for the CXB-first group. In the unadjusted analysis, a higher risk of grade-1(26%) and grade-2(6%) rectal bleeding (p=0.008) was observed in patients who started with CXB, but no significant differences in any of the survival parameters were found. Analysis using the adjusted, propensity matching, and IPTW models, demonstrated a significant improvement of OS (p=0.04, HR (95%CI): 0.69 (0.48-0.98) and a higher risk of grade 1-2 rectal bleeding (p=0.01, OR (95%CI): 2.35(1.16-4.76) in those patients who had been received CXB as their initial treatment (Figure 2). However, DFS (p=0.87), local regrowth rate (p=0.70), and organ preservation rate (p=0.80) were not significantly different between the two groups.

Conclusion:

Small rectal cancer (≤3cm), commencing treatment with CXB, as opposed to EBRT, was associated with improved overall survival, despite an increased risk of grade 1 and 2 rectal bleeding. However, there was no statistically significant improvement in terms of disease-free survival, local regrowth rate, or organ preservation rate with this treatment strategy.

Keywords: Contact X-ray Brachytherapy, propensity score

References:

1.

Papillon J. Present status of radiation therapy in the conservative management of rectal cancer.

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