Contact X-ray brachytherapy boost bolsters 3-year organ preservation rate in rectal cancer
Chemoradiotherapy with a contact X-ray brachytherapy boost significantly increased clinical complete response and 3-year organ preservation rates in patients with early cT2-cT3 rectal adenocarcinoma, particularly tumors smaller than 3 cm.
“The standard of care for rectal cT2 to cT3 adenocarcinoma is radical proctectomy by total mesorectal excision, sometimes preceded by neoadjuvant chemoradiotherapy, external beam radiotherapy or total neoadjuvant treatment,” Jean-Pierre Gerard, MD, of the Antoine Lacassagne Center at Côte d’Azur University in France, and colleagues wrote in The Lancet Gastroenterology & Hepatology. “To enhance quality of life, interest in organ preservation is growing, with a watch and wait approach after neoadjuvant chemoradiotherapy in cases of clinical complete response to neoadjuvant treatment.”
They continued: “An alternative for organ preservation uses contact X-ray brachytherapy, delivering a higher radiation dose through an endocavitary approach.”
In the multicenter, open-label, phase 3 OPERA trial, Gerard and colleagues enrolled 141 adult patients (median age, 69 years; 62% men) with cT2, cT3a or cT3b adenocarcinoma of low-mid rectum, less than 5 cm in diameter. Patients received neoadjuvant chemoradiotherapy and 45 Gy external beam radiotherapy over 5 weeks with concurrent oral capecitabine twice daily (825 mg/m²).
To investigate organ preservation rate at 3 years, 69 patients received a boost of external beam radiotherapy at 9 Gy (group A) and 73 patients received a boost with contact X-ray brachytherapy at 90 Gy (group B). Twenty-nine patients in group A and 32 patients in group B had tumors less than 3 cm in diameter.
After a median follow-up of 38.2 months, the 3-year organ preservation rate was 59% (95% CI, 48-72) in group A and 81% (95% CI, 72-91) in group B (HR = 0.36; 95% CI, 0.19-0.7). In patients with a tumor diameter less than 3 cm, organ preservation rates at 3 years were 63% (95% CI, 47-84) and 97% (95% CI, 91-100), respectively (HR = 0.07; 95% CI, 0.01-0.57). Organ preservation rates were 55% (95% CI, 41-74) and 68% (95% CI, 54-85), respectively, in those with a tumor diameter of 3 cm or more (HR = .54; 95% CI, 0.26-1.1).
Early grade 2 to 3 adverse events occurred in 30% of patients in group A vs. 42% in group B, and the main late side effect was grade 1 to 2 rectal bleeding due to telangiectasia (12% vs. 63%), which subsided after 3 years.
“Organ preservation is a promising new frontier in the management of rectal cancer and could be planned for select tumors using dose escalation with contact X-ray brachytherapy,” Gerard and colleagues wrote. “Although surgery remains the standard of care, tailored organ preservation strategies could be discussed and offered to well-informed patients who wish to avoid radical surgery, mainly when presenting with cT2, cT3a or cT3b tumors of less than 3 cm in size.”
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