Evaluation of the response rate to neoadjuvant chemoradiotherapy in patients with rectal adenocarcinoma: a retrospective long-term study in two terciary reference centers

ABSTRACT

Objectives: To evaluate the complete response (CR) rate and surgeries performed in patients with rectal adenocarcinoma who underwent neoadjuvant therapy (NT) at Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo and at Hospital São Paulo, in Ribeirão Preto, from January 2007 to December 2017. Methods: We evaluated 166 medical records of patients with locally advanced rectal adenocarcinoma (T3, T4 or N+) who underwent NT. The regimen consisted of performing conventional (2D) or conformational (three-dimensional-3D/ radiotherapy with modulated intensity - IMRT) at a dose of 45-50.4Gy associated with capecitabine 1650mg/m2 or 5-fluorouracil (5FU) and leucovorin (LV). The following variables were analyzed gender, age, pretreatment stage, radiotherapy, CR index, local and distant recurrence rates. Surgical treatment and complications were also evaluated. Results: The CR index was 28.3%. Patients treated with 3D/IMRT radiotherapy had a higher rate of CR (36.3% x 4.8%; p < 0.001), higher rates of clinical follow-up (21% x 0%; p < 0.001), lower surgery rates (79% x 100%; p < 0.001), higher rates of transanal resection (37.1% x 9.5%; p = 0.001), lower rates of abdominal rectosigmoidectomy (25.8% x 50%; p = 0.007) and lower rates of abdominoperineal resection of the rectum (16.1% x 40.5%; p = 0.002), when compared to patients treated with 2D radiotherapy. Conclusion Modern radiotherapy techniques such as 3D conformal and IMRT, by offering greater adequacy and precision of treatment, could result in better local control and less toxicity in organs at risk, enabling organ preservation strategies and less invasive approaches in selected cases. (AU)