[Radiotherapy standard and progress in locally advanced rectal cancer]

Abstract

Recently, treatment strategy optimization for neoadjuvant therapy of rectal cancer includes two aspects: (1) Increasing treatment intensity may improve pathological complete response rate, including increasing radiation dose or concurrent chemotherapy intensity, or shifting adjuvant chemotherapy; (2) Short-course radiotherapy or neoadjuvant chemotherapy which can promise treatment efficacy will decrease toxicity and lead to better tolerance. Long-course chemoradiotherapy is the recent treatment standard for locally advanced rectal cancer. NCCN guidelines do not recommend combined chemotherapy in the radiotherapy period. However, it is important for individualized treatment of rectal cancer if appropriate patients who may benefit from the combined concurrent chemotherapy can be selected. Short-course radiotherapy is defined as 5 Gy × 5. It is recommended for T3 or N+ rectal cancer in NCCN guidelines, but not for T4 patients. In ESMO guidelines, stratified patients of intermediate risk by MRI can be treated with either short-course or long-course radiotherapy, but short-course radiotherapy is not recommended for T4 or positive mesorectum fascia (MRF+) patients with high risk. Neoadjuvant chemotherapy incorporated in the neoadjuvant part has been a therapeutic choice in NCCN guidelines. However, It is still unclear whether chemotherapy upfront as a component of neoadjuvant treatment or even completion of chemotherapy before surgery can improve treatment outcome or not. There are phase II( studies focused on this issue and final results are pending.