Rectal Cancer: Neoadjuvant Therapy
Neoadjuvant therapy is a critical component of the multidisciplinary treatment of patients with rectal cancer. The objective of neoadjuvant therapy, either radiotherapy, combined chemoradiotherapy, or chemotherapy alone, is to reduce the risk of local recurrence in patients with locally advanced rectal cancer undergoing surgical resection. But neoadjuvant therapy provides other potential advantages to rectal cancer patients. It allows early assessment of tumor responsiveness to therapy, which is closely correlated with long-term oncologic outcomes. In addition, neoadjuvant therapy could potentially enable the consideration of organ preservation by allowing for more effective local excision and nonoperative management strategies. Finally, delivering systemic chemotherapy before surgery in patients at risk for distant metastasis has the potential to improve survival by addressing micrometastatic disease earlier and improving treatment compliance. Maximizing neoadjuvant treatment response can therefore have a profound effect on both oncologic and quality-of-life outcomes. In this chapter, we will focus primarily on neoadjuvant therapy for locally advanced rectal cancer (LARC), widely accepted to be clinical stage II (cT3–T4, cN0) or stage III (any cT, cN1–N2) invasive adenocarcinomas of the rectum. We will review various treatment paradigms and the data supporting each.