Stage III colon cancer: is neoadjuvant chemotherapy ready for prime time?—A narrative review of neoadjuvant chemotherapy for colon cancer

The current standard of care for stage III colon cancer has been adjuvant chemotherapy since this was first shown to be beneficial three decades ago. Despite the improvement in outcomes after introduction of oxaliplatin a decade ago, relapse rates are still significant with associated high morbidity and mortality related to metastatic colon cancer worldwide. Discovery of novel agents for use in colon cancer has been slow and disappointing. Repurposing currently available drugs with known activity in colon cancer into a neoadjuvant chemotherapy regimen has the potential to improve outcomes in colon cancer even while we await development of new drugs. Clinical trials of neoadjuvant chemotherapy for colon cancer to date have been encouraging, demonstrating lower pathologic stage amongst treated patients, and higher rates of R0 resection. However, only early data is available and long term survival outcomes are eagerly awaited. Challenges include optimal staging and patient selection for neoadjuvant therapy, with current methods of radiologic staging lacking specificity to exclude low risk patients (who might not require chemotherapy) from trials. Novel approaches, a notable example being the use of immunotherapy for mismatch repair (MMR) deficient tumours, hold promise of higher response rates without increasing toxicity. Neoadjuvant chemotherapy for this disease still requires further data to be available before it is ready for widespread use, however shows great promise. This review article will discuss the available data regarding rationale and evidence for neoadjuvant chemotherapy for colon cancer.