Locoregional and systemic control after total neoadjuvant therapy with short-course radiotherapy for locally advanced rectal cancer: long-term outcomes from the LARCT-US study

BACKGROUND: Total neoadjuvant treatment (TNT) results in more complete responses and less risk of distant metastasis (DM) compared with chemoradiotherapy in locally advanced rectal cancer (LARC). The best schedule and the most suitable patients are unknown. In Sweden, after the closure of the RAPIDO trial, all hospitals in five out of six healthcare regions treated LARC patients with an abbreviated RAPIDO schedule, LARCT-US. Long-term data are reported. METHODS: Between July 2016 and June 2020, LARC patients with at least one high-risk criterion for recurrence according to staging MRI (cT4, cN2, mesorectal fascia involvement 1 year after the start of radiotherapy and 61 patients with a pCR) had excellent outcomes (0% with LRR and 3.7% with DM). CONCLUSION: TNT consisting of 5 × 5 Gy followed by four cycles of CAPOX/six cycles of FOLFOX resulted in excellent locoregional and distant control, despite inclusion of more advanced tumours than previous TNT studies. The low LRR risk in LARCT-US could be explained by more adequate distal resection margins practiced at Swedish centres.