Neo-adjuvant FOLFOXIRI and chemoradiotherapy for high risk (“ugly”) locally advanced rectal cancer.

Despite developments in the multidisciplinary treatment of patients with locally advanced rectal cancer (LARC), such as the introduction of total mesorectal excision (TME) by Heald et al. and the shift from adjuvant to neoadjuvant (chemo)radiotherapy ((C)RT), local and distant recurrence rates remain between 5-10% and 25-40% respectively. Several studies established tumour characteristics with particularly bad prognosis; it was demonstrated that the occurrence of mesorectal fascia involvement (MRF+), grade 4 extramural venous invasion (EMVI), tumour deposits (TD) and enlarged lateral lymph nodes (LLN) lead to high local and distant recurrence rates and decreased survival when compared with LARC without these particularly negative prognostic factors. This type of LARC is described as high risk LARC (hr-LARC). Achieving a resection with clear resection margins (R0) is an important prognostic factor for local (LR) and distant recurrence (DM) as well as survival. With the aim to further reduce the risk of recurrent rectal cancer, to diminish distant metastasis and to improve overall survival for patients with LARC, induction chemotherapy (ICT) became a growing area of research. The addition of ICT has the ability to induce more local tumour downstaging, possibly leading to resectability of previously unresectable tumours, more R0 resections and less extensive surgery. In the case of a complete clinical response, surgery may even be omitted. ICT may also have the potential to eradicate micrometastases. Hence, increased local downstaging and reducing distant metastatic spread may reduce LR and DM rates and improve survival and quality of life. In recent years, the use of ICT was investigated and showed promising results, but little is known about the addition of ICT in patients with high risk LARC. Since these patients have a particularly bad prognosis, both with regard to locoregional and distant failure, a more intensified neoadjuvant treatment with FOLFOXIRI is anticipated to improve short- and long term results.

In our sample size estimation a population proportion of 10% pCR (pathological complete response) was assumed after standard chemoradiotherapy. A pCR/sustained cCR (clinical complete response) rate of 20% (reflecting a 100% increase in pCR/cCR) was predicted for in the study population.

Inclusion: 3 years. Follow-up: 5 years.

All patients are treated with neoadjuvant chemotherapy (FOLFOXIRI; 5-fluorouracil, oxaliplatin, leucovorin, irinotecan) followed by chemoradiotherapy.