Mesorectal radiotherapy for early stage rectal cancer: A novel target volume

Abstract

With the introduction of population-based bowel cancer screening, rectal cancer is diagnosed at earlier stages, yet standard treatment still requires the same extensive surgery that is used for more advanced stages. Organ preserving treatment is rapidly developing and is subject of investigation in numerous clinical trials. The STAR-TREC trial is an international, multi-centre randomised trial investigating organ preservation using (chemo)radiotherapy. Patients with small mrT1-3bN0V0M0 tumours are randomized between three arms: standard TME, organ preservation with SCRT or with CRT. In this trial, the clinical target volume has been tailored to the early staged disease of the included patients. This mesorectal irradiation volume includes the mesorectum and pre-sacral lymph nodes at the level of the tumour, two centimetres below and cranially up to the S2-3 interspace level. In contrast to conventional irradiation volumes, the lateral lymph nodes and the nodes along the superior rectal artery are excluded. As a result, the dose to the bowel, bladder, anal sphincter and the neurovascular plexus in the lower pelvis is substantially decreased, especially when combined with modern irradiation techniques, such as dynamic arc therapy. These lower doses are expected to lead to decreasing acute and late toxicity and beneficial functional outcomes. The implementation of this novel target volume will be accompanied by an extensive quality assurance program in the STAR-TREC trial. We describe the rationale behind the novel, mesorectal only radiotherapy treatment used in the STAR-TREC trial specifically tailored for early stage disease, with the goal of organ preservation.

Local Excision ± Chemoradiotherapy vs. Total Mesorectal Excision for Early Rectal Cancer: Case-Matched Analysis of Long-Term Results

“…However, because of a relatively small number of cases, we could not show the benefit of surgery in T2 cancers. Moreover, a group of experts from the STAR-TREC trial proposed limited irradiation volume for early rectal cancer to reduce toxicity and pelvic organ dysfunction ( 32 , 33 ). However, this is the only theoretical proposal and the results of this trial should be awaited.…”

Lateral Lymph Nodes in Rectal Cancer: Do we all Think the Same? A Review of Multidisciplinary Obstacles and Treatment Recommendations

“…Several studies used information about the location of recurrence and/or lymphatic spread for delineation guidelines concerning the rectal tumor, mesorectum and various nodal compartments (4,43). Some authors advise to adapt the CTV based on specific T-or N-stage, resulting in smaller target volumes for selected patients (44)(45)(46). In an attempt to decrease heterogeneity, Valentini et al (42) established international guidelines for the delineation of the elective nodal compartments.…”

Wytyczne postępowania diagnostyczno-terapeutycznego u chorych na raka odbytnicy (C20)

“…If the decision is taken not to use chemotherapy because of fear of its toxicity it is possible to use a fractionated dose of 2.5 Gy and a total dose of up to 40 Gy or a fractionated dose of 3 Gy and a total dose of up to 39 Gy. In patients with cancer of grade cT2 the area of elective irradiation should be smaller than used in advanced cancers [51,52]. Then on the area of only GTV plus the margin, the dose is increased to 60-68 Gy, depending on the location of the tumour in relation to the small intestine.…”