A systematic review and meta-analysis of pT2 rectal cancer spread and recurrence pattern: Implications for target design in radiation therapy for organ preservation

Which tumour factors preclude organ preservation in patients with rectal cancer?

BACKGROUND

cT3cdT4, cN2, mesorectal nodes > 8 mm, clinically positive lateral nodes, extramural vascular invasion (EMVI) and mesorectal fascia threatening (MRF+) have been utilized as exclusion criteria in several studies on the watch-and-wait (w&w) strategy. Here, our aim was to validate these criteria through a post hoc analysis of two pooled prospective studies on w&w following routine radio(chemo)therapy.

METHODS

A review of baseline magnetic resonance imaging was performed in a subgroup of 223 patients treated at a single institution. Of these, 17.9 % started w&w, 12.6 % achieved clinical complete response (cCR) and 9.0 % sustained cCR during median follow-up of 54 months.

RESULTS

The multivariable logistic analysis showed that the proportion of circumferential bowel involvement and EMVI significantly influenced the chance of sustained cCR; odds ratios were 0.063 (95 % confidence interval [CI] 0.008-0.489, p = 0.008), and 0.109 (95 % CI 0.014-0.850, p = 0.034), respectively. Sustained cCR was observed in none of the 57 patients with 90 %-100 % circumferential bowel involvement and in only one of the 89 patients with EMVI. In contrast, cT3cdT4, cN2, mesorectal nodes > 8 mm, clinically positive lateral nodes or MRF+ were not independently associated with sustained cCR. Among the subgroups of patients with these features but without (near-)circular tumour or EMVI+, sustained cCR was observed in 12 %-25 % of patients.

CONCLUSION

Sustained cCR after routine preoperative radio(chemo)therapy is unlikely in patients with (near-)circular tumour or EMVI, whereas patients with cT3cdT4, cN2, mesorectal nodes > 8 mm, clinically positive lateral nodes and MRF+ should not be denied w&w.

Required distal mesorectal resection margin in partial mesorectal excision: a systematic review on distal mesorectal spread

BACKGROUND

The required distal margin in partial mesorectal excision (PME) is controversial. The aim of this systematic review was to determine incidence and distance of distal mesorectal spread (DMS).

METHODS

A systematic search was performed using PubMed, Embase and Google Scholar databases. Articles eligible for inclusion were studies reporting on the presence of distal mesorectal spread in patients with rectal cancer who underwent radical resection.

RESULTS

Out of 2493 articles, 22 studies with a total of 1921 patients were included, of whom 340 underwent long-course neoadjuvant chemoradiotherapy (CRT). DMS was reported in 207 of 1921 (10.8%) specimens (1.2% in CRT group and 12.8% in non-CRT group), with specified distance of DMS relative to the tumor in 84 (40.6%) of the cases. Mean and median DMS were 20.2 and 20.0 mm, respectively. Distal margins of 40 mm and 30 mm would result in 10% and 32% residual tumor, respectively, which translates into 1% and 4% overall residual cancer risk given 11% incidence of DMS. The maximum reported DMS was 50 mm in 1 of 84 cases. In subgroup analysis, for T3, the mean DMS was 18.8 mm (range 8-40 mm) and 27.2 mm (range 10-40 mm) for T4 rectal cancer.

CONCLUSIONS

DMS occurred in 11% of cases, with a maximum of 50 mm in less than 1% of the DMS cases. For PME, substantial overtreatment is present if a distal margin of 5 cm is routinely utilized. Prospective studies evaluating more limited margins based on high-quality preoperative magnetic resonance imaging and pathological assessment are required.

Long-Term Results of a Prospective Phase 2 Study on Volume De-Escalation in Neoadjuvant Chemoradiotherapy of Rectal Cancer

PURPOSE

In the current study, we evaluated whether neoadjuvant chemoradiotherapy with reduced treatment volumes due to the exclusion of elective pelvic nodal irradiation is a feasible strategy for selected patients with locally advanced rectal cancer.

METHODS AND MATERIALS

Patients with T2 low-lying/T3, N0-N1 rectal lesions without evidence of disease in the lateral lymph nodes were prospectively recruited. All patients underwent pretreatment testing, including computed tomography imaging of the chest, abdomen, and pelvis with intravenous contrast, pelvic magnetic resonance imaging with intravenous contrast, and 18-fluorodeoxyglucose positron emission/computed tomography. The clinical target volume included the primary tumor and the mesorectum with vascular supply containing the perirectal and presacral nodes, with the upper border at the S2/S3 interspace. The total radiation dose was 50.4 Gy, and fluoropyrimidine-based chemotherapy was associated concomitantly. The primary endpoint of the study was the reduction of gastrointestinal (GI) toxicity, and the secondary endpoints were pathologic complete response, local control, overall survival, and disease-free survival.

RESULTS

Fifty-two patients (30 men, 22 women) with a median age of 67 years (range, 45-85 years) were enrolled in the study. Acute grade 3 GI toxicity was 7.6%, and there were no cases of grade 4 toxicity. Three patients (5.7%) developed a local recurrence. No relapse occurred in the lateral lymph nodes. The local control rate at 5 years was 96.1%. With a median follow-up time of 72.9 months (range, 2.5-127.6 months), the 3- and 5-year overall survival rates were 89.4% and 87%, respectively. The 3- and 5-year disease-free survival rates were 82.4% and 82.4%, respectively.

CONCLUSIONS

De-escalation of radiation therapy target volume reduces GI side effects without compromising efficacy in patients with rectal cancer. These results cannot be clearly extended to high-risk disease and need further evaluation in future randomized trials.

Radiation Therapy for Rectal Cancer: Executive Summary of an ASTRO Clinical Practice Guideline

PURPOSE

This guideline reviews the evidence and provides recommendations for the indications and appropriate technique and dose of neoadjuvant radiation therapy (RT) in the treatment of localized rectal cancer.

METHODS

The American Society for Radiation Oncology convened a task force to address 4 key questions focused on the use of RT in preoperative management of operable rectal cancer. These questions included the indications for neoadjuvant RT, identification of appropriate neoadjuvant regimens, indications for consideration of a nonoperative or local excision approach after chemoradiation, and appropriate treatment volumes and techniques. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

Neoadjuvant RT is recommended for patients with stage II-III rectal cancer, with either conventional fractionation with concurrent 5-FU or capecitabine or short-course RT. RT should be performed preoperatively rather than postoperatively. Omission of preoperative RT is conditionally recommended in selected patients with lower risk of locoregional recurrence. Addition of chemotherapy before or after chemoradiation or after short-course RT is conditionally recommended. Nonoperative management is conditionally recommended if a clinical complete response is achieved after neoadjuvant treatment in selected patients. Inclusion of the rectum and mesorectal, presacral, internal iliac, and obturator nodes in the clinical treatment volume is recommended. In addition, inclusion of external iliac nodes is conditionally recommended in patients with tumors invading an anterior organ or structure, and inclusion of inguinal and external iliac nodes is conditionally recommended in patients with tumors involving the anal canal.

CONCLUSIONS

Based on currently published data, the American Society for Radiation Oncology task force has proposed evidence-based recommendations regarding the use of RT for rectal cancer. Future studies will look to further personalize treatment recommendations to optimize treatment outcomes and quality of life.

Unintended consequences of treating early rectal cancers for complete clinical response with chemoradiotherapy

The aim was to examine the current trend in rectal cancer, which is to extend ’watch-and-wait’ to earlier-stage tumors, not normally treated with chemoradiotherapy, to define the up-side and down-side regarding quality of life (QOL) and anorectal/sexual/urinary function from this approach. We reviewed the literature regarding a ‘watch-and-wait’ strategy after neoadjuvant chemoradiotherapy. The primary outcome measure was complete clinical response. Secondary measures included colostomy rate, functional outcomes and QOL. There is a trend to use chemoradiotherapy in earlier tumors using dose-escalation of radiation and/or additional chemotherapy, resulting in high rates of complete clinical response, which may impact adversely on QOL if radical surgery is subsequently required. Focusing on organ-preservation as the primary goal of treatment rather than overall functional outcomes and QOL for the whole population, may not provide patients with sufficient information for optimal decision-making.

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

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.

Behavioural Response Alteration in Caenorhabditis elegans to Urine After Surgical Removal of Cancer: Nematode-NOSE (N-NOSE) for Postoperative Evaluation

The technique used for cancer monitoring is essential for effective cancer therapy. Currently, several methods such as diagnostic imaging and biochemical markers have been used for cancer monitoring, but these are invasive and show low sensitivity. A previous study reported that Caenorhabditis elegans sensitively discriminated patients with cancer from healthy subjects, based on the smell of a urine sample. However, whether C. elegans olfaction can detect the removal of cancerous tumours remains unknown. This study was conducted to examine C. elegans olfactory behaviour to urine samples collected from 78 patients before and after surgery. The diagnostic ability of the technique termed Nematode-NOSE (N-NOSE) was evaluated by receiver operating characteristic (ROC) analysis. The ROC curve of N-NOSE was higher than those of classic tumour markers. Furthermore, we examined the change in C. elegans olfactory behaviour following exposure to preoperative and postoperative samples. The results suggest that a reduction in attraction indicates the removal of the cancerous tumour. This study may lead to the development of a noninvasive and highly sensitive tool for evaluating postoperative cancer patients.