Prognostic Implications of Lateral Lymph Nodes in Rectal Cancer: A Population-Based Cross-sectional Study With Standardized Radiological Evaluation After Dedicated Training

BACKGROUND

There is an ongoing discussion regarding the prognostic implications of the presence, short-axis diameter, and location of lateral lymph nodes.

OBJECTIVE

To analyze lateral lymph node characteristics, the role of downsizing on restaging MRI, and associated local recurrence rates for patients with cT3-4 rectal cancer after MRI re-review and training.

DESIGN

Retrospective population-based cross-sectional study.

SETTINGS

This collaborative project was led by local investigators from surgery and radiology departments in 60 Dutch hospitals.

PATIENTS

A total of 3057 patients underwent rectal cancer surgery in 2016: 1109 had a cT3-4 tumor located ≤8 cm from the anorectal junction, of whom 891 received neoadjuvant therapy.

MAIN OUTCOME MEASURES

Local recurrence and (ipsi) lateral local recurrence rates.

RESULTS

Re-review identified 314 patients (35%) with visible lateral lymph nodes. Of these, 30 patients had either only long-stretched obturator (n = 13) or external iliac (n = 17) nodes, and both did not lead to any lateral local recurrences. The presence of internal iliac/obturator lateral lymph nodes (n = 284) resulted in 4-year local recurrence and lateral local recurrence rates of 16.4% and 8.8%, respectively. Enlarged (≥7 mm) lateral lymph nodes (n = 122) resulted in higher 4-year local recurrence (20.8%, 13.1%, 0%; p <.001) and lateral local recurrence (14.7%, 4.4%, 0%; p < 0.001) rates compared to smaller and no lateral lymph nodes, respectively. Visible lateral lymph nodes (HR 1.8 [1.1-2.8]) and enlarged lateral lymph nodes (HR 1.9 [1.1-3.5]) were independently associated with local recurrence in multivariable analysis. Enlarged lateral lymph nodes with malignant features had higher 4-year lateral local recurrence rates of 17.0%. Downsizing had no impact on lateral local recurrence rates. Enlarged lateral lymph nodes were found to be associated with higher univariate 4-year distant metastasis rates (36.4% vs 24.4%; p = 0.021), but this was not significant in multivariable analyses (HR 1.3 [0.9-1.]) and did not worsen overall survival.

LIMITATIONS

This study was limited by the retrospective design and total number of patients with lateral lymph nodes.

CONCLUSIONS

The risk of lateral local recurrence due to (enlarged) lateral lymph nodes was confirmed, but without the prognostic impact of downsizing after neoadjuvant therapy. These results point toward the incorporation of primary lateral lymph node size into treatment planning. See Video Abstract.

IMPLICACIONES PRONSTICAS DE LOS NDULOS LINFTICOS LATERALES EN EL CNCER DE RECTO UN ESTUDIO TRANSVERSAL DE BASE POBLACIONAL CON EVALUACIN RADIOLGICA ESTANDARIZADA DESPUS DE UN ENTRENAMIENTO ESPECFICO

ANTECEDENTES:Hay una discusión en curso acerca de las implicaciones pronósticas de la presencia, el diámetro del eje corto y la ubicación de los nódulos linfáticos laterales.OBJETIVO:Analizar las características de los nódulos linfáticos laterales, el rol de la reducción de tamaño en la IRM de reestratificación y las tasas de recurrencia local asociadas para pacientes con cáncer de recto cT3-4 después de una nueva revisión y entrenamiento de IRM.DISEÑO:Estudio transversal retrospectivo poblacional.CONFIGURACIÓN:Este proyecto colaborativo fue dirigido por investigadores locales de los departamentos de cirugía y radiología en 60 hospitales holandeses.PACIENTES:3057 pacientes fueron operados de cáncer de recto en 2016: 1109 tenían tumor cT3-4 ubicado a ≤8 cm de la unión anorrectal de los cuales 890 recibieron terapia neoadyuvante.INTERVENCIONES(S):Ninguna.PRINCIPALES MEDIDAS DE RESULTADO:recurrencia local y tasas de recurrencia local ipsilateral.RESULTADOS:Una nueva revisión identificó a 314 pacientes (35%) con nódulos linfáticos laterales visibles. 30 de estos pacientes tenían solo nódulos obturadores estirados (n = 13) o ilíacos externos (n = 17) y ambos no provocaron recurrencias locales laterales. La presencia de nódulos linfáticos laterales ilíacos internos/obturadores (n = 284) dio como resultado tasas de recurrencia local y recurrencia local lateral a los 4 años del 16.4% y el 8.8%, respectivamente. Los nódulos linfáticos laterales agrandados (≥7 mm) (n = 122) resultaron en una mayor recurrencia local a los 4 años (20.8%, 13.1%, 0%, p < 0.001) y recurrencia local lateral (14.7%, 4.4%, 0%, p < 0.001) en comparación con nódulos linfáticos más pequeños y sin nódulos linfáticos laterales, respectivamente. Los nódulos linfáticos laterales visibles (índice de riesgo 1,8 (1,1-2,8)) y los nódulos linfáticos laterales agrandados (índice de riesgo 1.9 (1.1-3.5)) se asociaron de forma independiente con la recurrencia local en el análisis multivariable. Los nódulos linfáticos laterales agrandados con características malignas tuvieron tasas de recurrencia local lateral a 4 años más altas del 17.0%. La reducción de tamaño no tuvo impacto en las tasas de recurrencia local lateral. Los nódulos linfáticos laterales agrandados se asociaron con tasas univariadas más altas de metástasis a distancia a los 4 años (36.4%, 24.4%, p = 0.021), pero no en el análisis multivariable (índice de riesgo 1.3 (0.9-1.8)), y no empeoró la supervivencia general.LIMITACIONES:Este estudio estuvo limitado por el diseño retrospectivo y el número total de pacientes con nódulos linfáticos laterales.CONCLUSIONES:Se confirmó el riesgo de recurrencia local lateral debido a los nódulos linfáticos laterales (agrandados), pero sin el impacto pronóstico de la reducción después de la terapia neoadyuvante. Estos resultados apuntan hacia la incorporación del tamaño del nódulo linfático lateral primario en la planificación del tratamiento. (Traducción-Dr. Aurian Garcia Gonzalez ).

Locoregional Failure During and After Short-course Radiotherapy Followed by Chemotherapy and Surgery Compared With Long-course Chemoradiotherapy and Surgery: A 5-Year Follow-up of the RAPIDO Trial

OBJECTIVE

To analyze risk and patterns of locoregional failure (LRF) in patients of the RAPIDO trial at 5 years.

BACKGROUND

Multimodality treatment improves local control in rectal cancer. Total neoadjuvant treatment (TNT) aims to improve systemic control while local control is maintained. At 3 years, LRF rate was comparable between TNT and chemoradiotherapy in the RAPIDO trial.

METHODS

A total of 920 patients were randomized between an experimental (EXP, short-course radiotherapy, chemotherapy, and surgery) and a standard-care group (STD, chemoradiotherapy, surgery, and optional postoperative chemotherapy). LRFs, including early LRF (no resection except for organ preservation/R2 resection) and locoregional recurrence (LRR) after an R0/R1 resection, were analyzed.

RESULTS

Totally, 460 EXP and 446 STD patients were eligible. At 5.6 years (median follow-up), LRF was detected in 54/460 (12%) and 36/446 (8%) patients in the EXP and STD groups, respectively ( P =0.07), in which EXP patients were more often treated with 3-dimensional-conformed radiotherapy ( P =0.029). In the EXP group, LRR was detected more often [44/431 (10%) vs. 26/428 (6%); P =0.027], with more often a breached mesorectum (9/44 (21%) vs. 1/26 (4); P =0.048). The EXP treatment, enlarged lateral lymph nodes, positive circumferential resection margin, tumor deposits, and node positivity at pathology were the significant predictors for developing LRR. Location of the LRRs was similar between groups. Overall survival after LRF was comparable [hazard ratio: 0.76 (95% CI, 0.46-1.26); P =0.29].

CONCLUSIONS

The EXP treatment was associated with an increased risk of LRR, whereas the reduction in disease-related treatment failure and distant metastases remained after 5 years. Further refinement of the TNT in rectal cancer is mandated.

New Opportunities for Minimizing Toxicity in Rectal Cancer Management

Advances in multimodal management of locally advanced rectal cancer (LARC), consisting of preoperative chemotherapy and/or radiotherapy followed by surgery with or without adjuvant chemotherapy, have improved local disease control and patient survival but are associated with significant risk for acute and long-term morbidity. Recently published trials, evaluating treatment dose intensification via the addition of preoperative induction or consolidation chemotherapy (total neoadjuvant therapy [TNT]), have demonstrated improved tumor response rates while maintaining acceptable toxicity. In addition, TNT has led to an increased number of patients achieving a clinical complete response and thus eligible to pursue a nonoperative, organ-preserving, watch and wait approach, thereby avoiding toxicities associated with surgery, such as bowel dysfunction and stoma-related complications. Ongoing trials using immune checkpoint inhibitors in patients with mismatch repair-deficient tumors suggest that this subgroup of patients with LARC could potentially be treated with immunotherapy alone, sparing them the toxicity associated with preoperative treatment and surgery. However, the majority of rectal cancers are mismatch repair-proficient and less responsive to immune checkpoint inhibitors and require multimodal management. The synergy noted in preclinical studies between immunotherapy and radiotherapy on immunogenic tumor cell death has led to the design of ongoing clinical trials that explore the benefit of combining radiotherapy, chemotherapy, and immunotherapy (mainly of immune checkpoint inhibitors) and aim to increase the number of patients eligible for organ preservation.

Risk and location of distant metastases in patients with locally advanced rectal cancer after total neoadjuvant treatment or chemoradiotherapy in the RAPIDO trial

INTRODUCTION

Although optimising rectal cancer treatment has reduced local recurrence rates, many patients develop distant metastases (DM). The current study investigated whether a total neoadjuvant treatment strategy influences the development, location, and timing of metastases in patients diagnosed with high-risk locally advanced rectal cancer included in the Rectal cancer And Pre-operative Induction therapy followed by Dedicated Operation (RAPIDO) trial.

MATERIAL AND METHODS

Patients were randomly assigned to short-course radiotherapy followed by 18 weeks of CAPOX or FOLFOX4 before surgery (EXP), or long-course chemoradiotherapy with optional postoperative chemotherapy (SC-G). Assessments for metastatic disease were performed pre- and post-treatment, during surgery, and 6, 12, 24, 36, and 60 months postoperatively. From randomisation, differences in the occurrence of DM and first site of metastasis were evaluated.

RESULTS

In total, 462 patients were evaluated in the EXP and 450 patients in the SC-G groups. The cumulative probability of DM at 5 years after randomisation was 23% [95% CI 19-27] and 30% [95% CI 26-35] (HR 0.72 [95% CI 0.56-0.93]; P = 0.011) in the EXP and SC-G, respectively. The median time to DM was 1.4 (EXP) and 1.3 years (SC-G). After diagnosis of DM, median survival was 2.6 years [95% CI 2.0-3.1] in the EXP and 3.2 years [95% CI 2.3-4.1] in the SC-G groups (HR 1.39 [95% CI 1.01-1.92]; P = 0.04). First occurrence of DM was most often in the lungs (60/462 [13%] EXP and 55/450 [12%] SC-G) or the liver (40/462 [9%] EXP and 69/450 [15%] SC-G). A hospital policy of postoperative chemotherapy did not influence the development of DM.

CONCLUSIONS

Compared to long-course chemoradiotherapy, total neoadjuvant treatment with short-course radiotherapy and chemotherapy significantly decreased the occurrence of metastases, particularly liver metastases.

The immune microenvironment landscape shows treatment-specific differences in rectal cancer patients

Neoadjuvant therapy is the cornerstone of modern rectal cancer treatment. Insights into the biology of tumor responses are essential for the successful implementation of organ-preserving strategies, as different treatments may lead to specific tumor responses. In this study, we aim to explore treatment-specific responses of the tumor microenvironment. Patients with locally advanced adenocarcinoma of the rectum who had received neo-adjuvant chemotherapy (CT), neo-adjuvant radiochemotherapy (RCT), neo-adjuvant radiotherapy with a long-interval (LRT) or short-interval (SRT) or no neoadjuvant therapy (NT) as control were included. Multiplex-immunofluorescence was performed to determine the presence of cytotoxic T-cells (T-cyt; CD3+CD8+), regulatory T-cells (T-reg; CD3+FOXP3+), T-helper cells (T-helper; CD3+CD8-FOXP3-), B cells (CD20+), dendritic cells (CD11c+) and tumor cells (panCK+). A total of 80 rectal cancer patients were included. Treatment groups were matched for gender, tumor location, response to therapy, and TNM stage. The pattern of response (shrinkage vs. fragmentation) was, however, different between treatment groups. Our analyses reveal that RCT-treated patients exhibited lower stromal T-helper, T-reg, and T-cyt cells compared to other treatment regimens. In conclusion, we demonstrated treatment-specific differences in the immune microenvironment landscape of rectal cancer patients. Understanding the underlying mechanisms of this landscape after a specific therapy will benefit future treatment decisions.

Hypofractionated radiotherapy combined with targeted therapy or immunotherapy: Dutch survey on current practice, knowledge and challenges

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Radiotherapy referral during targeted therapy or immunotherapy occurs regularly.

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There is a knowledge gap regarding the implications of combined therapy.

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There is no consensus on expected toxicity of combined therapy.

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Multidisciplinary protocols regarding combined therapy are often not available.

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The application of radiotherapy treatment adaptations varies widely when combined with different systemic treatments.

Introduction

With the introduction of tyrosine kinase inhibitors and systemic antibodies, including immune checkpoint inhibitors, the survival of advanced-stage cancer patients has improved for many tumor types. These patients are increasingly referred for radiotherapy, but it is unclear whether radiotherapy combined with these drugs is safe. No international guidelines exist on whether or how to combine these drugs with radiotherapy. Therefore, we investigated the current clinical practice in the Netherlands regarding hypofractionated radiotherapy in patients using targeted drugs and immunotherapy.

Materials and methods

We sent a survey to all 21 Dutch radiotherapy institutes. Dedicated radiation oncologists, medical oncologists and pulmonologists were asked to fill out the survey. The questions explored their familiarity with the combination of targeted drugs and immunotherapy with radiotherapy, the encountered clinical difficulties and factors influencing treatment decisions.

Results

The survey was filled out by 54 respondents from 19 different institutes. The median annual number of patients per radiation oncologist referred for radiotherapy when using targeted drugs or immunotherapy was 10 and 15, respectively. Despite this high number, only 11% of the radiation oncologists stated that they had sufficient information (resources) for adequate treatment decision making. Among all physicians, 44% stated that there was insufficient knowledge within their institute regarding this topic. Only 17% stated that there was a multidisciplinary protocol available. The application of radiotherapy treatment adaptations (technique, dose, fractionation, field size) varied widely. Generally, there seemed to be no consensus regarding the expected toxicity of combined drug-radiotherapy treatments and the expected risk of tumor flare upon temporary drug discontinuation.

Conclusion

There is no consensus amongst involved medical specialties on expected toxicity. Consequently, it is necessary to perform clinical studies examining the safety of combined drug-radiotherapy treatments, to add radiotherapy to phase I-III clinical trials for new drugs and to incorporate outcomes into multidisciplinary, evidence-based guidelines.

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.

EUS-guided fiducial marker placement for radiotherapy in rectal cancer: feasibility of two placement strategies and four fiducial types

Background and study aims  To facilitate image guidance during radiotherapy of rectal cancer, we investigated the feasibility of fiducial marker placement. This study aimed to evaluate technical success rate and safety of two endoscopic ultrasound (EUS)-guided placement strategies and four fiducial types for rectal cancer patients. Patients and methods  This prospective multicenter study included 20 participants who were scheduled to undergo rectal cancer treatment with neoadjuvant short-course radiotherapy or chemoradiation. EUS-guided endoscopy was used for fiducial placement at the tumor site (n = 10) or in the mesorectal fat and in the tumor (n = 10). Four fiducial types were used (Visicoil 0.75 mm, Visicoil 0.50 mm, Cook, Gold Anchor). The endpoints were technical success rate and retention of fiducials, the latter of which was evaluated on cone-beam computed tomography scans during the first five radiotherapy fractions. Results  A total of 64 fiducials were placed in 20 patients. For each fiducial type, at least three fiducials were successfully placed in all patients. Technical failure consisted of fiducial blockage within the needle (n = 2) and ejection of two preloaded fiducials at once (n = 4). No serious adverse events were reported. In three patients, one of the fiducials was misplaced without clinical consequences; two in the prostate and one in the intraperitoneal cavity. After a median time of 17 days after placement (range 7 - 47 days), a total of 42/64 (66 %) fiducials were still present (24/44 intratumoral vs. 18/20 mesorectal fiducials, P  = 0.009). Conclusions  Placement of fiducials in rectal cancer patients is feasible, however, retention rates for intratumoral fiducials were lower (55 %) than for mesorectal fiducials (90 %).

Robust dose planning objectives for mesorectal radiotherapy of early stage rectal cancer - A multicentre dose planning study

BACKGROUND AND PURPOSE

Organ preservation strategies are increasingly being explored for early rectal cancer. This requires revision of target volumes according to disease stage, as well as new guidelines for treatment planning. We conducted an international, multicentre dose planning study to develop robust planning objectives for modern radiotherapy of a novel mesorectal-only target volume, as implemented in the STAR-TReC trial (NCT02945566).

MATERIALS AND METHODS

The published literature was used to establish relevant dose levels for organ at risk (OAR) plan optimisation. Ten representative patients with early rectal cancer were identified. Treatment scans had mesorectal target volumes as well as bowel cavity, bladder and femoral heads outlined, and were circulated amongst the three participating institutions. Each institution produced plans for short course (SCRT, 5 × 5 Gy) and long course (LCRT, 25 × 2 Gy) treatment, using volumetric modulated arc therapy on different dose planning systems. Optimisation objectives for OARs were established by determining dose metric objectives achievable for ≥90% of plans.

RESULTS

Sixty plans, all fulfilling target coverage criteria, were produced. The planning results and literature review suggested optimisation objectives for SCRT: V 10Gy < 180 cm3, V 18Gy < 110 cm3, V 23Gy < 85 cm3 for bowel cavity; V 21Gy < 15% and V 25Gy < 5% for bladder; and V 12.5Gy < 11% for femoral heads. Corresponding objectives for LCRT: V 20Gy < 180 cm3, V 30Gy < 130 cm3, V 45Gy < 90 cm3 for bowel cavity; V 35Gy < 22% and V 50Gy < 7% for bladder; and V 25Gy < 15% for femoral heads. Constraints were validated across all three institutions.

CONCLUSION

We utilized a multicentre planning study approach to develop robust planning objectives for mesorectal radiotherapy for early rectal cancer.

Preoperative radiotherapy combined with total mesorectal excision for resectable rectal cancer

BACKGROUND

Short-term preoperative radiotherapy and total mesorectal excision have each been shown to improve local control of disease in patients with resectable rectal cancer. We conducted a multicenter, randomized trial to determine whether the addition of preoperative radiotherapy increases the benefit of total mesorectal excision.

METHODS

We randomly assigned 1861 patients with resectable rectal cancer either to preoperative radiotherapy (5 Gy on each of five days) followed by total mesorectal excision (924 patients) or to total mesorectal excision alone (937 patients). The trial was conducted with the use of standardization and quality-control measures to ensure the consistency of the radiotherapy, surgery, and pathological techniques.

RESULTS

Of the 1861 patients randomly assigned to one of the two treatment groups, 1805 were eligible to participate. The overall rate of survival at two years among the eligible patients was 82.0 percent in the group assigned to both radiotherapy and surgery and 81.8 percent in the group assigned to surgery alone (P=0.84). Among the 1748 patients who underwent a macroscopically complete local resection, the rate of local recurrence at two years was 5.3 percent. The rate of local recurrence at two years was 2.4 percent in the radiotherapy-plus-surgery group and 8.2 percent in the surgery-only group (P<0.001).

CONCLUSIONS

Short-term preoperative radiotherapy reduces the risk of local recurrence in patients with rectal cancer who undergo a standardized total mesorectal excision.

No downstaging after short-term preoperative radiotherapy in rectal cancer patients

PURPOSE

In retrospective studies, total mesorectal excision (TME) surgery has been demonstrated to result in a reduction in the number of local recurrences of rectal cancer. Reports on improved local control after preoperative, hypofractionated radiotherapy have led to the introduction of a randomized multicenter trial to evaluate the effect of TME surgery with and without preoperative radiotherapy. Treatment with preoperative radiotherapy might have an effect on the pathologic characteristics that determine staging of rectal cancer. We investigated the occurrence of downstaging in rectal cancer patients treated with and without preoperative radiotherapy.

PATIENTS AND METHODS

We analyzed the differences in tumor size, number of examined lymph nodes, tumor-node-metastasis stage, and histopathologic features in 1,321 patients entered onto a randomized trial. The trial compared preoperative radiotherapy (5 x 5 Gy) followed by TME surgery with TME surgery alone. Patients who had an interval of more than 10 days between the start of radiotherapy and surgery were excluded from analysis.

RESULTS

Differences were observed in tumor size (P <.001) and total number of examined lymph nodes (P <.001). No difference in tumor or node classification was detected. The irradiated group demonstrated more poorly differentiated tumors as well as more mucinous tumors.

CONCLUSION

In rectal cancer patients, short-term, preoperative radiotherapy with 5 x 5 Gy does not lead to downstaging if the interval between the start of radiotherapy and surgery does not exceed 10 days.

Local recurrence in patients with rectal cancer diagnosed between 1988 and 1992: a population-based study in the west Netherlands

AIMS

We carried out a population-based study of local recurrence rates in curatively resected patients with rectal cancer, diagnosed between 1988 and 1992. The first objective was to make an inventory of the overall local recurrence rate after non-standardized conventional surgery, inter-institutional recurrence rate variability, and correlations between patient- and tumour-related factors and recurrence rate. A second objective was to investigate the compliance to guidelines for post-operative radiotherapy.

METHODS

Data were obtained from the Comprehensive Cancer Centre West. The study comprised 1105 patients from 12 hospitals. Of these patients, 437 were ineligible because of missing medical records, no carcinoma, incorrect registration, no laparotomy, non-curative resection, or loss to follow-up.

RESULTS

The overall local recurrence rate was 22.5% with a range of 9-36% between the hospitals. These differences were not significant. Dukes' Astler-Coller stage, tumour location, and residual tumour were significant independent prognostic factors for the risk of local recurrence. Indications for post-operative radiotherapy were Dukes' Astler-Coller B2 and C tumours, positive surgical margins, and tumour spill. Compliance to the guidelines for radiotherapy was only 50%. However, no significant difference in recurrence rate was found between patients treated according to the guidelines and those not treated according to the guidelines.

CONCLUSION

This study shows a large variability in local recurrence rate between the participating hospitals and confirms that the risk of recurrence in primary rectal cancer is dependent on Dukes' Astler-Coller stage, tumour location and residual tumour. Furthermore, this study contributes to the discussion about the feasibility of guidelines for post-operative radiotherapy.