Optimal Size Criteria for Lateral Lymph Node Dissection After Neoadjuvant Chemoradiotherapy for Rectal Cancer

Abstract

BACKGROUND: Although chemoradiotherapy followed by radical surgery without lateral lymph node dissection is the current standard treatment in patients with rectal cancer, recent studies have demonstrated the benefits of adding lateral lymph node dissection to total mesorectal excision in patients with suspected lateral lymph node metastasis. However, the optimal indication for lateral lymph node dissection after chemoradiotherapy has not been determined. OBJECTIVE: This study aimed to establish the optimal indication for lateral lymph node dissection after chemoradiotherapy in patients with rectal cancer. DESIGN: This is a retrospective study. SETTINGS: This study was conducted at a single referral hospital. PATIENTS: A total of 279 patients with rectal cancer who underwent chemoradiotherapy followed by radical surgery between 2007 and 2018 were retrospectively enrolled. MAIN OUTCOME MEASURES: The largest lateral lymph nodes on CT were retrospectively assessed and compared with the pathologic results of dissected lateral lymph nodes and recurrences in lateral lymph node areas. RESULTS: The incidence of lateral lymph node metastasis after chemoradiotherapy was estimated to be 9.3%. Although patients with lateral lymph node metastasis frequently developed distant recurrence, 40.4% survived for >5 years without recurrence. An analysis of the lateral lymph node sizes showed that lateral lymph node size ≥8 mm before chemoradiotherapy was the optimal criterion for lateral lymph node dissection, with a sensitivity and specificity of 92.3% and 78.7%. Using this criterion, 72.0% of the patients could be spared lateral lymph node dissection. LIMITATIONS: Because of the retrospective nature of the present study, the selection of patients who underwent lateral lymph node dissection was biased. CONCLUSIONS: The optimal indication for lateral lymph node dissection was lateral lymph node size ≥8 mm before chemoradiotherapy. Cancer could be eradicated in >30% of patients with lateral lymph node metastasis by dissecting metastatic lateral lymph nodes. See Video Abstract at http://links.lww.com/DCR/B428. CRITERIOS DE TAMAÑO ÓPTIMO PARA LA DISECCIÓN DE GANGLIOS LINFÁTICOS LATERALES DESPUÉS DE LA QUIMIORRADIOTERAPIA NEOADYUVANTE PARA EL CÁNCER DE RECTO ANTECEDENTES: Aunque la quimiorradioterapia seguida por cirugía radical sin disección de ganglios linfáticos laterales es el tratamiento estándar actual en pacientes con cáncer de recto, estudios recientes han demostrado beneficios de agregar disección de ganglios linfáticos laterales a la escisión mesorrectal total en pacientes con sospecha de metástasis de ganglios linfáticos laterales. Sin embargo, no se ha determinado la indicación óptima para la disección de los ganglios linfáticos laterales después de la quimiorradioterapia. OBJETIVO: Este estudio tuvo como objetivo establecer la indicación óptima para la disección de los ganglios linfáticos laterales después de la quimiorradioterapia en pacientes con cáncer de recto. DISEÑO: Estudio retrospectivo. ENTORNO CLINICO: Este estudio se realizó en un solo hospital de referencia. PACIENTES: Se inscribieron retrospectivamente un total de 279 pacientes con cáncer de recto que se sometieron a quimiorradioterapia seguida por cirugía radical entre 2007 y 2018. PRINCIPALES MEDIDAS DE VALORACION: Los ganglios linfáticos laterales más grandes en la tomografía computarizada se evaluaron retrospectivamente y se compararon con los resultados patológicos de los ganglios linfáticos laterales disecados y recidivas en las áreas de los ganglios linfáticos laterales. RESULTADOS: Se estimó que la incidencia de metástasis en los ganglios linfáticos laterales después de la quimiorradioterapia fue del 9,3%. Aunque los pacientes con metástasis en los ganglios linfáticos laterales con frecuencia desarrollaron recurrencia a distancia, el 40,4% sobrevivió durante más de 5 años sin recurrencia. Un análisis de los tamaños de los ganglios linfáticos laterales mostró que la mayor dimensión de los ganglios linfáticos laterales ≥ 8 mm antes de la quimiorradioterapia eran el criterio óptimo para la disección de los ganglios linfáticos laterales, con una sensibilidad y especificidad del 92,3% y 78,7%, respectivamente. Utilizando este criterio, el 72,0% de los pacientes podría evitarse la disección de los ganglios linfáticos laterales. LIMITACIONES: Debido a la naturaleza retrospectiva del presente estudio, la selección de pacientes que fueron sometidos a disección de ganglios linfáticos laterales fue sesgada. CONCLUSIÓN: La indicación óptima para la disección de los ganglios linfáticos laterales fue la dimensión mayor de los ganglios linfáticos laterales ≥ 8 mm antes de la quimiorradioterapia. El cáncer se podría erradicar en más del 30% de los pacientes con metástasis en los ganglios linfáticos laterales disecando los ganglios linfáticos laterales metastásicos. Consulte Video Resumen en http://links.lww.com/DCR/B428.

Management of Clinically Involved Lateral Lymph Node Metastasis in Locally Advanced Rectal Cancer: A Radiation Dose Escalation Study

“…by the Lateral Node Study Consortium, a baseline SA of 7 mm was adopted by the cut-off value, and 20% LLR rate was observed in those patients. However, for the patients with baseline LLN SA >5 mm in that study, the LLR rate was also approximately 16% (23). Indeed, LLN SA >5 mm on MRI scans has been proposed as the best cut-off standard in several studies (10,13,14).…”

“…According to previous studies, baseline LLNs SA cut-off from 5 to 10 mm were adopted as the clinically positive standard before nCRT (13,(23)(24)(25). In a recent large-scale study conducted The bold type indicates that the P value is statistically significant.…”

Lateral lymph node dissection in rectal cancer: State of the art review

“…In the JCOG0212 study, an enlarged LLN was defined as 10 mm short-axis [11]. Kawai et al performed a retrospective study to determine the optimal size criterion for the indication for a LLND, which was 8 mm long-axis according to their results with a sensitivity of 92.3% and a specificity of 78.7% [24]. Five mm shortaxis on the pre-treatment MRI was used by Kroon et al [22] Also, Kim et al have investigated the pretreatment risk factors for developing an LLR [25].…”

Lateral pelvic lymph nodes for rectal cancer: A review of diagnosis and management

“…The cut-off for LPLN size varies from 4 mm to 12 mm. Similar to those for PRLNs, various morphological criteria have also been described, including irregular border, mixed signal intensity, speculated appearance, indistinct border, and mottled heterogeneous appearance[ 22 - 34 ]. In a comparison of area under the curve-based diagnoses using 5-mm and 10-mm cut-offs for the short axis, we found values of 0.7418 on the right and 0.7593 on the left at 5-mm, and of 0.6326 on the right and 0.6559 on the left at 10-mm[ 35 ].…”