Clinical significance of enlarged lateral pelvic lymph nodes before and after preoperative chemoradiotherapy for rectal cancer

Abstract

Abstract. Preoperative chemoradiotherapy (CRT) with total mesorectal excision (TME) is the widely accepted treatment for rectal cancer (RC) in Western countries. However, there remains controversy as to whether preoperative CRT is useful in tumors that extend beyond the mesorectum, including metastasis to the lateral pelvic lymph nodes (LPLN). The aim of this study was to assess the prognostic significance of LPLN enlargement in patients with RC who receive preoperative CRT followed by TME without LPLN dissection. We evaluated the prognostic effect of radiographic LPLN enlargement before and after CRT, as well as the patients' clinicopathological and genetic profiles. Of the 104 patients investigated, pretreatment imaging identified 19 (18%) as LPLN-positive (>7 mm in diameter). Of these 19 patients, 7 (37%) exhibited LPLN downsizing to <7 mm following CRT. The median follow-up period was 52 months. The 5-year cancer-specific survival (CSS) or relapse-free survival (RFS) did not differ significantly between patients who did and those who did not have positive LPLN on pretreatment imaging. However, LPLN that remained positive after CRT were significantly associated with poorer 5-year CSS (73 vs. 84%, respectively; P=0.0052) and RFS (32 vs. 78%, respectively; P=0.0264). None of the patients whose LPLN were downsized to <7 mm following CRT developed recurrence; however, those with positive LPLN after CRT had a 55% higher recurrence rate, characterized by delayed local recurrence, a pattern that may be affected by certain chemokines. In conclusion, changes in initially positive LPLN (>7 mm) may predict the prognosis of patients with RC who receive preoperative CRT-TME. LPLN positivity after CRT was associated with shorter CSS and RFS. Strategies to improve patient survival may include selective LPLN dissection or more aggressive multimodality therapy.

Accuracy of F-18 FDG PET/CT with optimal cut-offs of maximum standardized uptake value according to size for diagnosis of regional lymph node metastasis in patients with rectal cancer

“…Patients were classified based on the long-axis diameter of the regional LN on CT images as small (≤ 7 mm; n = 118) and large (> 7 mm; n = 58) LN groups. The reference value for long-axis diameter was determined as 7 mm, because the partial volume effect is significant when the target of interest is smaller than 2 times of the PET/CT system’s full-width at half-maximum (FWHM) (< 8 mm) [ 18 ], and the long-axis diameter range on multiple detector CT has been reported as 7–10 mm for the diagnosis of metastatic regional LN [ 19 , 20 ]. This study was approved by the Institutional Review Board of our institution.…”

Evaluating predictive factors for determining the presence of lateral pelvic node metastasis in rectal cancer patients following neoadjuvant chemoradiotherapy

“…While the role of nCRT for LPNM has become clearer in recent years, it is well recognized that nCRT cannot eliminate all malignant cells within LPNs. The results of this study suggest that LPNM is influenced by both post-nCRT size and the sensitivity of LPN classification [19,23,24]. Oh et al [19] reported that persistent LPNs ≥ 5 mm on post-nCRT MRI were more significantly associated with residual tumour metastasis than responsive LPNs after nCRT (61.1% vs 0%, P = 0.001), and multivariable analysis revealed post-nCRT LPN size to be a significant and independent risk factor for LPNM (OR = 2.390; 95% CI = 1.104-4.069, P = 0.001).…”

“…Yamaoka et al [23] also found that in the nCRT group, the optimal cut-off value of post-nCRT LPN size was 5 mm, with a sensitivity of 71.4% and specificity of 85.3% for positive LPNM. Inoue et al [24], however, considered a 7 mm cut-off more appropriate. In our study, we set 5 mm as the cut-off for post-nCRT LPN size.…”

Feasibility of Assessing Prognostic Nutrition Index in Patients With Rectal Cancer Who Receive Preoperative Chemoradiotherapy

“…Histopathologic degree of tumor regression was based on the Guidelines for the Clinical and Pathologic Studies on Carcinoma of the Colorectum and was classified into 1 of the following 4 categories: grade 0, no necrosis or regressive changes; grade 1a, >⅔ vital residual tumor cells (VRTCs): grade 1b, approximately ⅓ VRTCs; grade 2, < ⅓ VRTCs; and grade 3, no VRTCs . Nonresponders were defined as patients with histopathological tumor regression grades 0–1b, and responders were defined as those with grades 2–3, as previously described …”