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Neoadjuvant Chemoradiotherapy Enhances Tumor Response in LARC
According to data that are being presented at the virtual ESMO 23rd World Congress on Gastrointestinal Cancer, neoadjuvant chemoradiotherapy (CRT) was found to enhance the tumor immunologic response in patients with locally advanced rectal cancer (LARC).
“Preoperative chemoradiotherapy followed by total mesorectal excision is the standard treatment for locally advanced rectal cancer,” explained the investigators.
“Despite improvements of neoadjuvant treatments, local recurrence is still problematic. Besides well-known clinical prognostic factors, more reliable predictive factors must be identified for predicting treatment response and prognosis of LARC," they continued.
Thus, the investigators aimed to examine the clinical, laboratory, radiologic, and histopathologic parameters that predict responses to neoadjuvant therapy.
Between 2015 and 2018, a total of 51 patients (median age 64) with LARC who received neoadjuvant CRT at the Antalya Training and Research Hospital were enrolled in the study.
The main end points of the study were demographic characteristics of patients, pre-treatment laboratory parameters, grade, ulcer, and necrosis in endoscopic biopsy materials, lymphovascular invasion (LVI) in resection materials after treatment, perineural invasion (PNI) presence, and degree of intratumoral lymphocytic response.
Overall, 21% of patients in the clinical stage were T2, 53% were T3, and 26% were T4, with a node positivity rate of 77%. The pathologic grade was mostly grade 2. The overall response rate (ORR) was 45.4%. According to Modified Ryan criteria, the regression grade 0 and 1 (group 1: complete and near complete response) rate was 17.6% and 5.9%; grade 2 (group 2: partial response) was 51%; and grade 3 (group 3: poor/no response) was 3.9%.
Clinical characteristics, chemotherapy regimens and radiologic response rates were similar between all cohorts. In all, 27.6% of patients with radiological responders had no pathologic response. The positive lymph node metastases (pN+) rate was 17% in patients with “good” pathologic response. The LVI rate was higher for patients in group 3. The neutrophil-lymphocyte ratio (NLR) was similar between the cohorts, but target lesion revascularization (TLR) was different between groups 1 and 3, and was higher than 135 in patients who had regression grade 2 or 3.
According to regression analysis, perineural invasion (PNI), NLR ≥2.9 and TLR ≥135 were independent predictive factors for regression grades. At the median follow up of 26 months, the median disease-free survival (DFS) was 19.58-4.6 (95% CI, 10.5-28.67) months and were similar between regression grades. However, regression grades, NLR and carcinoembryonic antigen (CEA) were predictive factors for median DFS. The median overall survival (OS) was not reached.
“We concluded that neoadjuvant CRT enhances the tumor immunologic response. Initially high NLR and TLR were predictive factors for neoadjuvant treatment response in the patients with LARC. Initially high CEA levels, LVI and PNI were poor prognostic factors. Radiological responses cannot always be correlated with pathological responses. Not only the primary tumor, but also lymph nodes must be evaluated carefully,” investigators concluded.—Emily Bader
Acun M, Alikanoglu A, Onder, A, et al. The prognostic and predictive factors for patients with locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy. Presented at: the ESMO 23rd World Congress on Gastrointestinal Cancer; June 30-July 3, 2021; virtual. Abstract P-291.
