METHODS
Fifty-six patients who underwent neoadjuvant CRT and curative surgery for locally advanced rectal
cancer (LARC) were analyzed retrospectively. Pre-CRT and post-CRT hematologic parameters were
recorded. The link between NLR and clinical outcomes was explored.
RESULTS
The receiver operating characteristic analysis revealed appropriate cut-off values of 2.87 for pre-CRT
NLR associated with good pathological response and 8.68 for post-CRT NLR predicting survival. The
low pre-CRT NLR group had better outcomes in terms of good pathological response compared to the
high pre-CRT NLR group (OR 4.15, 95% CI 1.23-13.76, p=0.021). However, the analysis failed to show
the correlation between NLR and pCR (OR 2.74, 95% CI 0.37-20.15, p=0.320). Patients with elevated
post-CRT NLR had significantly worse 5-year overall survival (OS), disease-free survival (DFS) and
local regional recurrence-free survival (LRRFS) rates compared to low post-CRT NLR in multivariate
analysis (46.6% vs. 74.4%, p=0.020; 35.3% vs. 71.9%, p=0.018; 40.8% vs. 78.1%, p=0.006).
CONCLUSION
High pre-CRT NLR might be used as a poor pathological tumor response predictor in LARC patients
treated with neoadjuvant CRT. In addition, low post-CRT NLR is associated with favorable OS, DFS,
and LRRFS. Therefore, easily accessible and cost-effective NLR can be considered as a potential predictive
marker to identify patients and establish personalized treatment strategies.
Keywords: Neoadjuvant chemoradiotherapy; neutrophil-to-lymphocyte ratio; pathological tumor response; prognosis; rectal cancer; survival
Accumulating evidence has supported that systemic
inflammation has been recognized as a hallmark of cancer
development and progression. The systemic inflammatory
response plays a crucial role in the prognosis of
several solid tumors due to interactions of the tumor microenvironment
resulting in tumor growth and spread.
[
In this study, our primary goal is to investigate the
relationship between baseline and post-treatment NLR
levels and response to neoadjuvant CRT in terms of
pCR and good pathological response. We also aimed
to evaluate the prognostic ability of pre-CRT and post-
CRT NLR on survival outcomes.
Data Collection
Patient demographics, surgical and oncologic outcomes
were extracted through the patient archive files and electronic
medical records system, including age, gender,
tumor location, carcinoembryonic antigen (CEA), albumin,
uric acid, hemoglobin, neutrophil, lymphocyte,
monocyte and platelet counts, clinical T and N stage,
type of surgery, lymphovascular invasion (LVI), perineural
invasion (PNI), pathological TNM stage, recurrence,
distant metastasis, and death. The NLR was calculated
as the neutrophil count divided by the lymphocyte
count and was categorized as pre-CRT and post-CRT.
Pretreatment Assessment
The clinical workup included physical examination,
blood analysis, colonoscopy, computed tomography
scan (CT) of the abdomen, pelvis and chest, and pelvic
magnetic resonance imaging for pretreatment evaluation.
In addition, positron emission tomography was
performed on several patients. The seventh edition of
the TNM classification of the American Joint Committee
on Cancer was used to define the clinical stage.
Treatment
Three-dimensional radiotherapy was applied with a median
radiation dose of 50.4 Gy. Radiotherapy was performed
to the whole pelvis with 45 Gy in 25 fractions,
followed by a boost of 5.4 Gy to the primary tumor in 3 fractions. The gross tumor volume (GTV) contained
primary tumor and involved lymph nodes visible on
imaging. The clinical target volume (CTV) was defined
including the entire mesorectum and associated lymph
nodes. The lymph nodes consisted of obturator and internal
iliac lymph nodes for all T stages and external iliac
lymph nodes for T4 tumors. The CTV was enlarged
1-1.5 cm in adjacent organs with gross tumor invasion
for T4 tumors. The boost volume covered the GTV with
a 2 cm margin superiorly-inferiorly and at these levels
with the mesorectum and presacral space. The CTV was
expanded 5-10 mm to create the planning target volume.
kV imaging was done daily or every other day for
set-up accuracy. The treatment was applied with a full
bladder to minimize small bowel toxicity.
Concomitant chemotherapy was administered, except for 4 patients who could not receive chemotherapy due to their age and comorbidities during radiotherapy. Intravenous 5-fluorouracil (5-FU) or oral capecitabine chemotherapy regimens were used. In the 1st and 5th weeks of RT, 425 mg/m2/day 5-FU and 20 mg/m2/day leucovorin were given. Capecitabine was administered at 825 mg/m2/twice daily during the entire radiotherapy period. All patients underwent curative surgery including TME and pelvic node dissection 4-12 weeks after the completion of neoadjuvant CRT, and adjuvant chemotherapy was applied.
Pathological Assessment of Response to Chemoradiation
As described by previous reports by Ryan et al.[6] the
pathologic response to neoadjuvant CRT was determined
by the amount of viable malignancy versus the
amount of fibrosis and was defined in 5 tumor regression
grades (TRG). In brief, TRG1 was defined as no
viable cancer cells (complete response); TRG2 as remaining
of single cells or rare small groups of cancer
cells (near-complete response); TRG3 as the presence
of residual cancer with predominantly fibrosis (partial
response); TRG4 as residual cancer outgrowing fibrosis;
TRG5 as extensive residual cancer without fibrosis.
The pCR was defined as the absence of all malignant
cells, a good pathological response to neoadjuvant
CRT was defined as TRG1-3, while a poor pathological
response was defined as TRG4-5.
Follow-up
Patients were followed up every 3 months within the
first 2 years, every 6 months in the following 3 years, and
annually thereafter. Physical examinations, complete blood count, blood chemistry, CEA were performed
at each follow-up. Patients were evaluated with chest
and abdominal CT scan at 6-month intervals. Total
colonoscopy was performed at 1 year after surgery and
every 2 years thereafter. Based on clinical, radiologic
evaluations, or histological findings, any recurrence in
the pelvic cavity was defined as locoregional recurrence,
any recurrence outside the pelvic cavity, or metastasis in
solid organs, was defined as distant metastasis.
Statistical Analysis
The primary endpoints were pCR and good pathological
response to neoadjuvant CRT by TRG stages
as previously described. The secondary clinical outcomes
of interest were overall survival (OS), disease
free survival (DFS), and local-regional recurrence-free
survival (LRRFS). OS was defined as the time from the
date of diagnosis to the date of death or last followup.
The time from the date of diagnosis to the date of
occurence of local or/and distant failure, or death, or
last follow-up was calculated as DFS; the time from the
date of diagnosis to the local recurrence, or death, or
last follow-up was calculated as LRRFS.
The statistical analyses were performed with IBM SPSS version 21.0 (IBM Corp., Armonk, NY, USA). A p<0.05 was considered significant for all tests. Descriptive analysis was used for all variables. Categorical variables were displayed as frequencies and percentages, continuous variables were represented as medians. The receiver operating characteristic (ROC) analysis was applied to determine the optimal cut-off values of pre- CRT NLR and post-CRT NLR for prognostic prediction of good pathological response to neoadjuvant CRT and survival. The relationship between the NLR and the clinicopathological characteristics were compared using the chi-square test or Fisher's exact test for categorical variables and with Student's t-test for continuous variables. Logistic regression analysis was used to analyze the significant factors related to response to neoadjuvant CRT. The patients" survival data were evaluated using the Kaplan- Meier method and the differences were compared using log-rank statistics. Univariate and multivariate analyses to identify prognostic predictors were performed using Cox proportional hazard regression models.
The ROC analysis revealed favorable cut-off values
of 2.87 (area under the curve [AUC]: 0.709, sensitivity 66%, specificity 65%, p=0.015) for pre-CRT
NLR associated with good pathological response and
8.68 (AUC: 0.678, sensitivity 61%, specificity 72%,
p=0.035) for post-CRT NLR predicting survival, as
shown in Figure
ROC: Receiver operating characteristic.
Logistic regression analysis showed that patients
in the low pre-CRT NLR group had better outcomes
in terms of good pathological response compared
to the high pre-CRT NLR group (OR 4.15, 95% CI
1.23-13.76, p=0.021) (Table
The 5-year OS was 65.7% for all patients. The 5-year
OS in patients low and high pre-CRT NLR groups were
52.9% and 68.4% (p=0.757). An elevated post-CRT
NLR was a significantly poor prognostic factor for OS,
with 5-year OS rates of 74.4% and 46.6% for low and
high post-CRT NLR groups (p=0.006) (Fig.
The 5-year DFS was 57.6% for all group. The 5-year
DFS rates did not differ significantly between the
low and high pre-CRT NLR groups (57.7% vs. 58%,
p=0.860). Low post-CRT NLR group showed a significantly
improved 5-year DFS rate compared to high
post-CRT NLR group (71.9% vs. 35.3%, p=0.018) (Fig.
The 5-year LRRFS was 62.8% for all patients. The
pre-CRT NLR was statistically insignificant for LR-RFS, with 5-year LRRFS rates of 64.7% and 62.3% for
low and high pre-CRT NLR groups (p=0.927). The
5-year LRRFS rate was significantly better in low post-
CRT NLR group (78.1% vs. 40.8%, p=0.006) (Fig.
The strengths of this study are as follows. First of all, the patients received treatment in a single center and their treatment was planned according to the same guidelines. Therefore, patient management did not differ between patients included in the study and biased results were avoided. Although the sample size was small, to obtain accurate results, we analyzed a highly selected proportion of patients undergoing surgical treatment with known pathology results. In addition, patients who did not have blood tests within the specified date ranges were excluded from the study in order to obtain the most reliable results. Finally, in order to make the study more deterministic, two different cutoff values that could be predictive of both good pathologic response to neoadjuvant CRT and survival were obtained separately from ROC analysis.
It is well known that the NLR is one of the most widely used indices as an indicator of immune inflammation, with its high prognostic ability to predict survival as it reflects host immune activity.[4,5] Previous studies have explored the prognostic utility of NLR in various solid tumors as well as colorectal tumors.[7,8] Therefore, we have the knowledge that worse survival was observed in relation to higher NLR, confirmed by several published data. However, there is uncertainty about the effect of NLR on oncologic outcomes in patients undergoing neoadjuvant CRT for rectal cancer with known conflicting results. Dong et al.[9] performed a meta-analysis of seven studies including data from 959 patients treated with CRT/surgery or surgery, results demonstrated that high NLR was significantly related with worse OS, disease-free survival and recurrence- free survival. In contrast, a meta-analysis of 8 centers including 1237 patients compiled by Dudani et al.[10] failed to demonstrate the prognostic effect of NLR on survival. However, the following confounders should be noted when interpreting latter metaanalysis, which included only Canadian data, since the threshold value for NLR was not obtained for the patient population, the threshold value previously suggested by Templeton for various solid tumors was used instead of the value of their own data;[4] blood tests were taken over a wide period of time, 4 weeks before and 2 weeks after the start of CRT, were also accepted. It should be kept in mind that the indices may change, especially with the initiation of CRT. In our study, we evaluated baseline and post-treatment NLR, our results showed that post-CRT NLR was associated with OS, DFS, LRRFS rates, but pre-CRT NLR was not prognostic for survival by ROC analysis.
The link between systemic inflammation indices and tumor development has been demonstrated in many studies, but the primary goal was often to investigate the relationship between NLR and survival outcomes.[11,12] In particular, prediction of response assessment to neoadjuvant treatment according to NLR was beyond the scope. In the last decade, a limited number of studies examining this issue have been presented to the literature. [13-17] In this regard, the first data were obtained from the study presented by Krauthamer et al.[13] They reported that patients with low NLR had better complete response rates, but this relationship was only demonstrated in stage 3 patients. In another study that followed, NLR was found to be an independent predictive factor for tumor response and survival.[14] On the contrary, Shen et al.[15] reported no difference was found between the NLR groups in terms of tumor response. The reason why they could not obtain significant results may be that they could not determine the threshold value in the ROC analysis for their data and a cut-off value was selected from previous studies for analysis. In the other two studies, in which treatment response was evaluated with pre-and post-treatment NLR values, pre-treatment NLR was found to be predictive on tumor response, but this correlation with post-treatment NLR could not be demonstrated.[ 16,17] These two studies support our study with similar results.
According to previous data, increased T stage, lymph node-positive disease, presence of LVI, residual disease microscopically or macroscopically after surgery, poor pathological response to neoadjuvant therapy, are some of the unfavorable factors known to be prognostic for survival and recurrent disease.[18,19] Consistent with these data, we found that among these factors, high T stage, pathological node-positive disease, presence of LVI, and poor pathological response to neoadjuvant therapy were associated with the high pre-CRT NLR group. In addition, we found that increased T stage and high pre-CRT NLR were associated with a lower probability of achieving a good pathological response to neoadjuvant therapy. These findings may indicate that high NLR shares the same denominator with known poor prognostic factors.
Nowadays, although it is not routinely recommended, it is included in the guidelines that surgical treatment may not be applied in some special cases with good response to therapy. Neoadjuvant therapy or total neoadjuvant therapy are the mainstays of this non-surgical approach. After clinicians evaluate the treatment response clinically with a detailed evaluation including rectal examination, rectal imaging, and endoscopic examinations instead of post-surgical pathological examination, "watch and wait" strategy can be applied in experienced centers in patients with clinically complete response.[20] However, clinical evaluation has some limitations due to the shortcomings of each of the above-mentioned methods due to difficulties in the post-treatment setting.[21] Since patients cannot be evaluated with full accuracy by clinical evaluation, it may result in downstaging of patients compared to pathological evaluation. In this context, systemic inflammation indices can contribute to post-treatment assessment regarding the creation of personalized treatment strategies, due to the prediction of response assessment and prognostic impact on survival.
Limitations of the Study
Some limitations of this study must be acknowledged,
one of which is the small sample size obtained from a
single-center study. This small sample size may also be responsible for our failure to demonstrate a significant
relation between the well-known prognostic factors
such as pCR and patient survival. Furthermore, there
is the possibility of selection bias due to its retrospective
design. Further analysis of a large population supported
by a multicenter study is required to more accurately
confirm the predictive value of NLR.
Peer-review: Externally peer-reviewed.
Conflict of Interest: All authors declared no conflict of interest.
Ethics Committee Approval: The study was approved by The University of Health Sciences, Samsun Training and Research Hospital Non-Interventional Clinical Research Ethics Committee (No: 2018/1/10, Date: 09/01/2018).
Financial Support: This study has received no financial support.
Authorship contributions: Concept - E.D.S., Y.K., E.O.; Design - E.D.S., Y.K., N.Ş., Y.G.; Supervision - E.D.S, S.A.A.; Funding - None; Materials - E.D.S., Y.K., E.O., N.Ş., B.K.Y., İ.M.Y.; Data collection and/or processing - E.D.S., E.O., N.Ş., B.K.Y., İ.M.Y.; Data analysis and/or interpretation ? E.D.S., B.K.Y., İ.M.Y., S.A.A., Y.G.; Literature search ? E.D.S., E.O., N.Ş., B.K.Y., İ.M.Y.; Writing - E.D.S., S.A.A.; Critical review - E.D.S., S.A.A., Y.G.
