Lymphocyte to C-reactive protein ratio predicts long-term outcomes for patients with lower rectal cancer

Backgrounds The lymphocyte to C-reactive protein (CRP) ratio (LCR) is an indicator of systemic inflammation and host–tumor cell interactions. The aim of this study was to investigate the prognostic significance of LCR in lower rectal cancer patients who received preoperative chemo-radiotherapy (CRT). Methods Forty-eight patients with lower rectal cancer who underwent CRT followed by curative surgery were enrolled in this study. Routine blood examinations were performed before and after CRT were used to calculate pre-CRT LCR and post-CRT LCR. The median LCR was used to stratify patients into low and high LCR groups for analysis. The correlation between pre- and post-CRT LCR and clinical outcomes was retrospectively investigated. Results The pre-CRT LCR was significantly higher than the post-CRT LCR (11,765 and 6780, respectively, P < 0.05). The 5-year overall survival rate was significantly higher for patients with high post-CRT LCR compared with low post-CRT LCR (90.6% and 65.5%, respectively, P < 0.05). In univariate analysis, post-CRT LCR, post-CRT neutrophil to lymphocyte ratio, and fStage were significant prognostic factors for overall survival. In multivariate analysis, post-CRT LCR, but not other clinicopathological factors or prognostic indexes, was a significant prognostic factor for overall survival (P < 0.05). Conclusions Post-CRT LCR could be a prognostic biomarker for patients with lower rectal cancer.

Among the various prognostic scores investigated, preoperative LCR has been identified as an independent prognostic biomarker in patients with colorectal cancer (CRC) [10]. LCR is easily measurable from routine laboratory data and is a reflection of the status of the host anti-tumor immune and systemic inflammatory responses [10]. To date, however, only a few reports have considered the prognostic significance of LCR, including the utility of pre-and post-CRT LCR, in patients with cancers of the gastrointestinal tract [10,[14][15][16]. Therefore, the aim of the present study was to investigate the prognostic significance of pre-and post-CRT LCR in patients with lower RC who underwent preoperative CRT.

Patients and study design
A total of 48 patients with lower RC who underwent CRT followed by curative resection at Tokushima University Hospital between 2004 and 2012 were included in this retrospective study. The protocol was approved by the Ethics Committee of Tokushima University (approval no. 3215-1) and was conducted according to the provisions of the Declaration of Helsinki. All patients provided informed consent for the use of their data. Table 1 shows the clinicopathological characteristics of 48 patients. Clinical data were obtained from medical records and included demographic information, laboratory data, tumor properties, staging, and treatment modalities. Routine laboratory tests were performed on the first day of CRT and within 1 week after the final day of CRT.
Eighteen patients underwent low anterior resection, 10 patients underwent intersphincteric resection, 11 patients underwent abdominoperineal resection, and 2 patients underwent trans-anal local resection. Pathological responses were evaluated by pathologists according to the Japanese Classification of Colorectal Carcinoma. Patients were followed up postoperatively for at least 5 years. Recurrence of primary RC was evaluated by tumor marker levels and computed tomography.

LCR calculation
LCR was calculated as the ratio of TLC (per μL) to serum CRP (mg/dL) (10). The median LCR (11,765 pre-CRT and 6780 post-CRT) was used as the cutoff for stratification of patients into low and high pre-CRT LCR and post-CRT LCR groups. Clinicopathological parameters, OS, and disease-free survival (DFS) were evaluated among the four groups.

Results
Changes in TLC, serum CRP, and LCR following CRT are shown in Fig. 1. TLC was significantly lower post-CRT compared with pre-CRT (810/μL and 1662/μL, respectively, P < 0.05; Fig. 1A), whereas serum CRP did not change significantly (0.14 mg/dL and 0.12 mg/dl, respectively, Fig. 1B). Consequently, the post-CRT LCR was also significantly lower than the pre-CRT LCR, with median values of 6780 and 11,765, respectively (Fig. 1C, P < 0.05). LCR was increased in 13 patients and decreased in 35 patients after CRT (Fig. 1C).
Associations between pre-CRT and post-CRT LCR and clinicopathological parameters in patients assigned to low and high LCR groups are shown in Tables 2 and 3. A significant correlation between pre-CRT LCR and clinicopathological characteristic was found only for CRP (Table 2), whereas CRP, TLC, and pre-CRT LCR were significantly correlated with post-CRT LCR ( Table 3). The prognostic significance of pre-CRT LCR and post-CRT LCR is shown in Fig. 2. Patients in the low pre-CRT LCR group had poorer 5-year OS compared with the high pre-CRT LCR group, albeit not significantly (70.3% and 80.1%, respectively, P = 0.14; Fig. 2A). In contrast, patients in the low post-CRT LCR group had significantly poorer 5-year OS than the high post-CRT LCR group (65.5% and 90.6%, respectively, P < 0.05; Fig. 2C). Notably, there were no significant differences in DFS between patients with high and low pre-CRT LCR (Fig. 2B) or post-CRT LCR (Fig. 2D).
Univariate analysis revealed that fStage, post-CRT NLR, and post-CRT LCR were significant prognostic factors for OS. Multivariate analysis demonstrated that CA19-9 level and post-CRT LCR were independent prognostic factors for OS ( Table 4). The sites of RC recurrence were not significantly different between the high and low post-CRT LCR groups, whereas a high post-CRT LCR was significantly associated with surgery as a curative treatment (Table 5, P < 0.05).

Discussion
In the current study, we retrospectively analyzed the significance of LCR as a prognostic marker for patients with lower RC who received preoperative CRT. LCR is of great potential interest as a prognostic marker because it reflects the systemic inflammatory and immune responses and can be readily calculated from routinely  Patients were stratified using the median LCR. WBC white blood cell, TLC total lymphocyte count, Alb albumin, CRP C-reactive protein, CEA carcinoembryonic antigen, LCR lymphocyte-CRP ratio, tub1 well-differentiated tubular adenocarcinoma, tub2 moderately differentiated tubular adenocarcinoma, S-1 tegafur-gimeracil-oteracil, UFT tegafur-uracil, 5-FU 5-fluorouracil, CRT chemoradiotherapy, LAR low anterior resection, ISR intersphincteric resection, APR abdominoperineal resection WBC white blood cell, TLC total lymphocyte count, Alb albumin, CRP C-reactive protein, CEA carcinoembryonic antigen, LCR lymphocyte-CRP ratio, tub1 welldifferentiated tubular adenocarcinoma, tub2 moderately differentiated tubular adenocarcinoma, S-1 tegafur-gimeracil-oteracil, UFT tegafur-uracil, 5-FU 5fluorouracil, CRT chemo-radiotherapy, LAR low anterior resection, ISR intersphincteric resection, APR abdominoperineal resection collected laboratory data. We identified LCR as a reliable biomarker of prognosis in our patient cohort, with low post-CRT LCR being significantly correlated with poor prognosis in both univariate and multivariate analysis. We also evaluated the potential prognostic significance of PNI and NLR, which are composed of combinations of neutrophil, lymphocyte, and platelet counts, and serum albumin and CRP levels, in univariate and multivariate analysis; however, neither of these scores was an independent prognostic factor for OS in our cohort. A paradigm shift in cancer treatment has resulted in interactions between the tumor and immune system becoming a major therapeutic target [18,19]. In particular, multiple lymphocyte subsets play crucial roles in antitumor immunity, and many immune checkpoint inhibitors targeting T lymphocytes are currently in use for the treatment of various cancers. Accordingly, cancer patients with high TLC generally have a better prognosis [20,21]. Within the tumor microenvironment, tumor cells may also interact with a variety of other cells, such as myeloid-derived suppressor cells, tumor-associated macrophages, mast cells, dendritic cells, and cancerassociated fibroblasts in the tumor stroma. Interactions between tumor cells and host cells stimulate not only For low/high categories, patients were stratified using the median LCR. WBC white blood cell, TLC total lymphocyte count, Alb albumin, CRP C-reactive protein, CEA carcinoembryonic antigen, tub1 well-differentiated tubular adenocarcinoma, tub2 moderately differentiated tubular adenocarcinoma, S-1 tegafur-gimeracil-oteracil, UFT tegafur-uracil, 5-FU 5-fluorouracil, CRT chemo-radiotherapy, LAR low anterior resection, ISR intersphincteric resection, APR abdominoperineal resection, TLC total lymphocyte count, LCR lymphocyte-CRP ratio, NLR neutrophil-lymphocyte ratio, PNI prognostic nutritional index Patients were stratified using the median LCR. LN lymph node, BSC best supportive care, LCR lymphocyte-CRP ratio, NS not significant tumor growth but also angiogenesis and metastasis [22][23][24]. Tumor-infiltrating lymphocytes (TILs) are key markers of the anti-tumor immune response, and positive associations have been described between the abundance of TILs and prognosis of patients with various cancers [25][26][27][28][29]. Kitayama et al. reported that the number of peripheral blood lymphocytes correlated significantly with the rate of complete response to RT of patients with advanced RC, and they considered that lymphocyte-mediated responses may therefore play a pivotal role in the effects of RT [29]. Furthermore, Lee et al. suggested that peripheral lymphocyte counts correlated with TILs in breast cancer and that TLC might serve as a surrogate marker of TILs [30].
Local and systemic inflammatory responses are thought to promote cancer through several mechanisms [31,32], including promotion of tumor cell growth and angiogenesis, and inhibition of DNA damage and apoptosis via inflammatory cytokines and chemokines [33,34]. Moreover, several inflammatory markers may act as predictors of the therapeutic response [35][36][37]. For example, CRP is a prognostic indicator for several types of solid tumors, including CRC [35][36][37].
Okugawa et al. first identified LCR as a promising biomarker for CRC in their analysis of several candidate prognostic biomarkers that included neutrophil count, TLC, platelet count, albumin, and CRP [10]. The significance of LCR has also been demonstrated in patients with esophageal, gastric, and rectal cancer who received CRT [14][15][16].
Our results in the current study show that high post-CRT LCR may be a predictive marker of better prognosis for patients with RC undergoing CRT followed by curative surgery. The high post-CRT LCR in our cohort was largely a reflection of post-CRT maintenance of TLC with a small, but insignificant, increase in CRP level, and it might therefore be indicative of strong antitumor immunity and a mild pro-inflammatory effect on the microenvironment. Interestingly, although elevated post-CRT LCR predicted favorable OS, there was no significant association between post-CRT LCR and DFS. A high post-CRT LCR was most common among patients who received curative surgery, whereas a low post-CRT LCR was more common among patients who received chemotherapy as a palliative treatment. Moreover, the time to treatment failure (recurrence) tended to be longer for high post-CRT LCR group than the low post-CRT LCR group (data not shown), which may be due to a stronger overall anti-tumor immune response in patients with high post-CRT LCR. Accordingly, patients with high post-CRT LCR might be considered for adjuvant treatment to prevent recurrence.
There are some limitations to our study. This was a single-center retrospective study and the results may not extrapolate to other environments. In addition, the sample size was small. Multicenter studies with larger cohorts will be needed to overcome these limitations, validate the results of this study, and identify the optimal cutoff value for the LCR for further studies of its prognostic value.
In conclusion, the findings of the present study suggest that the LCR could be an important predictive biomarker for the prognosis of patients with lower RC who undergo CRT followed by curative surgery.