It is well accepted that LMR as one of the immunoinflammatory markers was playing an important role in immune surveillance and tumor progression. Previously published data had demonstrated the correlation between survival and LMR from different points in time, especially in the preoperative setting. However, there were no reports concerning the prognostic role of the kinetics of this biomarker during treatment. Indeed, this is the first study to investigate the prognostic value of LMR and its kinetic after gastrectomy and adjuvant chemotherapy in patients with LAGC. We found that LMR increased after treatment was an independent favorable factor of prognosis. In addition, patients with intestinal Lauren classification or well-differentiated might be more susceptible to enhance immunity after treatment.
As the basis for the adaptive and innate immune system, lymphocytes participate and enhance immune-surveillance, thereby mediating cytotoxic cell and inhibiting tumor cell proliferation, invasion, and metastasis [20]. It has been reported that the presence of tumor-infiltrating lymphocytes was associated with improving the prognosis in a variety of tumors, possibly owing to tumor-infiltrating, lymphocyte-induced, and anti-tumor activity as well as angiogenesis [21]. Therefore, lymphocytopenia weakens the immune response and represents a decrease of anti-tumor ability and a poor outcome in patients with cancer. Inversely, the circulating monocytes may contribute to tumor growth and inhibit immunosurveillance according to the previous finding [22]. Furthermore, tumor-associated macrophages derived from circulating monocytes have been proven to be associated with tumor metastasis, enhanced angiogenesis, and poor outcome [23]. Thus, LMR, which is calculated based on the values of ALC and AMC, can amplify the ability of ALC and AMC to reflect the immune response and play an important role in the prognosis of GC.
Several studies have determined the prognosis value of LMR in the preoperative and postoperative setting [13, 24–26].However, there was an important limitation that the cut-off value for LMR differed among those researches and, thus limited patient stratification. In addition to this, the outcome may be similar even if the patients were at different groups according to pLMR. In our study, the optimal cutoff value for pLMR is 4.53, and the 5-year OS rate between patients in HL group and LG group are indiscrimination. Previous studies focused on the dynamic changes in terms of the LMR after treatment showed that compared with the pretreatment LMR, the LMR elevated at 4 weeks after the start of nivolumab monotherapy was significantly associated with a prolonger progression-free survival and OS in non-small-cell lung cancer [27]. Moreover, LMR increased more than 1.8 from day 15 to day 100 in patients with Hodgkin Lymphoma who underwent autologous stem cell transplantation was correlated with a lower risk of relapse [28]. In this study, we found that increased cLMR was a favorable prognostic factor for A GC. Although the prognostic accuracy of cLMR was not as well as pLMR, the combination of cLMR could further assist pLMR in identifying outcome and selecting the patients who should receive individualized treatment. Additionally, cLMR was an independent prognostic factor and an increased cLMR was associated with a well histological type or intestinal Lauren classification. These data support the notion that cLMR, which reflected a dynamic reaction of immune response caused by treatment and tumor load, was also a meaning measurement. Therefore, we developed a novel prognostic score, called ICS, based on the combination of pLMR and cLMR, and found that the ICS was also an independent prognostic factor for patients with LAGC. Moreover, as an integrated indicator, the clinical value, discrimination and prognostic accuracy of ICS were significantly better than that of pLMR and cLMR. Thus, we recommended that patients with lower ICS should reexamine regularly and try to receive some molecular targeted agents.
To date, the most important and common predictive systems for GC are the AJCC TNM staging system, which is based on the depth of tumor invasion (T), the number of lymph node metastasis (N), and the distant metastases (M)[15]. However, due to the variety of patient prognosis, it might be ambiguous for patient selection solely depending on the TMM classification. To assist with clinical practice and decision making, a nomogram, currently an accurate and discriminatory tool for predicting prognosis among patients with cancer [29], was built by incorporating ICS into CEA and TNM staging. It is essential to validate the nomogram to avoid overfitting of the model and determine generalizability [30]. In this study, the calibration plots for 3-year and 5-year survival showed a favorable agreement between prediction and actual obversion in the internal validation, which guarantees the reliability of the constructed nomogram. Moreover, the nomogram exhibited better discrimination power and accuracy than that of non-ICS or pLMR based nomogram. Therefore, in clinical practice, the ICS can be used as a supplement to the TNM staging system to identify high-risk subgroups of patients, to assess the individual clinical outcome, and to provide a basis for guiding follow-up and treatment.
Our study does have some limitations and deficiencies. First, we lacked the data to examine all patients at all time points during treatment. Second, this study with a retrospective nature was performed in a single center, that inevitably led to potential biases and a relatively small sample size. However, the sample size of this article is sufficient to effectively show the prognosis value of LMR kinetics on survival. Moreover, due to the patients were consecutively enrolled, some patients had a follow-up period less than five years and no outcome was observed, which may have an impact on the results of the survival analysis. Finally, because the ICS in our nomogram is calculated based on LMR after three cycles of chemotherapy, so it doesn’t apply to the prediction of outcomes in the initial three months after surgery. Future studies will need to elucidate the mechanism of changes in immune status of GC patients with different tumor stages after surgery or chemotherapy to deduce whether cLMR can better stratify patients for additional treatment.