Systematic pelvic lymphadenectomy is an important part of surgical treatment for FIGO Stage IA2 to IIA2 cervical cancer. However, it remains an unresolved issue that a minimum number of nodes should be required to consider the lymphadenectomy as adequate. Prapaporn et al. suggested that more than 10 nodes should be removed for standard pelvic lymphadenectomy . Similarly, removal of more than 11 pelvic lymph nodes was suggested as a quality indicator for pelvic lymphadenectomy in an EORTC-GCG study . In this study, the number of pelvic lymph nodes removed ranged from 11 to 67, which meet the qualification of previous studies. Moreover, the status of regional lymph nodes is known to be an important indicator for the prognosis of cervical cancer patients .
Nevertheless, what remains controversial is if cervical cancer patients who have the same number of positive nodes but different numbers of removed pelvic nodes have similar overall survival. Several studies showed that positive nodal ratio was an independent prognostic parameter for OS of malignant solid tumors, including gastric cancer , colon cancer , esophageal cancer . As for gynecologic malignant diseases, previous studies demonstrated the ratio of positive lymph node provides a significant prognostic value in epithelial ovarian cancer  and endometrial cancer [18, 19]. However, Metindir et al.  and Polterauer et al.  drew diametrically opposite conclusions on the impact of RPL on the prognosis of cervical cancer patients. In this study, we selected cutoff values of 0%, 5% and 20% for further analysis. Survival analysis revealed that greater RPL values correlated with lower 5-YSR. Moreover, multivariate analysis showed that RPL was an important independent indicator for postoperative cervical cancer patients.
Recently, studies about NLNs associated with postoperative survival prediction for cancer patients caused more and more attention. NLNs dissection is a surrogate marker related to the quality of surgery; it reflects the extent of LN dissection. Previous studies had demonstrated the NLNs count is a marker of both the efficacy of lymph node evaluation and patient prognosis with some carcinoma. Schwarz et al.  reported that higher NLN counts were correlated with longer survival of gastric cancer patients after curative resection. Johnson et al.  showed that there was a marked decrease in disease-specific mortality as the number of negative nodes increased in patients with stage IIIB and IIIC colon cancer. In this study, we speculated that it is crucial for the total collected lymph nodes to comprise NLNs count, which is the basic guarantee for cervical cancer after RHPL. We identified that 5-YSR became higher as the NLNs count increased. This may be because NLNs have reduced potential for micro-metastasis. Theoretically, the higher the NLNs count, the more likely it is that resection will be optimal and not leave any potential metastasis behind.
Standard pathologic examination of lymph nodes is based on hematoxylin-eosin staining. Retrospective studies report that the incidence of micro-metastasis is between 1.5% and 15%, depending on the technique used to evaluate lymph node status . The International Ludwig Breast Cancer group examined lymph nodes from 736 patients with negative lymph nodes and found an occult metastasis rate of 7% using serial sectioning alone and 20% using cytokeratin immunohistochemistry . More importantly, they found that occult metastases detected by either method were associated with a significant decrease in disease-free and overall survival [22, 23]. By using immunohistochemistry, Margrit et al. identified 8% of cervical cancer patients with lymph node micro-metastasis not initially identified by hematoxylin-eosin analysis . Their findings are consistent with those of Lentz et al., who found micro-metastases in 14% of patients with stage IA1–IIA cervical cancer with histologically negative lymph nodes using anti-cytokeratin immunohistochemical staining . Although we have not used immunohistochemical antibodies to detect micro-metastasis within NLNs, we demonstrated that increasing NLNs count could greatly improve the 5-YSR of cervical cancer patients. Therefore, we concluded that the higher the NLNs count, the higher the probability that micro-metastasis within lymph nodes will be found.
Additionally, we found advanced stage, low histologic grade and high RPL were independent markers of poor prgnosis for cervical cancer patients, which partially was consistent with previous study .