Objectives To examine the prognostic impact of a node-specific staging system for stage IB cervical cancer based on the 2018 FIGO classifications and to assess the efficacy of postoperative adjuvant therapy for nodal metastasis in stage IIIC cervical cancer.

Methods This is a society-based retrospective observational study in Japan, examining 16,539 women with stage IB1 cervical cancer who underwent primary surgical treatment from 2004–2015. Associations between nodal metastasis and cause-specific survival (CSS) and postoperative adjuvant therapy and CSS were examined according to histology type (Squamous cell carcinoma [SCC] n=10,315 and non-SCC n=6,224).

Results The nodal metastasis rate for SCC was higher than that for non-SCC (10.7% versus 8.3%, P<0.001). In a multivariable analysis, the impact of pelvic nodal metastasis on CSS for non-SCC tumors (adjusted-hazard ratio [HR] 2.89, 95% confidence interval [CI] 1.93–4.31) was larger than for SCC tumors (adjusted-HR, 1.84, 95%CI 1.38–2.44). A propensity score matching analysis showed that women with pelvic nodal metastases had significantly lower CSS rates with non-SCC tumors than with SCC tumors (5-year CSS, 75.4% versus 90.3%, P<0.001). Postoperative chemotherapy improved CSS for women with pelvic nodal metastases (HR 0.65, 95%CI 0.44–0.95, P=0.024); however, the efficacy of postoperative chemotherapy on CSS for these was differ according to histology type.

Conclusions For stage IB1 cervical cancer, the node-specific staging system in the 2018 FIGO cervical cancer classification is more applicable to non-SCC tumors than to SCC tumors. The survival benefits of postoperative adjuvant therapy for IIIC1 patients likely differ between SCC and non-SCC tumors.