A prognostic nomogram based on lymph node ratio for postoperative vulvar squamous cell carcinoma from the Surveillance, Epidemiology, and End Results database: a retrospective cohort study

Background

Vulvar carcinoma is a rare gynecological malignancy. The most commonly used staging system for vulvar cancer is the 2009 International Federation of Gynecology and Obstetrics (FIGO) staging system. Nevertheless, it does not incorporate many indispensable prognostic parameters, which prominently influence vulvar cancer patient survival. Thus, the development of a prediction model for evaluating survival prognosis in postoperative vulvar squamous cell cancer patients is of vital importance.

Methods

Data from 2,166 patients with pathologically confirmed diagnosis of vulvar squamous cell carcinoma from 2004 to 2015 were acquired from the Surveillance, Epidemiology, and End Results (SEER) database. Thirty percent of the patients were randomly assigned to the validation group, and the remainder were used to develop the nomogram. Parameters that significantly correlated with overall survival (OS) were used to create the nomogram. Concordance index (C-index), calibration curve, and decision curve analysis (DCA) were used to assess the predictive accuracy and discriminability of the nomogram model. Additionally, the C-index and DCA of the nomogram and the FIGO staging system were compared.

Results

Following multivariate analysis of the training cohort, independent factors for OS, including race, age at diagnosis, marital status, FIGO stage, tumor diameter, and lymph node ratio (LNR), were included in the nomogram model. The calibration curve indicated a high correlation between the nomogram-predicted and observed survival probability. The C-index of the nomogram in the training cohort was 0.772 (95% CI: 0.752–0.792), statistically superior to the C-index value of the FIGO staging system (0.676, 95% CI: 0.654–0.698). In DCA, compared to the FIGO staging system, this nomogram showed a greater net benefit and a wider range of threshold probability. Results were verified by an internal validation cohort.

Conclusions

Our nomogram, based on LNR, showed superior prognostic predictive accuracy compared with the FIGO staging system for predicting OS in postoperative vulvar squamous cell carcinoma patients.

Lymph node ratio in inguinal lymphadenectomy for squamous cell vulvar cancer: Results from the AGO-CaRE-1 study

OBJECTIVE

Lymph node ratio (LNR) can predict treatment outcome and prognosis in patients with solid tumors. Aim of the present analysis was to confirm the concept of using LNR for assessing outcome in patients with vulvar cancer after surgery with inguinal lymphadenectomy in a large multicenter project.

METHODS

The AGO-CaRE-1 study multicenter database was used for analysis. LNR was defined as ratio of number of positive lymph nodes (LN) to the number of resected. Previously established LNR risk groups were used to stratify patients. LNR was investigated with respect to clinical parameters. Univariate and multivariable survival analyses were performed to assess the value of LNR in order to predict overall (OS) and progression-free (PFS) survival.

RESULTS

In total, 1047 patients treated with surgery including inguinal lymph node resection for squamous cell carcinoma of the vulva were identified from the database. Of these, 370 (35.3%) were found to have positive inguinal LN. In total, 677 (64.7%) had a LNR of 0% (N0), 255 (24.4%) a LNR of >0% < 20%, and 115 (11%) a LNR of ≥20%. Patients with higher LNR were found to have larger tumor size (P < .001), advanced tumor stage (P < .001), high tumor grade (P < .001), and deep stromal invasion (P < .001), more frequently. Three-year PFS rates were 75.7%, 44.2%, and 23.1% and three-year OS rates were 89.7%, 65.4%, and 41.9%, in patients with LNRs 0%, >0% < 20%, and ≥20%, respectively (P < .001, P < .001). On multivariable analyses LNR (HR 7.75, 95%-CI 4.01-14.98, P < .001), FIGO stage (HR 1.41, 95%-CI 1.18-1.69, P < .001), and patient's performance status (HR 1.59, 95%-CI 1.39-1.82, P < .001), were associated with PFS. In addition, LNR (HR 12.74, 95%-CI 5.64-28.78, P < .001), and performance status (HR 1.72, 95%-CI 1.44-2.07, P < .001) were also the only two parameters independently associated with OS. LNR generally showed stronger correlation than number of affected LN when comparing the two different multivariable models.

CONCLUSIONS

In women with vulvar cancer LNR appears to be a consistent, independent prognostic parameter for both PFS and OS and allows patient stratification into three distinct risk groups. In survival analyses, LNR outperformed nodal status and number of positive nodes.