4.1. Limitations
tumor
TUMOR, COMPLICATIONS
First, the SEER database only provides a collection of patients in the United States, and the nomogram constructed in this study has not been demonstrated to be applicable to other regions. Meanwhile, this nomogram was only validated by dividing the total cases into training group and validation group. Therefore, further external validation of the nomogram in totally different independent clinical cases, especially from different countries, is needed to obtain an unbiased estimation. Second, certain factors that might associate with survival were not incorporated into the study because of insufficient information in the SEER database. For example, many potential tumor biomarkers, including HE4 protein and serum mesothelin, were not included in the analysis. The detailed chemotherapy regimens, information on targeted drugs, complications, and other information with important significance for the prognosis of EOC were also not available in the SEER database. Third, our nomogram was established on retrospective data which has an inevitable inherent bias. Also, this study may have selection bias because only patients with specific clinical information were included. Finally, it should be noted that this study had a relatively small sample size of only 454 patients. This limitation in sample size may account for the moderate predictive power observed in our model.