Does tumor grade influence the rate of lymph node metastasis in apparent early stage ovarian cancer?

Abstract

To evaluate the prevalence of regional lymph node (LN) metastasis in patients with non-clear cell epithelial ovarian cancer apparently confined to the ovary, stratified by tumor grade. The National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database was accessed (1988-2014). We identified patients with epithelial ovarian carcinoma of serous, endometrioid and mucinous histology apparently confined to the ovary who underwent extensive lymphadenectomy (defined as at least 20 lymph nodes removed). Demographics, tumor histology, grade and lymph node status were collected. Comparisons were made with Chi square and Mann-Whitney U tests. A total of 1242 women met the inclusion criteria. Endometrioid adenocarcinoma was the most common histology (564 patients (45.4%)) while 443 (35.7%) and 235 (18.9%) patients had serous, and mucinous adenocarcinoma, respectively. The rate of LN metastasis in low-grade serous was 9.0% (6/67) vs. 14.4% (54/376) in high-grade serous histology (OR, 1.71, 95% CI 0.70, 4.14, p = 0.24). In patients with low-grade endometrioid tumors, the rate of LN metastasis was 1.7% (7/407) vs. 5.1% (8/157) observed in those with high-grade tumors (OR: 3.07, 95% CI 1.09, 8.61, p = 0.033). Lastly, the rate of LN metastasis in mucinous histology was 1.7% (3/177) in low-grade vs. 8.6% (5/58) in high-grade tumors (OR: 5.47, 95% CI 1.27, 23.66, p = 0.024). Regional LN metastasis in apparent stage I low-grade mucinous and endometrioid ovarian tumors is infrequent.