Lymph node metastasis in ovarian cancer: difference between serous and non-serous primary tumors

To investigate the lymph node sites most susceptible to involvement relative to primary tumor histology in ovarian cancer.

The locations of metastatic lymph nodes were investigated in 208 patients with primary ovarian cancer who underwent systemic lymphadenectomy covering both the pelvic and para-aortic regions.

Lymph node metastasis was present in 12.8% (20/156) of patients with stage I (pT1M0), 48.6% (18/37) with stage II (pT2M0), and 60% (9/15) with stage III (pT3M0) disease, thus in 22.6% (47/208) of all study patients. Isolated para-aortic nodal involvement was present in 23.3% (14/60) of patients with serous tumor and 4.1% (6/148) of those with non-serous tumor (P = 0.00002). In an analysis of 35 positive nodes from 25 patients with up to 3 positive nodes, 86.4% (19/22) of metastatic lymph nodes from patients with serous tumor were found in the para-aortic region, with 14 positive nodes located above the inferior mesenteric artery (IMA) and 5 below it, whereas metastasis to para-aortic lymph nodes accounted for 53.8% (7/13) of metastatic lymph nodes from patients with non-serous tumor (P = 0.0334).

The locations of metastatic lymph nodes in ovarian cancer depend upon the histologic type of the primary cancer. In cases of serous tumor, the para-aortic region, particularly above the IMA, is the prime site for the earliest lymph node metastasis. However, the likelihood of pelvic node involvement is almost equal to that of para-aortic node involvement in cases of non-serous tumor.