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

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

Methods: 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.

Results: 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).

Conclusions: 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.