Implications of para-aortic lymph node metastasis in patients with endometrial cancer without pelvic lymph node metastasis

OBJECTIVE The aim of this study was to confirm the incidence and implications of a lymphatic spread pattern involving para-aortic lymph node (PAN) metastasis in the absence of pelvic lymph node (PLN) metastasis in patients with endometrial cancer. METHODS We carried out a retrospective chart review of 380 patients with endometrial cancer treated by surgery including PLN dissection and PAN dissection at Hokkaido Cancer Center between 2003 and 2016. We determined the probability of PAN metastasis in patients without PLN metastasis and investigated survival outcomes of PLN-PAN+ patients. RESULTS The median numbers of PLN and PAN removed at surgery were 41 (range: 11-107) and 16 (range: 1-65), respectively. Sixty-four patients (16.8%) had lymph node metastasis, including 39 (10.3%) with PAN metastasis. The most frequent lymphatic spread pattern was PLN+PAN+ (7.9%), followed by PLN+PAN- (6.6%), and PLN-PAN+ (2.4%). The probability of PAN metastasis in patients without PLN metastasis was 2.8% (9/325). The 5-year overall survival rates were 96.5% in PLN-PAN-, 77.6% in PLN+PAN-, 63.4% in PLN+PAN+, and 53.6% in PLN-PAN+ patients. CONCLUSION The likelihood of PAN metastasis in endometrial cancer patients without PLN metastasis is not negligible, and the prognosis of PLN-PAN+ is likely to be poor. The implications of a PLN-PAN+ lymphatic spread pattern should thus be taken into consideration when determining patient management strategies.