Does postoperative prophylactic irradiation of para-aortic lymph nodes reduce the risk of recurrence in uterine cervical cancer with positive pelvic lymph nodes?

Background: In cervical cancer, para-aortic lymph nodes are common sites of metastasis. The purpose of the study was to evaluate the clinical benefits of prophylactic irradiation as postoperative therapy.
Methods: A retrospective cohort study was conducted during 2001-2015 at a single institution. Patients with a high risk of para-aortic lymph nodes recurrence were eligible for this study, and we identified patients who had pelvic lymph node metastasis and underwent radical surgery and concurrent chemo-radiotherapy. As a result, 33 and 46 patients were included in the treatment (prophylactic irradiation) and non-treatment groups, respectively. Baseline differences between the two groups were adjusted with the inverse probability of treatment weighting using propensity scores composed of the independent variables including age, stage, tumor size, pathological findings, lymph node status, and pathological subtypes.
Results: In the 68-month median follow-up period (range 6-178 months), 25 patients experienced recurrence, and 17 patients were dead. After adjustment with the inverse probability of treatment weighting, the recurrence rates tended to decrease in the treatment group, but there was no significant difference between the two groups [treatment vs. non-treatment, 29.4% and 44.3%, respectively; hazard ratio, 0.593 (95% CI 0.320-1.099); P = 0.097]. However, adjusted para-aortic lymph nodes recurrence rates were not significantly different [treatment vs. non-treatment, 7.8% and 11.4%, respectively; odds ratio, 0.660 (95% CI 0.187-2.322); P = 0.558]. Moreover, Kaplan-Meier curves showing post-recurrence survival revealed no significant difference between the two groups (P = 0.141).
Conclusions: Prophylactic para-aortic lymph nodes irradiation did not reduce the risk of recurrence.