Vaginal and pelvic recurrences and salvage treatments in a cohort of Danish endometrial cancer patients not given adjuvant radiotherapy

OBJECTIVE: In Denmark, adjuvant radiotherapy has gradually been omitted after surgery in endometrial cancer. This study analyses the impact of this strategy on patterns of recurrence and outcome after salvage radiotherapy. Moreover, the potential effect of adjuvant radiotherapy is estimated in the non-low-risk cohort.

METHODS: The cohort included 3723 consecutive Danish patients with endometrial cancer who had radical surgery without adjuvant treatment (2005-2012). The patients were divided into low-risk (stage 1A, endometrioid, grades 1, 2 and no lymph-vascular space invasion) and non-low-risk. Crude/actuarial recurrence rates evaluated the number of patients who might have benefited from additional adjuvant radiotherapy.

RESULTS: Within 9 years' observation time using crude recurrence rates, 13.4% recurred.The rate of isolated vaginal recurrences was 2.9% in low-risk compared with 6.7% in non-low-risk patients. Isolated pelvic recurrences were 0.8% in low-risk compared with 2.1% in non-low-risk patients. In all, 15.8% of non-low-risk patients died from endometrial cancer, mainly due to primary or secondary non-local recurrences (a later non-local recurrence after a primary isolated local recurrence). Only 0.6% and 1.1% of all non-low-risk patients died from an isolated vaginal or pelvic recurrence, respectively. In all, 86% of all patients with an isolated vaginal recurrence were treated with curative intent. Of these, 72% were given radiotherapy with a local control rate of 91% (crude rate). However, even though only 5.8% died of an unsuccessfully treated isolated vaginal recurrence after curative intended radiotherapy, 23.1% died from a secondary non-local recurrence, while 22.3% died from other causes.

CONCLUSION: The Danish strategy of omitting adjuvant radiotherapy is safe. Adjuvant external beam radiotherapy may have prevented isolated local recurrences in 8.7% of the Danish non-low-risk patients, but a majority of these patients were salvaged by curative radiotherapy with 91% and 70% crude local control rates for isolated vaginal and isolated pelvic recurrences, respectively.