Long‐term incidence of endometrial cancer after endometrial resection and ablation: A population based Swedish gynecologic cancer group (SweGCG) study

INTRODUCTION: Minimally invasive methods to reduce menorrhagia were introduced in the 1980s and 1990s. Transcervical endometrial resection (TCRE) and endometrial ablation (EA) are two of the most frequently used methods. As none of them can guarantee a complete removal of the endometrium, there are concerns that the remaining endometrium may develop to endometrial cancer (EC) later in life. The primary aim was to analyze the long‐term incidence of EC after TCRE and EA in a nationwide population. The secondary aim was to assess the two treatment modalities separately. MATERIAL AND METHODS: The Swedish National Patient Registry and National Quality Registry for Gynecological Surgery were used for identification of women who had TCRE or EA performed between 1997–2017. The cohort was followed from the first TCRE or EA until hysterectomy, diagnosis of EC, or death. Follow‐up data were retrieved from the National Cancer Registry and the National Death Registry. Expected incidence for EC in Swedish women was calculated using Swedish data retrieved from the NORDCAN project after having taken into account differences of age and follow‐up time. Cumulative incidence of EC after TCRE and EA, was calculated. A standardized incidence ratio was calculated based on the expected and observed incidence, stratified by age and year of diagnosis. RESULTS: In total, 17 296 women (mean age 45.1 years) underwent TCRE (n = 8626) or EA (n = 8670). Excluded were 3121 who had a hysterectomy for benign causes during follow up. During a median follow‐up time of 7.1 years (interquartile range 3.1–13.3 years) the numbers of EC were 25 (0.3%) after TCRE and 2 (0.02%) after EA, respectively. The observed incidence was significantly lower than expected (population‐based estimate) after EA but not after TCRE, giving a standardized incidence ratio of 0.13 (95% confidence interval [CI] 0.03–0.53) after EA and 1.27 (95% CI 0.86–1.88) after TCRE. Median times to EC were 3.0 and 8.3 years after TCRE and EA, respectively. CONCLUSIONS: There was a significant reduction of EC after EA, suggesting a protective effect, whereas endometrial resection showed an incidence within the expected rate.