Internal medicine

Cohort study

Cancer registry

Population

Relative risk

Cancer

Obstetrics

Oncology

Prospective cohort study

Endometrial cancer

Levonorgestrel

Family planning

Gynecology

Ovarian cancer

Breast cancer

Cohort

Research methodology

Confidence interval

Medicine

Poisson regression

Environmental health

Gynecologic Oncology

In 2012, ovarian cancer caused an estimated 152,000 deaths worldwide [2]. The cumulative risk of ovarian cancer until age 75 is 1.3% in Norway and is similar in the United States [3,4]. The symptoms of ovarian cancer are vague, and there is no screening test. This has led to problems of late diagnosis and a 5-year survival of <50% [5]. Thus, ovarian cancer ranks eighth in cancer incidence, but fifth in cancer mortality among women [4]. Primary prevention therefore remains the best available measure against ovarian cancer [5].

Levonorgestrel-releasing intrauterine system use is associated with a decreased risk of ovarian and endometrial cancer, without increased risk of breast cancer. Results from the NOWAC Study