Ovarian cancer

A sample of 100 healthy middle-aged women was followed for 9 years. All subjects entered the study on January 1, 2009, and all women were followed until December 31, 2017. None were lost to follow-up, and no one died during this period. During this period, five subjects were diagnosed with ovarian cancer, but all survived until the end of the study. None were cured. The time at which these subjects developed cancer Question 1 What was the prevalence (%) of ovarian cancer on January 31, 2009? Question 2 What was the prevalence (%) of ovarian cancer on December 31, 2017? Question 3 What was the cumulative incidence (%) of ovarian cancer over the 9-year period?