Question
A sample of 100 middle aged and elderly women was followed prospectively for 10 years in order to study rates of ovarian cancer. All subjects entered the study on January 1, 1990, and all were free of cancer at the beginning. All women were followed until December 31, 1999. None were lost to follow-up. During this period, five subjects were diagnosed with ovarian cancer, but they all survived to the end of the study.
Case #1 was diagnosed with ovarian cancer in January 1991.
Case #2 was diagnosed in January 1992.
Case #3 was diagnosed in January 1993.
Case #4 was diagnosed in January 1986.
Case #5 was diagnosed in January 1996.
The time at which these 5 subjects developed cancer is shown in this table:
Using this information and the information in the table below, what was the breast cancer incidence rate?
Subject
|
1990
|
1991
|
1992
|
1993
|
1994
|
1995
|
1996
|
1997
|
1998
|
1999
|
Case #1
|
cancer
| |||||||||
Case #2
|
cancer
| |||||||||
Case #3
|
cancer
| |||||||||
Case #4
|
cancer
| |||||||||
Case #5
|
cancer
|
Source:
