Identify the flaw in the following study At one hospital 674

Identify the flaw in the following study:

At one hospital 674 women were diagnosed with breast cancer. Five years later, 88% of the Caucasian women and 83% of the African American women were still alive. A researcher concludes that being Caucasian causes women with breast cancer to have an increased chance of surviving five years. Why is this conclusion not justified?

Solution

Since out of 674 womens who had breast cancer before 5 years are not being classified as how many are Caucasian women and how many are African American, so if 88% of the Caucasian women and 83% of the African American women were still alive, it can not be said that Caucasian women have increased chance of surviving five years.

And death is not caused by breast cancer only, So it can not be concluded that being Caucasian causes women with breast cancer to have an increased chance of surviving five years.