I have heard some researchers say that self breast checking has led to a lot of panic over benign tumor growth.
There are a lot of reasons why you might have a lump in your breast, so if you find one you shouldn't panic about it, although you should get it checked.
I find it interesting that some research has said that all the self breast exam literature has not led to much more early detection, as much as it has led to a lot of false alarms.
I wonder if this is because by the time most lumps are at the point where you can find them, they are already causing symptoms anyway?
At any rate, the recommendation is that if you are at risk, you should go and get screening, rather than rely on your own breast exams.