The A League of Their Own star blogged her concerns to friends and fans on Monday (15Nov10) and has since opened up about her health worries on TV in America.
O'Donnell tells news show Extra she fears she may have the same disease that killed her mother.
She says, "My mother died at 39."
In a blog to fans, she insisted, "They (doctors) say it looks good."
O'Donnell, who had a lump removed when she turned 30, should have the results from her biopsies later this week (ends19Nov10).