ComboBox SelectedIndexChanged event: how to get the previously selected index?

I have a user control which has a ComboBox and a SelectedIndexChanged event handler. In the event handler, I need to be able to tell what was the previously selected index... can anyone point me in the right direction?

private void cboTargetMode_SelectedIndexChanged(object sender, EventArgs e)
{
    // need to get the previously selected index and do some handling here...
    // ... some handler code here ...


    switch (cboTargetMode.SelectedIndex)
    {
        case 1:  // ..... some code here...
            break;
        case 2:  // ..... some code here...
            break;
        case 3:  // ..... some code here...
            break;
        default: // ..... some code here...
            break;
    }
}