Calling ShowDialog in BackgroundWorker

My background worker is doing a sync task, adding new files, removing old ones etc.

In my background worker code I want to show a custom form to user telling him what will be deleted and what will be added if he continues . with YES/NO buttons to get his feedback.

I wondering if it is ok to do soemthing liek this in background worker's doWork method ?
if it is not safe how should I do it

Please advise..

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
 {
    MyForm f = new MyForm();
    f.FilesToAddDelete(..);
    DialogResult result = f.ShowDialog();
    if(No...)
    return;
    else
    //keep working...
 }
 

---