Place download request in one tab but complete in another

A web app opens new tab and places a POST request to the server to create a file for a download. Here is the code that sends the file back:

Response.AppendHeader("content-disposition", "attachment; filename=name");
Response.ContentType = "application/octet-stream";
Response.WriteFile(zipPath);
Response.Flush();
Response.End();

What can happen is that the user can close the new tab and no download would take a place. Is there any chance that the app would still get the file? I understand that placing request in the app is the way to go, but I am dealing with existing architecture.

Thanks for help.