navigation controller "Back Button" canceling all activities.

[Triston]

in my root view(UITableView), when user click on the cell, it pushes another table view displaying all the data pulling from a remote server. During the process is running, users are able to press the back button, if the users press the back button, then click on another table cell in the root view, all data from the previous activity and current activity will be displayed in the table.

May i implements the "Back Button" to cancel all the background activities?

thanks