Correct way to cancel an async Task?

Lets say I have a search bar and a listView in a Content Page...
When I search for a text I run an async task that gets some info from a Rest Server.
But if I pop the page before the Task is completed I get an exception when it try to run something on MainThread.
A piece of the code:

        SearchBar searchBar = new SearchBar
                {
                    Placeholder = "Search",
                };

                searchBar.SearchButtonPressed += OnSearchBarButtonPressed;

                ListView listView = new ListView
                {
                    VerticalOptions = LayoutOptions.FillAndExpand,
                    RowHeight = 10,

                };

        async void OnSearchBarButtonPressed(object sender, EventArgs args)
            {

                SearchBar searchBar = (SearchBar)sender;
                string searchText = searchBar.Text;
                await Task.Run (async () => {
                    await GetInfo (searchText);

                });
            }

        private async Task GetInfo (string searchText)
        {

            searchList = await GetList (searchText);


            Device.BeginInvokeOnMainThread (async() => {

                        listView.ItemsSource = searchList;

            });
        }

        public static async Task<List<String>> GetList (string searchText)
        {

            //Get List throught Rest Server

            return searchList;
        }

To Cancel it I was trying to use a Cancelation Token...
I saw this topic and this tutorial and send a CancelationToken to my tasks as parameters and onDisapearing I called

          if (cts != null)
            {
                cts.Cancel();
            }

To Cancel the tasks but not sure if just passing the CancelationToken as an argument is enought and if Im doing right!

Any help?