How to update the page breadcrumb when using theme page I have an entity form(theme page to display it) .
I have used hook_node_view() to handle breadcrumbs for nodes.
But I don't find any place to handle this $breadcrumb when I have a form and a theme page for it.

This is how I got the $breadcrumb for my news. 

/**
 * Implements hook_node_view().
 */
function news_node_view($node, $view_mode, $langcode) {
  if ($node-&gt;type == 'news' &amp;&amp; $view_mode == 'full') {
    //BREADCRUMB ////
    $breadcrumb = array();
    $breadcrumb[] = l('Home', '&lt;front&gt;');
    $breadcrumb[] = l('News', 'news');
    drupal_set_title('News');
    drupal_set_breadcrumb($breadcrumb);
  }
}


I have hook functions like:

hook_init()
hook_menu()
hook_form()
hook_form_validate()
hook_form_submit()
hook_theme()
hook_preprocess_form()


But I don't find a place to work on $breadcrumb, or somehow manage it.
If you are looking for GUI to handle breadcrumbs, take a look at Custom breadcrumbs module.
Otherwise, you can manage your breadcrumbs programatically in lot of hooks. The code you've printed is correct, so you can create for example a function with a switch case like this one :

function manager_breadcrumbs($form_id) {
  $breadcrumb = array();
  $breadcrumb[] = l('Home', '&lt;front&gt;');
  switch ($form_id) {
    case 'my_first_form' :
      $breadcrumb[] = l('Category', 'taxonomy/term/1');
      break;
  }
  drupal_set_breadcrumb($breadcrumb);
}


And then, call this function in a hook_form_alter() like this.

function MY_CUSTOM_MODULE_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  manager_breadcrumbs($form_id);
}