How can I determine that a invisible object can cast shadows in the camera frustum?

Hello!

To keep things, short, I have a system that manually draws data instanced. Using 'GeometryUtility' i can see if world bounds intersect the camera frustum. However there are objects outside the frustum that can cast shadows INSIDE the camera's view data.

I need some sort of way to see how can I see if an object (in the example it's B) casts shadow into the camera, having a directional/spot light in the scene.

Thanks!