This is extremely sad news. Elisabeth Sladen and Jon Pertwee were my first companion and Doctor, how I was introduced to Dr. Who. I also loved her in the Sarah Jane Adventures, even though I'm a little old for it now (wait... what am I saying?!). Never knew that she was battling cancer, that's really awful. Such an amazing person, both off screen and on screen, she will definitely be missed.
There are still a couple of unaired episodes of
Sarah Jane Adventures left.
Not sure if they'll continue the series without her.