But I’ve been thinking, and it occurs to me that Elisabeth Sladen almost drowned in that cave river at Wookey Hole, back in the Seventies when they were filming the Cybermen episode. She was only saved by dint of a crewmember almost getting himself drowned going after her.
That would have been really dying young. Everything since then has been bonus time.
And of course, plenty of people do still die of cancer. It’s unusual to have two from the same show die close together, but different kinds of cancer are radically different from each other.