I don’t see my brother a lot

Mum told me he has a tumour in his ear but she said it’s benign and he just needed surgery.
But I spoke to him myself yesterday and turns out he’s lied to her so she doesn’t worry.
I said I wouldn’t say anything.
He’s right, she will make herself sick worrying.
It might well be benign but they don’t actually know yet. They’re also worried it might spread to his brain. What he said sounded really scary, and he’s having trouble with his other ear now as well which makes me think it is cancer and it has spread.
So now I’m worrying myself sick.
It’s weird because we don’t really agree on a lot of things. He’s conservative and a lot of the things he votes for make my life and the lives of my family worse. He doesn’t see that though.
He’s a chill kind of guy so when you’re with him it’s easy to get on. He doesn’t create issues with anyone, he’s always just accepted people as they are and minded his own business. I have seen him once or twice in the last few years and we talk on WhatsApp sometimes.
But he’s my little bro so I still feel close I guess. Idk
Can’t stop thinking about it.