I'm sorry that's been your experience, @Rose18. I 've been incredibly lucky, & well supported in my workplaces since my diagnosis. Nearly 3 years on, I've just started a new job this week. Time will tell if my luck continues. I haven't outright said that I've had cancer, but it's fairly obvious that something has gone on, as I have lymphoedema and wear a compression sleeve & glove.
Is there any way that you could broach the subject with a manager, or someone in HR? Does your workplace have a policy on bullying? And do you have access to an Employee Assistance Program, (EAP) to access a counsellor to help with some strategies?
Take care