I got annual multi-trip worldwide with Nationwide FlexPlus at a reasonable price - might be worth getting a quote from them - hope you enjoy your cruise!
I have found Insurancewith (all one word) very reasonable since I started travelling again after treatment finished.
Also Allclear .I finished active treatment in March and I took out an annual european policy with them at reasonable cost starting May this year.
The company I use for myself and my husband is Staysure, they havel always been very helpful re medical conditions.
Looking for any advice on companies that offer reasonable holiday insurance for my honeymoon (Europe) in 3 weeks. Treatment for BC ended in March,