Bf had thyroid(papillary) cancer-common and very treatable- and had his thyroid gland removed and now his brother needs a kidney due to kidney failure from lupus. Bf wants to now donate his kidney. Would it be a risk marrying him? having healthy children? his life span??

Please help, I plan on getting married this upcoming December in the Dominican Republic. I was told that I need to get my birth certificate translated into Spanish and notarized, where can I go to get that done? I live in Denver, Colorado. Thanks !!!!!!!