I am new to this forum, but sadly, not at all new to health anxiety. My focus seems to be cancer also; aways has been. Started in my mid teens and has lasted 25 years since then. The numerous- valid- legitimate health issues I faced compounded an occasional bout of HA into full blown panic on almost a weekly basis. It became so overwhelming after I had a (benign) tumor removed …I felt that I had 'lucked out', and the next issue would take me from my husband and kids. I wanted to escape my brain so I sought professional help.
I had started having significant improvement with intense therapy and occasional anxiety meds. After about a year, I finally was feeling it was controlled and my health thoughts were "normal", when out of the blue, my father was diagnosed with pancreatic cancer. After caring for him through hospice, He passed 8 weeks later. Several months after that my husband almost died and had emergency surgery that required over 6 months of rehab. Since those episodes, my HA has become disabling. I was diagnosed with PTSD, yet somehow the legitimate mental Dx from psychiatrist made me feel no better. I still feel like every bump, lump, ache or pain will somehow be my deadly diagnosis. Still doing the therapy, tried different meds, still down the "it's got to be a deadly cancer" rabbit hole. I am not giving up on trying to gain control over this fear. Hoping I will prevail. Wishing the same for all who suffer with this panic and fear.
I found your question about why certain diseases become the focal point for some, but not others. I have many theories….just wish there were easier answers to calm our fears.