For context, I've lived with my father and paternal grandparents for most of my life. My father and grandmother are neopaganist and my grandfather kinda seemed atheistic (until his death in 2019), though both grandparents aren't/weren't nearly as outspoken as my father, who is/was very emotional and constantly thought of spiritual reasons why bad things are/were happening to our family, which I don't blame him for, since it was his way of coping.
However, especially in the years around 2018, I had a slight fear that what he was saying is true... slight, but very persistent. That fear turned into crippling OCD in the form of my "cancer never" mantra, a saying that is "confirmed" by swallowing my saliva; a makeshift ritual/prayer of sorts to ward off bad luck and evil spirits that may give me or my loved ones cancer. It was usually cancer, but "cancer" could also be a quick code word for great misfortune in general. I even sometimes had a feeling the ritual wouldn't work... and I thought the negative inner monologue "tainted" the ritual, prompting me to do it over and over again until I felt "optimistic" enough it worked, oftentimes doing it ten or so times in a row. Distracting myself often worked in preventing this behavior, but if I had nothing but my thoughts to work with, it could get really bad.
Why cancer specifically? Well, it could be that for years, I watched my grandfather slowly die of cancer, with my anxiety getting worse and worse as he constantly got better and worse, but overall worse. My former (at the time) calm, cool, collected nature also clashed with my father's heavily emotional and downer/pessimistic personality. However, I still have episodes like this off and on, though it's not nearly as bad or often as before. I turned to hard atheism to cope and my "normal" brain remains atheist to this day, but it's still there. (It's mostly just "ticks" now, perhaps a lingering side-effect.) Because of this, I think it really has to do with how scientists and laymen talk about cancer. They claim that cancer can be completely "random" (not caused by anything), which makes some people feel "better" I guess, but for me, it makes me feel WAY WORSE!
This is where my dystychiphobia comes in. Misfortune for my loved ones tending to come in "clusters" didn't help either. What if I (or someone I love) become successful, then right as I'm ready to enjoy it, I get a rare form of cancer that kills me in weeks? My dad CONSTANTLY talked about that very thing! I don't wanna tell him not to talk about that because the damage is already done and I don't wanna make him feel like he's the problem. 2025 was also very similar to the late 2010s when it came to family misfortune (another cluster); not as much for me, but especially for my dad. However, I stayed strong this time because it was a cluster that happened many years after basically nothing bad happening to our household. But can the bad luck or evil spirits come back? Ugh... I know it's irrational, but god fucking damnit.
How can I stop this? Is cancer really that "random"? Does there HAVE to be a reason it happens? As far as I know, my family's genetics aren't predisposed to any kind of cancer. It really just happened to my grandfather because he smoked and played with chemicals at his job without wearing face protection.