Why don't people commit suicide when they find out cancer or do they in a way because they delay seeking help?

Hope: Most cancers are treatable and many are curable. Going to suicide is not a positive way of approaching anything.

Suicide: Some dynamics are: fear of the unknown, demoralization, possible history of depression, fear of suffering from treatment, self image issues.

Meaning and Coping: People have many different ways of understnding life-threatening events, and there are alsom may ways of finding meaning and ways of coping with these difficulties. Also, people attach different meanings to the option of suicide. All of these factors lead to many people seeking to with with cancer instead of ending their lives. You are correct that delaying treatment can amount to passive suicide.

It's treatable: When I was a kid, we cured two out of six serious cancers; in my med school days three, now it's four out of six. Even when it's incurable, we usually have something pretty good to give cancer patients more good time. If you're concerned you may have cancer, please get seen, and even at the end we can manage the illness for your comfort.