do a psoriasis patient never get cancer?

I haven't heard of that theory yet but as far as I know, psoriasis is caused by over active immune system. Once the immune system becomes over active, it results to imbalance. Our immune system is like the national defense of a country, it is the defense of our body. When it becomes over active, it attacks our own body. This results to psoriasis, arthritis, asthma, lupus, allergies, and most diseases with "itis". Cancer is caused by immune system's under reaction. In this case, the soldiers of the immune system or what is called the Natural Killer Cells (NK Cells)is not doing its job....to kill the viruses and bacteria in the body. Everyday we develop cancer cells, and since our immune system are performing its job, cancer cells gets killed and destroyed by the NK cells so there's no chance for them to grow. 1 NK cell kills 1 cancer cell, its a number game. Once the cancer cells grow in number more than the NK cell, that's the start of the disease. Worse is, these cancer cells do not stay in one place, they migrate to the different parts of the body carried by the blood circulation, this is what they call metastasis. Based on the above, these 2 diseases you mentioned is caused by 2 different causes...psoriasis is over active immune system and cancer is under reaction of the immune system. Cancer cells will have no chance to grow in a body with an over active immune system. Your psoriasis can be cured. I know some people who gets well from it.