Hi lnvs, hi all,
this has been an area of special attention for me. I have wondered continually about the connection, and have viewed many a paper and article to support this connection.
The connection goes something like this: Trauma=disruption/interference to nervous system=breakdown/exhaustion of immune system. Cancer begins as a virus, something that lives as a potential for all people. It is the immune system's ability to fight the virus that is key to "getting" cancer. If the immune system is in some way challenged in cannot do this.
But, there are other things that can compromise the immune system too, such as digested toxins - ie poisons (food), electrical charges (wi fi and the like), microwaves... etc, etc. These all, in someway, provide the same results to the nervous system as a traumatic experience - essentially they are all traumas, all disturbing the nervous system, and thus immunity.
Please keep in mind that this is a simple explanation of something more complex.