Hello I have gone through your question and understand your concern. Firstly, let me explain you 8n brief what are tumor cells or a tumor. It is just normal cell or cells who lost their ability to control the dividing capacity and they keep on replicating thereby taking nutrition of normal cells just like weeds in a garden. Secondly, anything can initiate the sudden change ir mutation in cells from physical injuries like trauma to chemicals and radiation. Any clear medical records like M.R.I or CT scan taken anytime prior to injury can also help in understanding the cause of tumor and its relation to truma. Hope your concern is answered. Thank you.