AFAIK that's only for meat cured with SN. Even then, it's carcinogenic, not "cancerous" - it increases the likelihood for you to get cancer at some point in your life, but generally only has significant effects if you make eating cured meat a habit. I haven't heard about SN itself causing cancer. Maybe the SN might "cure" your stomach meat a bit after ingestion, and give you a moderate dose of nitrosamines...?
At worst, even if that were to happen, it would be a very very small increase in your chance for cancer. Cancer's not your concern with this method.
SN is relatively safe from side-effects, probably one of the lowest odds of serious side effects of almost any method. You would have to be extremely unlucky and be 'saved' at the very brink of death to suffer any kind of permanent brain damage, etc.