The risk of cancer at the place of drug delivery is not associated with the intravenous drug delivery. This is not possible. Cancer can be defined as the undefined growth of the cells which becomes cancerous in nature.
They keep on proliferating which is only possible when there is no check points for the cells.
The normal cells of the body can also become cancerous and starts proliferating skipping the cell cycle. This is not possible due to intravenous drug delivery.
I honestly feel everyone is different but me personally I deal with stress by breathing exercises. It feels good and it makes me get rid of my stress. I also take baths and do my breathing exercises in there as well.