Wondering if my use of dry shampoo a couple times a week is increasing my cancer risk?

Not to worry: Dry shampoo seems pretty innocuous, see: https://www.wired.com/2015/05/whats-inside-dry-shampoo/ Try not to inhale the actual spray too much; use in a ventilated space, such as with the bathroom fan on or near a window. Most carcinogens which may be in over the counter preparations are picked up and banned by the FDA, unless in the future the FDA gets gutted due to politics.