Hi Monya
I can't see a specific answer to your question in the CC FAQ, but it seems sensible that you could cancel your current plan, and take out a full subscription. If you are tied into a year's single app subscription, then my best guess is that you would need to make the full subscription a year's commitment as well.
But since they introduced the bargain priced Photography deal for Photoshop CC and Lightroom 5 of $10/month, $50/month for a full subscription feels just a tiny bit steep IMO. It would have been nice if Adobe extended the same good will to pro customers with say, a $40/month deal.