Applying for PhD overseas After a Break
Actually, I think it is a mistake to try to submit without letters. People will wonder about your motives and worry that you don't think you can get good recommenders. 

Your break isn't that long, actually. After 20 years it would be different. Your old professors probably still remember you if you did good work. Of course, you will need to reintroduce yourself, bring them up to date on what you have done recently, and remind them of what you did in the past. 

But, assuming that you had a good enough relationship back then to have asked, that hasn't changed. It is certainly appropriate to do so. Many professors, in fact, are happy to hear about old students and to support their further advancement.