Are all private health PPO insurance plans 1 year terms?

I am self employed and trying to get insured for myself through Blue Shield of CA. I'm going through a broker, they seem to be the biggest one and I have the impression they are maybe directly under Blue Shield itself. Anyway, all the plans state that they are for 12 months. Does this mean you can't cancel before 12 months or that after 12 months you have to re-apply from scratch? If you're in CA can you recommend somewhere to buy the plan from? I am going through Blueshieldca.com. It's just for myself but if I don't like the plan or want to go back to my HMO I don't want to be tied up for a whole year OR if I end up using a doctor or being hospitalized I don't want to re-apply in a year and not get approved. I've only been with Kaiser HMO and I had the freedom to cancel at any time.