Long term Herceptin for Stage IIIC

I was dxed may 05 ; age 49 (premenopausal)with stage  III BC, 12 pos nodes out of 14  (extracapsular positive sentinel & axillary nodes), LVI, er/pr negative, her 3+ on fish, Did lumpectomy, axillary dissection, then MRM ( 1 mm dirty margin- chest wall ), 4 cycles DD AC, then Taxotere w/ Herceptin X 4 cycles; q 3 wks.
I have continued Herceptin q 3 weeks( no breaks) .added Zometa Q 6mos; 2yrs ago.
I continue to have yrly clean PETS.( I don't know of anyone non metistatic  that  has been on Herceptin  for over 2 yrs)
My ? is when I do go off  Herceptin @ 5yrs , will my recurrence risk drop because of active tx time? or should I just stay on unitl one of the oral erb2 inhibitors become avail ?
Thank you so much!

[Cleveland Clinic]

Dear lkmaa:  Most of the clinical trials evaluating trastuzumab (Herceptin) in operable breast cancer (stages I through III) used one year of treatment and therefore that is what is most commonly given in this setting. There is an ongoing clinical trial that will compare one year to two years but until the results of that study are available we will not have information on the long-term safety or whether there is added benefit to continuing treatment beyond one year in nonmetastatic disease. Since each person’s situation is different, however, you should discuss this further with your oncologist.