i presume you have had a Radical prostatectomy
for Prostate Cancer
. it is glad to know it has been 7 years and you are apparently well.
when a treatment is offered for cancer, we talk of cure rates. in organ confined prostate cancer, the 5 year cure rates are 90 to 92%. that means, the remaining 8 - 10 people will have a recurrence of prostate cancer at some point in time.
for prostate cancer, PSA is a marker for both diagnosis and follow up after treatment.
PSA becomes a very sensitive marker, in particular, after surgery.
it is imperative that you follow up with serial PSA tests after surgery as your doctor could identify disease recurrence, in case there is, very early and offer you curative treatment again.
Prostate cancer can recur for many years after treatment but the chance of recurrence decrease as time passes. with this regard, you seem to be pretty much cured of your disease.
however, you need to continue PSA monitoring, perhaps lifelong just to ensure you do not get the disease back.
Be reassured but do not stop following advice of your doctor!