The EAU and the AUA does not recommend any value to screen adenomectomized patients. The incidence of prostate cancer in this patients is a 10% aprox.

usually you did already PSA estimation before doing adenomectomy...and to follow up the patient later on- about 6-12 months - for development of cancer it will follow the same parameters for normal persons of the same age, ...unless histopathology showed pT1a, or b,  when you chose between active surveillance, radical surgery or EBRT or ADT+brachytherapy...or watchful waiting as the patient already had been diagnosed, so progression will be dependent on PSA after 3 months according to 2014 NICE protocol for active surveillance. In conclusion it is not the level of PSA but PSA Kinetics which are important in detecting such cancer.

https://www.nice.org.uk/guidance/cg175/resources/cg175-prostate-cancer-protocol-for-active-surveillance2

Should the pathology if the removed specimen is BPH, PSA would decline after few weeks to a much lower level but there are no nomograms for this. It is a point worthy of studying