since prostate - specific antigen ( psa ) was demonstrated in prostatic tissue in 1970 , measurement of the serum psa level has become widely used for the early diagnosis and management of prostate cancer .
however , it is well known that an increased serum psa level does not always indicate the existence of prostate cancer .
the serum psa level can also be increased in patients with benign prostatic hyperplasia ( bph ) , in patients with prostatitis , and after interventions such as prostate biopsy and transurethral resection of the prostate ( turp ) . especially in patients with mildly increased serum psa
( 4 - 10 ng / ml ) , the single most common cause of serum psa elevation is known to be bph , rather than prostate cancer .
other benign prostatic diseases that can cause elevation of the serum psa level include acute urinary retention , acute prostatitis , and prostatic ischemia .
moreover , it has been reported that the serum psa level has a tendency to increase temporarily for 20 days after turp and will decrease afterwards .
therefore , it is difficult to distinguish prostate cancer from benign prostatic conditions in patients who have undergone interventions on the prostate .
one report on this issue suggested that 3% of patients who have undergone surgeries for bph will actually develop prostate cancer during the follow - up period ; thus , establishment of clinical guidelines for follow - up strategies for such patients is necessary .
it is now well understood from several reports on changes in the serum psa level after turp that the serum psa level decreases after turp . by contrast , reports on changes in the serum psa level after potassium - titanyl - phosphate ( ktp ) laser vaporization of the prostate based on the analysis of large populations are rare .
treatment of patients with bph by 80 w high - power ktp laser vaporization was first introduced in clinical practice in 2000 and is now accepted as an effective minimally invasive treatment modality .
this method eliminates prostatic tissues that cause obstruction through vaporization , which occurs when hemoglobin selectively absorbs the ktp laser that generates heat energy .
ktp laser vaporization has gained considerable attention among many urologists recently because this treatment modality is less invasive while offering treatment results similar to those of conventional turp .
hwang et al reported that patients who underwent ktp laser vaporization demonstrated significant improvements in international prostate symptom score ( ipss ) , maximal flow rate ( qmax ) , quality of life ( qol ) , and residual urine 3 months after the operation . because the use of ktp laser vaporization is expected to increase , a need exists for establishing patterns in changes in the serum psa level after the operation .
the elucidation of such patterns might offer useful clinical information on appropriate management and follow - up strategies .
a total of 662 patients underwent ktp laser vaporization of the prostate for bph between october 2004 and august 2008 . among these patients , those with prostate cancer , prostatitis , a history of urinary retention , or use of antiandrogen medication , all of which can influence serum psa levels ,
also excluded were patients for whom insufficient data were available or who were lost to follow - up .
therefore , 278 patients were included in the prospective analysis of serial serum psa levels .
careful history taking , digital rectal examination ( dre ) , ipss , urinalysis / urine culture , transrectal ultrasound ( trus ) , qmax , postvoiding residual urine ( pvr ) , and serum psa levels were checked in every enrolled patient and evaluated to determine whether to perform ktp laser vaporization .
patients with abnormal dre findings or a serum psa value of 4.0 ng / ml or higher underwent trus - guided 12-core prostate biopsy to detect and exclude prostate cancer .
prostate volume was estimated by trus , first by measuring length ( l ) , width ( w ) , and height ( h ) and then by calculating volume by use of a prolate ellipsoid formula ( lwh/6 ) . either epidural or subarachnoid anesthesia was used for the operations , and the vaporization was carried out by use of an 80 w ktp laser system ( greenlight pvtm ; laserscope , san jose , ca ) that uses a 6 fr side - deflecting optical fiber emitting laser at a wavelength of 532 nm , which is delivered through a 23 fr , 30 continuous flow cystoscope connected to videoendoscopy .
the distance from the probe to the prostatic tissue was kept closer than 2 mm , and normal saline was used as the irrigation fluid .
the vaporization was performed until the tissues that caused the obstruction were completely removed , resulting in the formation of an appropriately sized cavity .
a foley catheter ( 16 or 18 fr ) was inserted right after the procedure and was removed one day later .
serum psa levels were measured in every patient before the operation and 1 , 3 , 6 , and 12 months after the operation to analyze patterns of change .
in addition , serum psa levels at 24 months after the operation were also checked in 183 patients . the mixed linear model in spss ( version 12.0 , spss inc ) was used for statistical analysis of the changes in the serum psa level , and statistical significance was defined as a p - value of less than 0.05 .
the mean age of the patients was 69.0 years ( range , 50 - 91 years ) .
the mean serum psa value was 2.722.93 ng / ml , and mean prostate volume estimated by trus was 35.715.5 cc ( table 1 ) . the serum psa level temporarily increased and reached 3.183.23 ng / ml at 1 month after the operation ( p=0.032 ) .
however , levels began to decrease continuously afterward and decreased to 1.922.26 ng / ml in 3 months ( p<0.001 ) and 1.791.82 ng / ml in 6 months ( p<0.001 ) .
within 12 months , the serum psa level was 1.702.25 ng / ml ( p<0.001 ) , thus demonstrating a decreasing pattern of stabilization ( table 2 , fig .
the decreasing pattern showed its greatest value between 1 month and 6 months ( fig .
1 ) . the serum psa level at 24 months after the operation was not checked in all patients , but it also was shown to decrease and stabilize ( table 2 ) . as a result ,
the serum psa level had decreased by 37.5% by 12 months after the operation compared with the preoperative level .
bph is a common disease in older men ; 40% to 70% of men over the age of 60 years are suspected of having bph , and it is still on the rise along with increasing life expectancy and westernized diets .
turp is accepted as the standard surgical method for treating the lower urinary tract symptoms of bph , although several other treatment options have been developed to date .
however , complications of turp such as bleeding , tur syndrome , urethral stricture , retrograde ejaculation , and urinary incontinence are still among the side effects of this procedure and have not decreased significantly despite developments in techniques and instruments .
ktp laser vaporization of the prostate was introduced in the 1990s but was not widely accepted as an effective treatment option because it was performed with a low - power ( 20 w , 34 w ) ktp laser in the early years and required a relatively longer surgical time than conventional turp .
more recently , however , the 80 w high - power ktp laser was developed to improve vaporization speed , and as a result , ktp laser vaporization has become an effective treatment modality .
malek et al proved its efficacy by reporting that patients with prostates over 45 cc who underwent 80 w ktp laser vaporization showed significant improvements in ipss , qol , qmax , and pvr within 5 years of follow - up .
therefore , ktp vaporization is now widely practiced in many institutes because of its efficacy and reduced invasiveness , even though some controversy remains concerning its complication rates compared with conventional turp [ 13 - 15 ] .
ktp laser vaporization can not eradicate prostate cancer that originates in the peripheral zone , however , because it only eliminates tissues at the transitional zone of the prostate .
marks et al reported that among 82 patients who underwent turp to treat lower urinary tract symptoms , prostate cancer had developed in 6 patients within 5 years of follow - up . with ktp laser vaporization in particular , possible pathologic diagnosis of prostate cancer
could be missed because it is impossible to obtain a prostate specimen from the operation , which is possible in conventional turp .
therefore , it would be useful to establish clinical guidelines by serum psa follow - up after the operation to detect coexisting prostate malignancy with bph . to date , however , only limited reports on serum psa changes after ktp laser vaporization of the prostate were available .
it is widely known that serum psa levels generally increase after interventions on the prostate for a certain period of time and decrease afterward .
temporary elevation of the serum psa level occurs as a result of psa leakage to the systemic circulation due to damage to the blood - prostate barrier during manipulations .
in addition , prostatic inflammation after the manipulation can also facilitate increases in the serum psa level .
there are several different reports on the length of time it takes for the serum psa level to decrease after a procedure .
volkan et al reported that the serum psa level increased immediately after ktp laser vaporization , but eventually decreased and returned to its preoperative level within 15 days after the operation . in our series ,
the serum psa level increased for up to 1 month and then decreased significantly over the next 3 months .
it is not possible to clearly explain this variability in the length of time for which the serum psa level is increased .
further investigation of the probable responsible factors , such as differences in prostate volume , the preoperative serum psa level , operating time , and devices , are necessary to clarify this matter .
aus et al analyzed the serum psa level of 190 patients who underwent turp and reported that the serum psa level was reduced by 70% compared with its preoperative level .
they also reported that the serum psa level became lower than 4 ng / ml in 90% of those patients .
wolff et al also reported that the serum psa level became stabilized at 2 ng / ml or higher in patients who were diagnosed with prostate cancer after turp .
therefore , similar to patients who undergo turp , the possible existence of prostate cancer should also be considered in patients who demonstrate a serum psa level that remains high or increases constantly after ktp laser vaporization . in our study , the serum psa level decreased significantly within 3 months after the operation and showed only a slight decrease from 6 to 12 months , which might mean that the levels stabilize after 6 months . in the present study , we were able to accurately analyze the changes in the serum psa level after ktp laser vaporization by frequently checking the postoperative serum psa level in a relatively large population for more than 1 year .
the serum psa level may be temporarily increased after ktp laser vaporization for a certain period of time , but values will show a decreasing pattern within 3 months and will eventually become stabilized between 6 and 12 months .
therefore , it may be appropriate to wait for 3 months if the serum psa level rises after the procedure . however , if the serum psa level remains high even after 6 months , close follow - up or further investigation should be considered .
 purposethe prostate - specific antigen ( psa ) level decreases after transurethral resection of the prostate ( turp ) . 
 however , changes in the psa level after potassium - titanyl - phosphate ( ktp ) laser vaporization of the prostate are not well known . 
 the aim of this study was to investigate the effect of ktp laser vaporization of the prostate on psa levels in patients with benign prostatic hyperplasia ( bph).materials and methodsserum psa levels were checked before and 1 , 3 , 6 , and 12 months after the procedure in patients who underwent ktp laser vaporization between october 2004 and august 2008 . 
 patients with prostate cancer , a history of urinary retention , or prostatitis during the follow - up period were excluded . 
 the results for 278 patients were studied.resultsthe mean age of the patients was 69.06.7 years ( range , 50 - 91 years ) and the mean preoperative psa level was 2.722.93 ng / ml . the psa level tended to be increased at 1 month after the operation ( 3.183.23 ng / ml , p=0.032 ) but decreased within 3 months and became stabilized after 6 months at 1.791.82 ng / ml ( p<0.001).conclusionspsa levels may increase after ktp laser vaporization for a certain period of time , but eventually decrease and become stabilized after 6 months . therefore , it may be appropriate to wait up to 3 months if the psa level rises after the procedure , and further investigation should be considered if the psa level still remains high after 6 months . 