Prostate cancer is currently the most common malignancy in Western countries, with 232,090 new cases of prostate cancer and 30,350 deaths from prostate cancer in the United States in 2005. In recent years, the incidence of prostate cancer in China is also increasing year by year. Prostate puncture biopsy is the “gold standard” for prostate cancer diagnosis, but some patients with early stage limited prostate cancer still cannot be diagnosed by prostate puncture biopsy in a timely manner and need to undergo secondary biopsy. The authors intend to conduct a comparative study of tumor screening in patients with suspected prostate cancer with TPSA < 20 μg/L by ultrasound-guided 24-stitch saturation puncture of the perineal prostate and the previous 14-stitch biopsy technique. 1. Data and methods 1.1 Clinical data 116 patients with suspected prostate cancer with TPSA < 20 μg/L between March 2006 and March 2010 were selected for ultrasound-guided 14-needle trans-perineal prostate aspiration biopsy (14-needle group), aged 54-83 years, mean 74.5 years. Between April 2010 and September 2011, 136 patients with suspected prostate cancer with TPSA <20 μg/L underwent ultrasound-guided 24-stitch trans-perineal prostate saturation aspiration biopsy (24-stitch group), aged 48-85 years, with a mean of 75.4 years. All patients met the indications for prostate puncture biopsy: (1) TPSA 10-20 μg/L or (2) TPSA 4-10 μg/L and FPSA/TPSA <0.25 or (3) prostate cancer could not be excluded by rectal examination or magnetic resonance. 1.2 Operation method: Spinal or intravenous basic anesthesia, lithotomy position, perineal disinfection, probing of the rectal ultrasound probe into the rectum, simultaneous placement of the perineal puncture locator (Branchtherapy grid), careful observation of the prostate echogenicity under ultrasound, and measurement of prostate volume. 1.2.1 14-stitch puncture method The largest cross-section of the prostate was taken and 12 stitches were punctured using an 18G prostate puncture biopsy gun (BARD), of which "2", "3" and "2 The four puncture sites of "2", "3" and "2" and "3" were from the prostate metastasis. Afterwards, 2 additional biopsies were performed in the apical region of the prostate, for a total of 14 stitches. 1.2.2 24-stitch saturation puncture method The prostate was divided into three coronal levels: basal, central and apical under rectal ultrasound, and the biopsy operation was performed using an 18G prostate puncture biopsy gun (BARD). Eight stitches were made at each prostate level, for a total of 24 stitches. The "2", "3", "4", and "5" puncture sites were from the prostatic migratory zone (Figure 2). All puncture tissues in both groups were ≥ 1 cm in length, and antimicrobial agents were used to prevent infection for 3 days after the operation. The age, PSA level before puncture, PSA density [PSA density = serum PSA (μg/L) / prostate volume (ml)], prostate volume, positive prostate cancer screening rate, positive prostate puncture specimen rate [positive specimen rate = number of positive specimens / total number of puncture specimens], and complications such as urinary retention and urinary tract infection after puncture were recorded in both groups. The rate of positive specimens [positive specimen rate = number of positive specimens/total number of specimens] and complications such as urinary retention and urinary tract infections after puncture. 1.4 Statistical analysis The statistical software was SPSS version 17.0, and the t-test was used for independent samples for age, TPSA, PSA density, etc. The χ2 test was used for count data such as positive prostate cancer screening rate, positive puncture specimen rate, hematuria and infectious complications between the two groups. 2. Results There were no statistical differences in mean age, pre-puncture PSA level, mean prostate volume, PSA density and other indicators between the two groups. The positive prostate cancer screening rate in the saturation puncture group was 48.53%, while the positive rate in the 14-needle group was 17.24%, which was statistically significantly different (p=0.0007), and the positive specimen rates were 8.09% and 2.83%, respectively (p=0.012); in which the detection rate of tumors in the prostate apical region was significantly higher in the saturation group (11.76%) than in the 14-needle group (1.72%). There was no statistical difference between the two groups in the detection rate of tumors in the simple metastatic area (2.94% and 2.59%, p=0.059) (Table 1). The positive screening rates for prostate cancer in patients with PSA 4-10 μg/L were 12.5% and 3,45% (p=0.0007) in the saturation puncture and 14-needle groups, respectively, and 36.03% and 13.79% (p=0.0008) in those with 10-20 μg/L, which were statistically significantly different (Table 2). There was no statistical difference between the two groups in terms of post-puncture complications, such as urinary retention, urinary tract infection and sarcoid hematuria. 3, Discussion In 1989, Hodge reported the technique of 6-stitch prostate puncture biopsy under ultrasound guidance via rectal pathway, which brought prostate puncture biopsy into the era of systematization and standardization. Since then, the puncture protocol has been improved and the positive rate of prostate cancer screening has been increasing. The transrectal prostate puncture biopsy is the most commonly used biopsy route in clinical practice, but it is often associated with the possibility of infection; moreover, for larger prostates, the ventral and apical parts of the prostate are limited, and there is often a risk of missing prostate cancer. The trans-perineal approach to prostate biopsy has no blind spots in the sampling of prostate tissue and is not affected by the volume of the prostate. The authors have compared the 14-stitch transperineal prostate puncture biopsy with the 12-stitch transrectal puncture biopsy, and the positive rate of prostate cancer screening was approximately equal between the two (p=0.082); in the transperineal puncture group, there was one tumor in the metastatic area and two in the apical prostate, and the incidence of carnal hematuria and urinary tract infection after the transperineal puncture operation was significantly lower than that of the transrectal puncture group. The rate of positive prostate cancer screening increased with the increase in the number of prostate puncture biopsy sites, and the Gleason score was more accurate in predicting tumors. The positive screening rate for prostate cancer ceased to increase when the number of puncture sites was greater than 22, and Stewart suggested that increasing the number of prostate puncture biopsy sites to ≥ 22, with corresponding biopsy sites in all parts of the prostate, could be called the saturation needle biopsy technique. The average PSA was 9.0 μg/L (6.1-12.0 μg/L) in 143 patients with previous negative biopsies who underwent a 24-stitch saturation needle biopsy. Zaytoun used a 24-needle transrectal biopsy, which was performed with a PSA density of 3.0 μg/L (6.1-12.8 μg/L) and a positive screening rate of 28%. Prostate saturation aspiration biopsy was used to screen patients with previous negative biopsies, and the positive prostate cancer screening rate was 32.7%, which was better than the 14-stitch protocol (29.7%). In this study, the positive prostate cancer screening rate in the 24-stitch saturation puncture group reached 48.53%, and the positive specimen rate was 8.09%, which was better than that of the 14-stitch group at 17.24% and 2.83% (p=0.0007 and 0.012). The positive rate of prostate cancer screening was significantly increased by the 24-stitch saturation puncture method. The 24-needle saturation puncture was significantly better than the 14-needle group in the PSA 4-10 μg/L and 10-20 μg/L groups (p=0.0007); for patients with PSA density <0.2, there was still a satisfactory positive rate of prostate cancer screening. Compared with the traditional transrectal pathway prostate puncture biopsy and the transperineal 14-stitch protocol, the 24-stitch prostate saturation puncture method in this group enhanced the sampling of the apical region of the prostate (8 stitches), with a positive rate of 11.76% for apical tumors, significantly higher than that of the 14-stitch group (1.72%). Because of national differences, there is a considerable degree of impediment to choosing a second prostate puncture biopsy in the country, so improving the accuracy of the first prostate puncture screening as much as possible is an important issue for urologists. The incidence of prostate cancer occurring in the metastatic zone alone is rare and often overlooked; Pelzer reported a 1.8% incidence of metastatic prostate tumors alone, suggesting that biopsy screening of the metastatic zone of the prostate is not routinely necessary. The incidence of tumors in the metastatic area of the prostate was 24% in McNeal's study, and the sampling of tissue from this area should be enhanced; Zhu reported that the incidence of metastatic prostate cancer alone was 12.5% in a population with TPSA 10.26C33.20 μg/L in China. In this study, the two trans-perineal prostate puncture protocols had positive screening rates of 2.94% and 2.59% for patients with PSA <20 μg/L and 8.09% and 6.90% for patients with tumors in the metastatic region combined with tumors in the peripheral region, which did not reach statistical differences. Compared with transrectal prostate puncture biopsy, transperineal prostate puncture biopsy reduces prostatic metastasis of bacteria in the rectum due to its relatively "clean" route, which theoretically reduces the chance of urinary tract infection after puncture. The probability of urinary retention was slightly higher than that of the transrectal route. In this study, the incidence of urinary retention was 9.56% and 9.48% in the 24-stitch saturation puncture group and the 14-stitch group, respectively, and there was no difference between them. One patient in both groups developed urinary tract infection after puncture, so 24-stitch saturation prostate puncture biopsy did not increase the incidence of urinary retention and urinary tract infection, although it increased the number of prostate puncture sites. In addition, trans-perineal pathway puncture biopsy allows clear visualization of the urethra under ultrasound, avoiding the occurrence of visual hematuria due to urethral puncture injury. In order to clarify the advantages and disadvantages of both in terms of complications, the sample size should be further increased for in-depth study. In conclusion, compared with 14-stitch trans-perineal prostate puncture biopsy, 24-stitch trans-perineal prostate saturation puncture biopsy significantly increased the positive screening rate for prostate cancer in patients with PSA <20 μg/L, especially in the apical region of the prostate, without increasing the incidence of associated complications.