Patient preparation

Informed consent is obtained from the patient before TRUS-

guided biopsy. A DRE should be performed to rule out any anal and rectal pathology that may preclude insertion of the ultrasound probe. One study found that bacteremia and bacter-iuria occurred in 44% and 16% of men, respectively, following TRUS-guided biopsy of the prostate. In one double-blind, randomized controlled trial,78 prophylactic antibiotic administration significantly reduced the complications of fever and urinary tract infection compared with placebo. More than two doses of a fluoroquinolone antibiotic can also significantly decrease the infection rate,79 which can be as low as 1.7% when antibiotics have been administered.80 Therefore, it appears prudent to administer antibiotic prophylaxis for this procedure, with treatment begun before biopsy and continuing for 24-48 hours following biopsy. Hematuria, the most common complication, usually is minor and resolves spontaneously. To be prudent, platelet-inhibiting medications should be discontinued 7 days prior to the procedure. Although mechanical bowel preparation does not seem to be necessary to decrease significant clinical complications, we routinely administer a Fleet enema, while others81 suggest it may not be necessary.

It has been demonstrated using a prospective randomized double-blind study that TRUS-guided prostatic nerve blockade can significantly reduce the discomfort experienced with TRUS-guided prostate biopsies.82 The local anesthetic used was 5 ml of 1% lidocaine injected with a 7-inch 22-gauge spinal needle under TRUS guidance into the region of the prostatic vascular pedicle at the base of the prostate, just lateral to the junction between the prostate and seminal vesicle. This local anesthetic treatment may become increasingly important to patients who undergo the extended biopsy schemes. Another more recent report, however, did not confirm these findings.

Sextant and digital directed

Digitally directed biopsies have been shown to be inferior to TRUS-guided biopsies.83 Systematic sextant biopsy of the prostate under TRUS guidance was first shown to outperform directed biopsies in 1989 and has significantly affected our ability to detect prostate cancer.84 The sextant biopsy strategy involves obtaining biopsies in the midsagittal plane from the base, midgland and apex of both sides of the prostate from the peripheral zone. If a hypoechoic lesion is visualized, it is targeted and the biopsy needle is directed through the widest diameter of the lesion as determined on the TRUS.

Extended strategies

In 1995, it was recommended that utilizing the sextant biopsy method but directing the biopsies in a more lateral direction would enhance the cancer biopsy yield.85'86 Subsequently, it was observed that the sextant biopsy strategy missed 15% of prostate cancers compared with a more extensive biopsy strategy involving additional biopsies of both hypoechoic lesions as well as irregular echogenic lesions with an indistinct border between the peripheral and transition zones.87 In this same study, an additional 8-10 systematic biopsies were taken, depending on the gland size. An immediate set of repeated sextant biopsies in a single office visit can also increase the number of prostate cancers detected by 30%.88 Other investigators have observed prostate cancer detection rates in the range of 23-26% in men undergoing repeated biopsies using the sextant strategy.89-91 Furthermore, a five-region prostate biopsy strategy that included far lateral and mid-region biopsies also detected more prostate cancers than did the standard sextant technique.92 This extended biopsy strategy did not result in any significant increase in morbidity.

Studies targeting the transition zone, where approximately 20% of prostate cancers originate, have been performed. The addition of transition zone biopsies to an initial biopsy strategy increased detection rates by only 1.8-4.3%.93-95 Routine biopsies of the transition zone for prostates larger than 50 cm3 increased detection by 13%.96 The reported incidences of positive results for transition zone biopsy in men undergoing repeated biopsy range from 10% to 13%.97,98

Further data have found that, in addition to the number of biopsies, the exact location of the biopsies in the prostate affects the cancer detection rate, regardless of gland size. Chen etal.99 observed that an 11-core multisite-directed biopsy

Endometrial Biopsy Prep

Fig. 14.1. The 11-core biopsy scheme includes the conventional sextant biopsies, two anterior horn biopsies (one each from the left and right sides of the prostate), two transition zone biopsies just lateral and anterior to the urethra (one each from the left and right sides of the prostate), and one midline biopsy. Reprinted with permission from Babaian etal. (2000).100

Fig. 14.1. The 11-core biopsy scheme includes the conventional sextant biopsies, two anterior horn biopsies (one each from the left and right sides of the prostate), two transition zone biopsies just lateral and anterior to the urethra (one each from the left and right sides of the prostate), and one midline biopsy. Reprinted with permission from Babaian etal. (2000).100

technique performed the best when a number of biopsy schemes were compared using computer simulation.99 This 11-core biopsy scheme included the conventional sextant biopsies, two anterior horn biopsies (one each from the left and right sides of the prostate), two transition zone biopsies just lateral and anterior to the urethra (one each from the left and right sides of the prostate) and one midline biopsy (Fig. 14.1). This 11-core biopsy scheme improved cancer detection rates and correlated better with the tumor volume found in the radical prostatectomy specimen. In addition, a comparative analysis of this 11-core multisite-directed biopsy strategy versus the sextant method found that prostate cancer detection was significantly enhanced and that the anterior horn area in the peripheral zone was the most frequently positive site.100 Presti et al.101 concluded that a six-sample systematic biopsy strategy of the peripheral zone is inadequate and that a minimum of eight biopsies (including the apex, midlobar midgland, lateral midgland and lateral base) should be routinely performed to optimize the detection rate. Improved detection has also been described using a saturation biopsy technique whereby 14-45 biopsies were performed in men with previous negative biopsy results.102 These investigators demonstrated that the number of previous negative biopsies was not predictive of subsequent cancer detection and prostate cancer was detected in 34% (77 out of 224) of patients. Over 85% of these prostate cancers were considered clinically significant.

Factors that may affect the number of biopsy cores

The question of whether the number of biopsies should be varied based upon the volume of the prostate remains unanswered. Even more specifically, the question of whether to perform more biopsies of the transition zone based upon volume estimates of this region of the prostate also remains unanswered. Cancer detection rates of 38% were achieved using sextant biopsies when the prostate volume was less than 50 cm3.103 An inverse relationship between prostate volume and yield of sextant biopsy has also been observed by others.104 Using Bayer's conditional probability theorem, Stricker etal.105 determined that to achieve a detection rate sensitivity of 95%, a cancer would have to occupy 40% of the gland volume to be detected by six biopsies. This level of sensitivity could be attained for prostate cancers occupying only 15% of the prostate, if 18 biopsies were performed.105 In a retrospective study, Chen etal.106 observed a significant (P=0.03) association between tumor volume and prostate size (0.5 cm3 or less prostate cancers were twice as frequent in prostate glands greater than 50 cm3). In this study, 39% of all prostate cancers with a volume of 0.5 cm3 or less occurred in prostates that were larger than 50 cm3, and only 18% of all prostate cancers larger than 0.5 cm3 occurred in prostates larger than 50 cm3. They concluded that biopsies in men with prostates larger than 50 cm3 were driven by an elevated serum PSA that was secondary to benign prostatic hyperplasia and that the lower cancer detection rate in larger volume prostates was a consequence of the higher proportion of small volume cancer in these glands.106 This study implied that large prostates are more likely to be biopsied because of an elevated PSA concentration resulting from benign prostate tissue and not from a significant prostate cancer and that increasing the number of biopsies to compensate for incresed prostate volume runs the risk of increasing the detection of clinically insignificant tumors. Whether the improved detection rates provided by alternate biopsy strategies will result in better patient outcome awaits the results of prospective trials.

In summary, there are no definitive data that ultimately support efforts to screen for prostate cancer in order to improve survival. However, there are detection modalities that appear to optimize the detection of organ-confined prostate cancer. DRE and PSA appear to be adequate and the most cost-efficient screening tests. A number of PSA indices may improve our specificity in detecting prostate cancer, but currently only % free PSA has been accepted for widespread clinical use for this purpose. There is a potential role for complexed PSA. There are multiple biopsy strategies, and the results of comparative studies indicate that detection rates can be significantly improved utilizing directed biopsies and utilizing more than a six-sample systematic biopsy technique. The ultimate biopsy strategy has not been determined but an extended schema without transition zone biopsies is strongly recommended for an initial biopsy. Biopsy strategies will likely be further refined and individualized based upon whether a man is undergoing an initial or repeat biopsy and upon the total PSA, % of PSA isoforms, DRE findings, TRUS findings, age and ethnicity.100'107 The reader is urged to read the screening algorithm recommended by the National Cancer Center Network.108 This algorithm represents a consensus of the participating institutions and is updated annually.

Was this article helpful?

0 0
Sleeping Solace

Sleeping Solace

How To Better Your Sleep For A Better Life. Understanding the importance of good sleeping habits is very beneficial to the overall health of an individual in both mental and physical levels. Learn all the tricks here.

Get My Free Ebook


Post a comment