Prostate biopsy for prostate cancer

Before the onset of the PSA method, a biopsy of the prostate gland was performed only to clarify the diagnosis and the purpose of hormonal therapy in case of palpable detection of changes in the gland or metastases of prostate cancer.

Currently, early diagnosis can detect localized forms of prostate cancer and carry out radical treatment, so the biopsy is expected to receive additional information influencing the choice of the method of treatment.

[1], [2], [3], [4], [5], [6]

Types of prostate biopsy

The main method of performing a biopsy is multiple puncture biopsy of the prostate under the control of transrectal ultrasound with a needle of 18 G. When carrying out concomitant antibacterial therapy, the risk of complications is small. Performing a biopsy needle 14 G is fraught with a high risk of infectious complications and bleeding.

About 18% of prostate cancer is diagnosed by the detection of palpable prostate formation. At the same time, in 13 -30% the level of PSA is from 1 to 4 ng / ml. When palpation of the node in the gland, a targeted biopsy is recommended. The sensitivity of the biopsy, conducted under the control of duplex ultrasound with contrast, is not inferior to the sensitivity of multiple biopsies. Nevertheless, this method of research has not yet received general recognition.

According to studies, with a PSA content of about 4-10 ng / ml, cancer is confirmed only in 5.5% of cases. At simultaneous carrying out of a primary biopsy this parameter increases up to 20-30. Relative indication for biopsy - lowering the threshold level of PSA to 2.5 ng / ml. During a sextant biopsy with a PSA level of 2.5-4 ng / ml, detection of prostate cancer is 2-4%, but with an extended biopsy technique (12-14 junctions) it increases to 22-27%. It should be noted that in 20% of cases latent cancer is detected (tumor volume less than 0.2 cm ³ ). Thus, a decrease in the upper limit of the PSA standard leads to the detection of clinically insignificant tumors that, without treatment, would not threaten life. In order to establish the upper limit of the PSA norm, which allows finding nonpalpable, but clinically significant tumors, the data is still insufficient. When determining relative indications, it is necessary to take into account other parameters of PSA (increment, doubling time, etc.). Increasing the upper limit of PSA, which requires a biopsy, is irrational, since there is a high probability of detecting prostate cancer. Only at the age of over 75 did it become possible to raise the upper threshold to 6.5 ng / ml.

Sight biopsy of the prostate gland is necessary only with palpable tumor and PSA level of more than 10 ng / ml. In order to clarify the diagnosis in a metastatic or locally advanced process, it is sufficient to obtain 4-6 biopsies. In other cases, multiple biopsies are recommended.

In the last 15 years the technique of biopsy, proposed by K.K. Hodge et al. (1989). Its essence is in taking biopsies in the middle distance between the medial groove and the lateral border of the prostate gland from the base, middle part and tops of both lobes, in connection with which the technique was called a sectar (6-point) biopsy. The 6-point biopsy method was further improved in such a way that posterolateral sections of the peripheral zone of the gland would fall into the biopsy specimens, which are unavailable in the standard technique. In addition, as the prostate volume increases, the incidence of cancer detection with the use of the sectarian technique is reduced. The required number of tissue samples requires specification. In almost all studies, an increase in the number of biopsies increased the sensitivity of the method (compared to a 6-point biopsy). The biopsy sensitivity is higher the more the number of biopsies is investigated. In the tests on the models of the gland, it is established that if the tumor volume is 2.5, 5 or 20% of the gland volume, then in a sectarian biopsy the tumor is diagnosed in 36, 44 and 100% of cases. When performing a biopsy, it should be borne in mind that in 80% of cases the tumor appears in the peripheral zone. According to one of the studies, taking 13-18 biopsies increased the sensitivity of the method by 35%. The normograms of Vienna (2003) reflect the relationship between the number of injections, the age of the patient and the volume of the prostate. At the same time, the forecast accuracy is 90%.

Dependence of the number of biopsies on the patient's age and prostate volume with an accuracy of a positive predictive prediction of 90%

Age, years	Prostate volume, ml
	<50	50-60	70	> 70
20-29	6th	8	8	8
30-39	6th	8	10	12
40-49	8	10	12	14
50-59	10	12	14	16
69	12	14	16	-
> 70	14	16	18	-

It has been proved that it is not advisable to capture the transitional zone of the gland during primary biopsy, since it is very rare in cancer (less than 2% of cases). Currently, the most common 12-point biopsy. Great importance is attached not only to the number of jabs, but also to the inclination of the needle.

Biopsy for prostate cancer

In the histological conclusion, the following positions must be reflected:

• localization of biopsy specimens; is especially important in the planning of radical prostatectomy; the prevalence of the tumor per one or both parts is taken into account when performing a nerve-sparing operation; when the top of the gland is affected, the stage of its mobilization is more complicated; the probability of a positive surgical margin is high when the sphincter of the urethra is allocated;
• orientation of the biopsy specimen in relation to the glandular capsule; for clarification, the distal (rectal) segment is stained with a special solution;
• presence of IDUs;
• the amount of damage to the biopsy and the number of positive jabs;
• differentiation of tumor cells according to Gleason;
• extracapsular extension - detection in biopsy specimens of a capsule of the prostate, adipose tissue and germinating tumor tissue, which is important for choosing a method of treatment;
• perineural invasion, indicating the spread of the tumor beyond the prostate gland with a probability of 96%;
• vascular invasion;
• other histological changes (inflammation, prostatic hyperplasia).

If the above indicators are not reflected in the histological conclusion, then it is necessary to specify the location and the number of positive biopsies, as well as the degree of differentiation of the tumor according to Gleason.

[7],

Interpretation of biopsy data for prostate cancer

Interpretation of these biopsies requires an individual approach. If a negative result of the first biopsy requires a repeat biopsy, the probability of detecting cancer at the same time is 10-35%. In severe dysplasia, the probability of detection of cancer reaches 50-100%. In this case, it is necessary to conduct a repeated biopsy in the next 3-6 months. It is proved that two biopsies allow to detect the majority of clinically significant tumors. Even after taking a large number of biopsies and a negative result of the first biopsy, repeated biopsy often reveals cancer. If you suspect a prostate cancer, none of the methods of diagnosis does not provide enough sensitivity, which allows you to refuse a repeated biopsy. The cases of detection of a single hearth require special attention. Clinically insignificant cancer (tumor volume less than 0.5 cm ³ ) after radical prostatectomy is observed in 6-41% of observations. In this situation, the clinical situation should be comprehensively assessed and treatment tactics determined. The most important role is played by the age of the patient, the level of PSA, the degree of differentiation of the tumor, the amount of damage to the biopsy, the clinical stage. The presence in the biopsy of prostatic intraepithelial neoplasia (PIN) of high grade can indicate a malignant process in the prostate gland. Such a patient is shown a repeat biopsy after 3-12 months, especially if 6 biopsies were initially obtained. Indications for repeated biopsy - palpable formation in the prostate gland, increased PSA level and severe dysplasia with the first biopsy.