Template biopsy for prostate cancer

A template biopsy is a different way of assessing the prostate compared with the standard prostate biopsy. It is beneficial in two circumstances:

1. For men known to have prostate cancer and who are trying to choose between either having immediate curative treatment or careful monitoring with delayed curative treatment if the disease progresses
2. For men who have had repeated negative biopsies but a high PSA reading and are therefore considered to be at high risk of having prostate cancer

Why might template biopsies help when deciding what treatment to have?

Some men may have the type of prostate cancer that does not need treatment either at all or for many years. However, trying to decide whether or not this is true can be very difficult because traditional biopsies only sample a small amount of the prostate. Template biopsies examine every part of the prostate evenly, including areas that cannot be biopsied by the standard technique through the back passage (ie “transrectal”). When the results of template biopsies come through, we will know if there is prostate cancer present that usually needs treatment now, or if it is possible to avoid treatment altogether. This means we can personalise the treatment for every man.

What is a ‘false negative’ and why is a standard biopsy not always accurate?

For the majority of patients, the standard biopsy, known medically as a TRUS biopsy, remains an accurate way of diagnosing prostate cancer. However between 10 and 30 per cent of patients will be given what is called a ‘false negative’ result. This means their biopsy result is negative, however prostate cancer is in fact present; it simply has not been detected during the biopsy.

The high false negative rate occurs because of the imprecise nature of the standard TRUS biopsy. It involves inserting an ultrasound probe into the back passage (rectum). A needle is then placed down through the shaft of the probe, through the wall of the rectum and into the prostate.

The procedure takes place under the guidance of the ultrasound image on a screen. Although this image helps to visualise the prostate, it lacks detail and precision. Needles are inserted in six to 12 different places, with the aim of ensuring all areas of the gland are sampled. Even in experienced hands, it is inevitable that for some patients, the needle will miss the cancerous sections of the prostate.

How does a template biopsy work and why is it beneficial?

The term ‘template’ refers to a plate which was developed to provide precise and accurate mapping of the prostate. It was originally developed for a procedure called brachytherapy, in which needles are inserted through holes in the template to exactly position radioactive seeds within the prostate.

By using this same template during a biopsy, the urologist is able to accurately map where each tissue sample is taken in a systematic way to ensure every section of the prostate is sampled. Contrastingly, during a standard biopsy, it is possible that cancerous tissue is missed from the normal 12 tissue samples taken.

The template biopsy is also carried out at a different angle to the standard biopsy, sometimes called the TRUS biopsy. The needles are inserted through the perineum (the area between the scrotum and anus) which means there is less chance of infection for the patient compared with the TRUS biopsy and there is less discomfort because it is done under a general anaesthetic.

The angle of a template biopsy also allows for improved sampling of the central and anterior sections of the prostate than a TRUS approach. The anterior section of the prostate is particularly difficult to assess and is an area where prostate tumours have traditionally been missed. It is important to note that template biopsy is not usually the first line diagnostic test for prostate cancer. For the majority of patients, a TRUS biopsy will be an effective diagnostic tool. But for those high risk patients with repeated negative tests, template biopsy offers an important and valuable new method for assessing prostate cancer.

What evidence is there that template biopsy is effective?

Template biopsy was first introduced in America and is gradually being introduced in a small number of specialist urological centres now in the UK. Evaluations of its effectiveness are very promising. One study, entitled Evaluation of a novel precision template-guided biopsy system for detecting prostate cancer¹ involving 140 patients concludes: “Template-guided biopsy potentially produces a higher cancer detection rate and more accurate assessment of grade.”

Notes

[1] Study authors: Ifeanyichukwu I. Megwalu, Genoa G. Ferguson, John T. Wei , Vladimir Mouraviev , Thomas J. Polascik, Samir Taneja, Linda Black, Gerald L. Andriole and Adam S. Kibel Division of Urology,  Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, Department of Urology, University of Michigan School of Medicine, Ann Arbor, MI, Division of Urology, Duke University School of Medicine, Durham, NC, and Department of Urology, New York University School of Medicine, New York, NY, USA