How important is electronic tumor tracking?

This report discusses using a device to track tumor sites in follow-up biopsies in prostate cancer. 

Biopsies (the removal of tissue from the body and examination to establish the presence of cancer) are a very important part of active surveillance (patient monitoring instead of treatment) in early prostate cancer. They are usually carried out using transrectal ultrasound imaging (TRUS), which is used to capture images and tissue samples from the prostate. However, this approach may not capture samples from the same tumor site upon re-sampling and may lead to an inaccurate representation of the progression or stability of the cancer.

A new biopsy-tracking device using magnetic resonance ultrasound fusion (MRSU) has been developed called Artemis. This involves using magnetic resonance imaging (MRI; a method of imaging) to create an image of the prostate and guiding the needle during prostate biopsy to areas of interest (where cancer is suspected following MRI) which can then be ‘tagged’ so that they are easier to find at subsequent biopsies.

The authors of this article aimed to evaluate the ability of the Artemis device to perform follow-up biopsies in sites that had previously tested positive for cancer.

53 men were used in this study. They received a biopsy (biopsy 1; undertaken 6 months after TRUS-guided biopsy) of the prostate cancer site using Artemis and then a further follow-up biopsy (biopsy 2). Biopsy 1 involved sampling 12 sites of the prostate that were tagged as ‘regions of interest’ by MRI in an effort to make re-sampling easier. Artemis biopsy 2 was carried out 11 months later and sampled any sites that were positive for cancer in biopsy 1.

74 cancer sites were found and tagged in biopsy 1 – 85% had a Gleason score (from 2-10; defines how different the cancer cells look from normal cells and how likely it is that the tumor will spread) of 6 while 15% had a score of 7.

In biopsy 2, cancer was found in 39% of these tagged sites. Of these, 49% had aggressive prostate cancer. Of those sites that had a Gleason score of 6 at biopsy 1, 62% did not have cancer or still had a score of 6 while 14% had an increased Gleason score at biopsy 2. Of those with Gleason score 7 in biopsy 1, 44% had cancer at biopsy 2, of which 60% had been downgraded (cancer had improved).

Where the cancer core length (CCL- length of tumor) was < 1mm in biopsy 1, only 14% of sites had cancer in biopsy 2. Where the CCL was > 2mm in biopsy 1, 53% of sites in biopsy 2 contained cancer. When CCL was > 4mm in biopsy 1, 71% contained cancer in biopsy 2.

When these sites were MRI areas of interest and had a CCL > 4mm in biopsy 1, 83% showed cancer in biopsy 2. The grade as determined by MRI on biopsy 1 was the greatest predictor of the presence of cancer at biopsy 2 (higher grade defined by MRI was associated with 48% increased likelihood of finding cancer at the same site at biopsy 2).

Electronically tracking biopsies is important in patient surveillance and could improve detection or classification of cancer in repeat or follow-up biopsies.

This study did not include a control group and long-term outcomes are unknown so accurate tumor tracking over an extended period cannot be concluded.

If you are concerned with the accuracy of your current testing methods, discuss your options with your doctor.