Up till now, prostate cancer has been the only tumor cancer diagnosed by random luck. That’s right, random luck. The most common type of prostate biopsy is guided by transrectal ultrasound, or TRUS. It is considered the “gold standard” for prostate biopsy because it’s most widely used by urologists.
Being the most common doesn’t mean it’s the best. The tumor is not visible on ultrasound, so the doctor fires a number of needles in a systematic array, half on each side of the gland. Theoretically, the more needles used, the greater chance of capturing prostate cancer. Therefore, TRUS-guided biopsies have gone from 6 needles in the 1990s to today’s convention of 12-14 needles, or “extended array.”
Here are the five main problems with conventional TRUS biopsy:
- Blindfolded at a target range: TRUS does not detect and reveal the characteristics that separate healthy prostate tissue from prostate tumors—or even noncancerous conditions like BPH and infection. It is limited to the basics: the shape and size of the gland, and where the needles show up. In short, the doctor fires needles without being able to see the target.
- Sampling error: TRUS predictably misses or under-samples certain anatomic areas of the gland. TRUS biopsy tends to miss tumors at the front (anterior) of the gland, which is most distant from the rectal wall. It also under-samples the apex, or “tip” of the prostate furthest from the bladder. Because of this, studies show that 30% or more of cancers, especially in these areas, are missed in the first biopsy.[i]
- Repeat biopsies miss, too: If the first biopsy was negative but cancer is still suspected, using the same systematic array as the first time has approximately the same sampling error. The way doctors overcome this is to increase the number of needles, often to 20 or more cores. It’s not unusual to have a 3rd biopsy if the 2nd is negative, but meanwhile the undetected cancer continues to grow. Late detection can result in higher treatment failure rates.
- Oops, wrong cancer: There is ongoing discussion today about significant vs. insignificant prostate cancer. Most experts agree that insignificant (very low to low risk) cancer can be managed with Active Surveillance (AS) as a way to defer the side effect risks of treatment. A growing body of evidence suggests that TRUS biopsy over-detects insignificant cancer and under-detects significant disease. This means that thousands of low-risk patients have been sent for whole gland treatment on the theory that all prostate cancer is multifocal. In fact, at least a third of insignificant cancers qualify for AS or focal therapy. In other words, based on TRUS biopsy we have been guilty of treating the wrong cancer, leaving countless men with side effects like incontinence and ED.
- TRUS biopsy side effects: The more needles used, the greater the risk of biopsy side effects. These include pain or tenderness, infection (sometimes requiring hospitalization), blood in urine or semen, bleeding from the rectum, ED, lower urinary tract symptoms, including urinating often, weak or slow urine stream or dribbling urine.
MRI-guided targeted biopsy – the alternative to TRUS
If TRUS is so flawed, what should you do if your doctor says you need a biopsy? Fortunately, there is a better image-based approach to detecting and diagnosing prostate cancer: Multiparametric MRI.
The Sperling Prostate Center offers an expert alternative to TRUS in two simple steps.
- Multiparametric MRI (mpMRI) is a noninvasive, painless way to determine if prostate cancer is present. Using mpMRI, Dr. Sperling can determine if a biopsy is necessary because our powerful 3 Tesla (3T) magnet will reveal a suspicious lesion. It can show the size, shape, location of prostate cancer, and even give clues to how aggressive it is. If nothing shows up on the MRI, no biopsy is necessary; the patient can then be monitored by imaging.
- If a suspicious area is seen, Dr. Sperling can use real-time MRI to direct a minimal number of needles into the area. Unlike a 12-core blind biopsy, a real-time MRI biopsy takes precise samples from the core of the suspicious tumor, where the most aggressive cells are likely to be. This minimalist approach to a biopsy not only greatly reduces the risk of side effects and avoids repeat biopsy, but also gives the most accurate diagnosis of the tumor cells.
Skip the TRUS and go straight to mpMRI
If you are recommended for a prostate biopsy, do not be rushed into a TRUS procedure. Contact the Sperling Prostate Center to consult with one of our knowledgeable staff to help determine if mpMRI is the next right step for you.
[i] Serefoglu EC, Altinova S, Ugras N, Akincioglu E et al. How reliable is 12-core prostate biopsy procedure in the detection of prostate cancer? Can Urol Asso J. 2013 May-Jun;7(5-6): E293-E298.