Every year, more than 1 million men in the United States undergo a prostate biopsy to check for cancer, but one in 20 will develop an infection in the process. Doctors typically prescribe antibiotics to prevent that, but infection rates have been climbing for more than a decade.
That’s led to a host of new strategies and techniques aimed at preventing infection or reducing the need for biopsies.
“Whenever something bad happens to a patient, it hits me particularly hard,” said Dr. Matthew Simmons, a urologist with Bend-based Urology Specialists of Oregon, who published his strategy in a prominent urology journal last year. “I just got sick of seeing it.”
In a standard biopsy, doctors use ultrasound imaging to guide a needle through the rectum and into the prostate gland, taking about a dozen tissue samples to check for cancer. The rectum, however, is full of bacteria, which can hitch a ride on the needle and make its way into the prostate, the bladder or the bloodstream.
According to the American Urological Association, 5 to 7 percent of men undergoing prostate biopsy will develop an infection, and 1 to 3 percent will need to be hospitalized at an average cost of $4,000 to $5,000. In rare cases, it can lead to bloodstream infection known as sepsis that can be fatal.
Typically, doctors have prescribed antibiotics from a category known as fluoroquinolones, that include the drug ciproflaxin, sold under the brand name Cipro. But one in five men harbor bacteria that is resistant to that group of antibiotics, which increases their risk for a post-biopsy infection four-fold. That has led to an increase in the infection rate.
Researchers from Weill Cornell Medical Colleges reported in 2016 that infection rates within 30 days of prostate biopsy in New York increased from 2.6 percent in 2011 to 3.5 percent in 2014.
“Antibiotics are widely used in the food supply in this country. There’s overprescribing of antibiotics for upper respiratory infections and other conditions,” said Dr. Stacy Loeb, a urologist with New York University’s Langone Health in New York City. “There’s just a great prevalence of antibiotic resistance, which has very little to do with prostate biopsy per se.”
Loeb said urologists are trying to screen patients for infection risk factors, including things like uncontrolled diabetes, exposure to antibiotics, recent international travel or hospitalization. Patients at higher risk can be given additional antibiotics. In some cases, doctors will perform a rectal swab a few days before the biopsy to check for resistant bacteria. Studies have shown those approaches haven’t been that effective in preventing infections.
Simmons and his colleagues developed a protocol that includes a different combination of antibiotics, as well as disinfecting the biopsy needle with alcohol after each sample is taken. The change in antibiotics reduced the clinic’s infection rate from about 4 percent to 2 percent. Adding the needle washing component drove the infection rate down to zero.
“Now, we’re up to 481 consecutive biopsies without an infection,” Simmons said. “It’s one of those things that works for us, but you have to wait for other centers to try it and publish their data to determine whether it’s real.”
Other researchers have tried needle cleaning with formaldehyde or iodine, or wiping down the needle with an alcohol sponge, with mixed results. Simmons believes his technique might be more effective because he doesn’t just clean the exterior of the needle.
“I think the inside of the needle is where all the junk is trapped,” he said, “and every time you fire that needle into the prostate, you’re basically inoculating that person with the stuff that’s inside the needle.”
Other doctors have advocated for avoiding the rectal approach and going through the perineum, the area between the rectum and the scrotum. The transperineal approach has infection rates close to zero, but has other disadvantages. For one, that technique is generally done in an operating room or surgery centers under anesthesia, which brings added costs and risks. It’s also a trickier procedure to pull off, raising the question of whether it is as good at finding cancer as the traditional approach.
“In experienced hands, transperineal does an equal job of detecting cancer as transrectal, but a lot of urologists haven’t been trained that way,” said Dr. Sudhir Isharwal, an assistant professor of urology at Oregon Health & Science University. “It has been gaining traction, especially for patients who need repeated biopsies.”
New recommendations on prostate cancer screening in 2012 have led to a 20 percent reduction in diagnostic biopsies in the U.S. and Canada. Some of the decline, however, has been offset by an increase in active surveillance of low-risk prostate cancer, which often relies on repeated biopsies. Doctors are working on ways to reduce the need for biopsies, especially repeated biopsies, with more advanced testing and MRI imaging.
Patients diagnosed with prostate cancer who choose active surveillance rather than surgery or radiation once routinely got biopsies every one or two years. Now, patients at OHSU follow-up with an MRI after a year, and if the lesion hasn’t changed, will shift to a two- to four-year interval between biopsies.
MRI imaging has also allowed doctors to reduce the number of samples taken per biopsy.
“We used to take 24 cores, 18 cores,” Isharwal said. “Now with MRI, we can take only three cores from the target and find equivalent cancer detection.”
Loeb said efforts to reduce biopsies are probably the main area of research in the field now. Doctors used to rely on PSA blood tests to determine whether a patient might have prostate cancer and whether to do a biopsy.
Better tests limit the false alarms. Combined with better imaging and risk stratification, doctors can feel more confident about the patient’s cancer risk without getting a prostate tissue sample and putting the patient at risk of an infection.
“The hope is to reduce the total number of biopsies being done in the first place,” she said.
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