For American men, prostate cancer is the most common type of cancer, with 200,000 new cases diagnosed last year. The only way to definitively confirm the presence of cancer is by biopsy of the prostate. While it is widely recommended for men who are suspected of having the disease, stories have turned up in the media suggesting that prostate biopsies carry the risk of spreading cancer cells, increasing the likelihood of recurrence. Could the very test that diagnoses prostate cancer cause its spread? I posed this question to J. Stephen Jones, MD, who is the chairman of the department of regional urology at the Cleveland Clinic Glickman Urological and Kidney Institute and author of The Complete Prostate Book.
The possibility that a man might have prostate cancer is first identified through early detection tests such as the prostate-specific antigen (PSA) blood test and a digital rectal exam (DRE). If either suggests the possibility of prostate cancer, a prostate biopsy is the next step, says Dr. Jones. In the US, this is most commonly done with an ultrasound probe placed in the rectum and a core needle biopsy. Guided by the probe, the doctor inserts a narrow needle through the rectal wall into the prostate gland. When the needle is pulled out, it removes a sample of tissue. Usually performed under general anesthesia, this process is typically repeated 10 to 12 times or more in order to obtain tissue from different parts of the prostate.
Regarding this frequently asked question about spreading prostate cancer, Dr. Jones maintains that needle biopsy does not pose significant risk. “This is primarily based on old wives’ tales,” he said. “Since metastasis occurs when cells break off and spread through the bloodstream, it makes sense that a needle placed through cancerous tissue might break off some cells. But in fact, this occurs only rarely, with certain types of high-grade cancers such as kidney cancer. Prostate cancer is not one of those types.” Dr. Jones told me that he does not know of a single case reported where this occurred following a transrectal biopsy.
On the other hand, there is another type of biopsy for prostate cancer called a transperineal biopsy, that in a very few instances, has been associated with cases of spreading cancer, Dr. Jones acknowledged, noting that this is rare. “The only data that has ever shown that a prostate biopsy may pose a risk are associated with transperineal biopsies, in which tissue is collected by a thin needle that is inserted through the skin between the scrotum and rectum and into the prostate,” explained Dr. Jones. This procedure is more common in Italy, where there have been occasional reports of needle tracking cancer spread. Some doctors believe this type of biopsy provides better information on the location of the cancer than the transrectal approach, but this is controversial, Dr. Jones said. While the transperineal approach remains very uncommon in this country, Dr. Jones said this procedure may be seeing a small resurgence in the US based on this potential benefit.
In contrast, transrectal biopsies are considered generally quite safe and effective for diagnosing prostate cancer, with few associated risks, and even those occurring in only about 1% of patients. The most common associated problems include blood in the rectum or urine that lasts for a few days or blood in the semen for a few weeks. More significant risks include heavy bleeding in urine/stool, urinary retention and infection.
A prostate biopsy should be performed by a urologist, not a family practitioner or internist. Also, suggested Dr. Jones, be sure to ask your urologist about the number of core samples to be taken. He said research indicates the importance of sampling at least eight to 10 cores. “Less than that, one has a significant chance of missing cancer, and it may mean, frankly, that the doctor hasn’t kept up with the latest understanding of biopsy procedures,” he said.
Dr. Jones states that all forms of prostate biopsy are highly accurate, especially if the results are positive. If biopsy results are negative, however, there is a one-in-four risk that a small tumor may have been missed, he notes. So men must continue to be on alert and should be checked regularly.
