Tumor biopsies do not cause cancer to spread to other parts of the body, a new Mayo Clinic study finds, dispelling a common myth that says otherwise. The study of more than 2,000 patients demonstrated that those who received a biopsy had a better outcome and longer survival than patients who did not have a biopsy.
The researchers studied pancreatic cancer, but the findings likely apply to other cancers because diagnostic technique used in this study — fine needle aspiration — is commonly used across tumor types, says the study’s senior investigator and gastroenterologist Michael Wallace, M.D., M.P.H., professor of medicine. The team’s findings are published in the Jan. 9 online issue of the journal Gut.
Fine needle aspiration is a minimally invasive technique that uses a thin and hollow needle to extract a few cells from a tumor mass. A long-held belief by a number of patients and even some physicians has been that a biopsy can cause some cancer cells to spread.
While there have been a few case reports that suggest this can happen — but very rarely — there is no need for patients to be concerned about biopsies, says Dr. Wallace. “This study shows that physicians and patients should feel reassured that a biopsy is very safe,” he says. “We do millions of biopsies of cancer a year in the U.S., but one or two case studies have led to this common myth that biopsies spread cancer.”
Biopsies offer “very valuable information that allow us to tailor treatment. In some cases, we can offer chemotherapy and radiation before surgery for a better outcome, and in other cases, we can avoid surgery and other therapy altogether,” Dr. Wallace says. Surgery for pancreatic cancer is a very big operation, and “most people should want to make sure they have cancer before they undergo surgery,” he adds.
He cites a previous study that found that 9 percent of patients who underwent surgery because of suspected pancreatic cancer actually had benign disease — an outcome that might have been preventable with preoperative tumor biopsy.
Biopsies associated with better survival rates
Dr. Wallace and his team have conducted two separate studies to examine the risk of biopsy.
In a 2013 study published in Endoscopy, the researchers examined outcomes in 256 pancreatic cancer patients treated at Mayo Clinic in Jacksonville, Florida. They found no difference in cancer recurrence between 208 patients who had ultrasound-guided fine needle aspiration (EUS-FNA) and the 48 patients who did not have a biopsy.
In the current study, they examined 11 years (1998-2009) of Medicare data on patients with non-metastatic pancreatic cancer who underwent surgery. The researchers examined overall survival and pancreatic cancer-specific survival in 498 patients who had a biopsy and 1,536 patients who did not.
During an average follow-up time of 21 months, 285 patients (57 percent) in the biopsy group died, compared to 1,167 patients (76 percent) in the non-biopsy group, the researchers found. Pancreatic cancer was identified as the cause of death for 251 patients (50 percent) in the biopsy group and for 980 patients (64 percent) in the non-biopsy. The biopsy group also had a longer median overall survival time than the non-biopsy group — 22 months compared to 15 months. Keep in mind that pancreatic cancer is one of the deadliest types of the disease; less than 5 percent of patients still alive five years after diagnosis.
While these results certainly seem to suggest that tumor biopsies are largely safe and effective, it should be noted that the researchers did not directly measure the spread of cancer cells. Rather, they used survival as a proxy measure for cancer spread, hypothesizing that “if tumor cell dissemination occurs with EUS-FNA, survival after complete resection would be impaired.”
It is unclear if survival is a valid indicator of tumor spread. However, given that death is the primary concern associated with the spread of cancer, these findings do address the most clinically significant outcome. What’s more, the results not only appear to refute the suggested link between biopsies and cancer spread, but they actually show that patients who undergo biopsies survive longer, on average, than patients who don’t. This is likely because biopsies allowed doctors to design better, more effective treatments for those patients, the researchers note.
“Biopsies are incredibly valuable,” Dr. Wallace says. “They allow us to practice individualized medicine — treatment that is tailored for each person and designed to offer the best outcome possible.”