"Should I worry? The short answer is no."
First of all, there is no way of getting around a biopsy. There are side effects with any procedure but in order to properly treat a patient, a good biopsy specimen is absolutely critical. The benefit of being able to select the proper surgery and subsequent treatment clearly outweighs the risk.
That said, many women come to me concerned that their biopsy might have spread their cancer along the line where the needle traversed the breast (known as the needle tract). More cancer (or higher stage cancer) is often found when a woman has surgery after the biopsy and more tissue is removed. For this reason, it’s understandable to wonder whether the biopsy procedure itself actually caused the cancer to spread or progress further. On top of this, in other cancers such as testicular, doctors are taught never to biopsy the tumor with a needle because of concern it could seed the tumor along the needle tract, though this is unproven. The organ is simply removed whole.
"...[T]here is no solid evidence that biopsies can cause breast cancer to spread, and that’s one less thing to worry about."
So should you worry about this? The short answer is no. Let me explain.
The risk of “seeding the tract” is theoretical. It has never been proven in a strong, reliable, scientific breast cancer study. For sure, almost anything is possible and it is considered prudent by surgeons to use the shortest needle tract possible to get to the tumor for biopsy in order to lower this theoretical risk and to decrease the risk of other complications as well. But there is no reliable evidence that “seeding the tract” actually happens.
Can a biopsy turn DCIS into an invasive cancer?
Here too, the answer is no. Normal cells turn into DCIS, which then turn into invasive cancer by a process known as tumorigenesis. This is a complex, molecular change that occurs over many years and is not affected by a biopsy.
The only way to completely eliminate this theoretical risk would be to perform a mastectomy, where the entire needle tract (and breast) is removed. We know that women who have breast-conserving surgery with radiation (where the needle tract is mostly left in) do just as well as women who have mastectomy in terms of the cancer coming back. If the needle-tract risk was something to worry about (real or not), women with breast-conserving treatment would do worse — but this is not the case.
I care for patients with breast cancer every day. The amount of anxiety they are subject to is overwhelming. There are many real concerns for women that will impact their chance of being cured: getting the right diagnosis and treatment, side effect management, financial security, and follow-up. But there is no solid evidence that biopsies can cause breast cancer to spread, and that’s one less thing to worry about.
SOURCE: Dr. Brian Wojciechowski, M.D. in an article published for breastcancer.org on November 20, 2012.