Do biopsies accelerate cancers?

Question

Once seen on TV, a woman interviewed on why she avoids having a biopsy for her suspected cancer, claiming that a biopsy will only accelerate it, thus more dangerous than beneficial.

Searching for a source of such a claim, I've found this:

Sadly many have been led to believe that early cancer screening will save their lives, nothing could be further from the truth. In fact biopsies often are instrumental in seeding the cancer elsewhere in the body. Thus accelerating cancer growth (metastasis) that was once contained by body and may have been slow progressing as is often the case. Clearly this is very dangerous yet most will subject themselves vily nily to this procedure in the misguided faith in the early detection myth... Any advantage one gets from early detection has now become a liability as cancer growth rate has accelerated often to the point that the patient has now become an emergency case.

Which also references this article:

Even though cancer is considered abnormal and rapid growth of cells, the entire mass of a cancer is normally rather slow growing -- because it is "encased." It grows inside a wall, or shell. The body is trying to protect itself from the cancer -- because cancer would otherwise spread throughout the body. So, the body tries to protect itself by building a wall around the cancer to keep any of its cells from "leaking out." (Actually, some cancers are very slow-growing [breast and prostate] while others are very fast [liver cancer].)

However these claims seem to be controversial, as doctors still doing biopsies routinely.

Answer 1

It is possible for a biopsy to spread cancer, however this is rare and it would not be accurate to describe a biopsy as "very dangerous".

PubMed articles:

Rare potential complications of thyroid fine needle biopsy

needle track seeding (or tumor dissemination) is very rare in vivo. Tumor cells released into the surrounding tissues or circulation after FNB are probably destroyed by the host immune response or other mechanisms before giving rise to clinically apparent metastases.

Fine-Needle Aspiration Biopsy of Hepatocellular Carcinoma and Related Hepatocellular Nodular Lesions in Cirrhosis: Controversies, Challenges, and Expectations

The most contentious complication cited by detractors of the technique is the risk of needle-tract seeding turning a potentially operable case of HCC to a metastatic state. Risk of implantation metastases after biopsy for malignancy in general is considered rare (0.003–0.009%);

Answer 2

I think this link perfectly addresses cancer metastatis

Metastatic cancer is cancer that has spread from the place where it first started to another place in the body. A tumor formed by metastatic cancer cells is called a metastatic tumor or a metastasis. The process by which cancer cells spread to other parts of the body is also called metastasis.

And

Not all cancer cells, by themselves, have the ability to metastasize. In addition, the noncancerous cells at the original location may be able to block cancer cell metastasis.

But basically some cells can relocate. Almost all cancer types can spread.

The biopsy is used because it is a way to extract the cells from the body to study them. There is not enough known about all cancers that research is needed.

But the biopsy may cause cells to enter the bloodstream and allow them to form a Metastatic tumor elsewhere in the body. But sometimes the value of the biopsy results are worth the risk when it will provide a proper treatment program.

I would also note that biopsy is just one of many diagnostic procedures that can be performed.