Liquid Biopsy vs Surgical Biopsy (FFPE)

When a doctor suspects someone may have cancer, a surgery is usually performed to take a sample (tumor) for further testing. Commonly also called a biopsy to get a tumor block. The tumor is then stored or preserved in a special material called FFPE.

What is FFPE?

Formalin-Fixed Paraffin-Embedded (FFPE) blocks, also known tissue blocks, until very recently, has been the most common method of preserving the tumor of a cancer patient for further testing. Tests on the tumor conducted on FFPE blocks can greatly help to decide the treatment for a patient. FFPE also allow for easy transportation and preservation of the sample.

What are the downsides of FFPE?

FFPE blocks cannot always be obtained due to a variety of reasons:

• The tumor is in a location that’s difficult or impossible to safely biopsy (for example brain tumors)
• The patient’s health does not allow for a biopsy
• The biopsy has already been done, but yielded very little or no tumor
• Tumor has been exhausted after multiple tests have been performed

Generally, the older the FFPE blocks are, the less reliable the testing may be clinically.

What can one do when tumor block biopsy is not an option?

When FFPE is unavaliable, liquid biopsy, also called circulating tumor DNA or CT DNA*, is increasingly used as an emerging option. Liquid biopsy is non-invasive alternative – simply a blood draw. After the blood is drawn, the lab extracts cancer tumor DNA floating in the bloodstream to perform testing.

When should one opt for Liquid Biopsy?

Liquid biopsies are typically used in situations where FFPE is not available. However, there are differences in liquid biopsy testing vs FFPE testing. As an emerging technology, liquid biopsies, cannot at this stage replace FFPE testing but has been shown effective as an alternative in many cases.

What can Liquid Biopsy tell you?

By taking your blood, you can answer several questions such as

• Is cancer present?
• Which genes are positive for treatment options?
• What treatment might work?
• Is immunotherapy an option?
• Is there any cancer cells left?

How is Liquid Biopsy tested?

Liquid biopsy analyses ones blood sample to extract information as cancer cells would be circulating in the blood. Traces of the cancer’s DNA in the blood can give clues about which treatments are most likely to work for that patient. Testing is often carried on next-generation sequencing (NGS), a newer more advanced technology than RT-PCR or IHC, which is usually used for FFPE. However, NGS testing has also become popular for FFPE.

What tests can be performed on Liquid Biopsy?

At Positive Bioscience, we are able to perform all PositiveSelect tests using just blood. These tests include:

• PositiveSelect Lite
• PositiveSelect Match
• PositiveSelect Plus
• PositiveSelect Ultimate
• PositiveSelect Lung
• PositiveSelect Colorectal
• PositiveSelect Immunotherapy

What are the pros and cons of Liquid Biopsy vs FFPE?

*

Note: circulating tumor DNA and circulating tumor cells are different tests.

Photo Credits:

https://www.genengnews.com/wp-content/uploads/2018/08/biopsies3_CVJ_small_white1431669208-1.png &

https://www.asianscientist.com/2017/08/print/medicines-new-stethoscope/