The Tissue Biopsy
A biopsy is the removal of a small piece of tissue or cells. This is then analyzed under a microscope to look for abnormalities or mutations. A biopsy is one of the first steps a doctor will take when a patient exhibits symptoms of cancer or another serious disease. For most types of cancers, a biopsy is the only definitive way to differentiate cancerous cells from noncancerous ones. This method can also aid in determining what type of cancer is present (if any) and how advanced the cancer is. There are 3 common types of biopsies:
- A sample of the tissue is removed, known as an incisional biopsy
- An entire lump or mass is removed, known as an excisional biopsy
- A sample of fluid or tissue is removed via needle, known as a needle biopsy
Although tissue biopsies are necessary to diagnose a serious illness, they can be painful, costly, and invasive. Furthermore, they are an impractical way to track tumors as they change over time. Researchers have been looking into ways to make biopsies less invasive and easier to obtain. Hence, the liquid biopsy.
The Liquid Biopsy
Scientists have discovered tumors shed molecules into bodily fluids. A liquid biopsy takes a sample of a bodily fluid, such as blood, urine, spinal fluid or saliva, to analyze cancer cells or molecules that are circulating within the fluid. It can help detect certain cancers in the early stages and monitor its progression. There are several different types of liquid biopsies. They can be used to analyze different kinds of tumor materials, such as RNA, proteins, DNA, exosomes, and the entire cancer cell. Liquid biopsies are easier to take. Therefore, doctors are able to track molecular changes more easily. This is important for patients that are at high risk of the disease returning or worsening.
Risks Involved with a Liquid Biopsy
There are some reservations about relying solely on liquid biopsies to detect cancerous cells. Tests can sometimes produce false-positives. Also, there are concerns that the biopsy will detect early stage tumors that will not actually harm the body. This discovery may result in overtreatment. The National Cancer Institute is attempting to develop a liquid biopsy technology that can differentiate between cancerous and benign conditions, and identify fast vs. slow growing cancers.
Another concern is the detection of biomarkers. Biomarkers allow scientists to track the disease by DNA mutations. Some biomarkers only exist for advanced stages of cancer, and not in the early detection stages. Furthermore, many cancers don’t have any biomarkers at all. This complexity makes it more difficult to identify certain types of cancer by just a liquid biopsy.
Hope for the Future
In conclusion, scientists are weighing the pros and cons of using liquid biopsies over traditional tissue biopsies. Ultimately, they need to determine whether these tests can improve patient survival. The convenience and cost factors are in favor of liquid biopsies, but this means nothing if they are not as efficient at detecting and treating cancer. Universities all over the world are conducting studies to improve liquid biopsies and how we interpret the results.
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