Could liquid biopsies change the way we detect and monitor cancer?

Liquid biopsies analyze tumor-derived material present in body fluids—most commonly blood—to gather critical information about the cancer.

It is different from traditional tissue biopsies, which require surgery or needle extraction from a tumor site.

It is much simpler being just a blood draw, it avoids the discomfort and risks associated with tissue biopsy procedures, which might require imaging guidance or surgery.

It can pick up tiny amounts of circulating tumor DNA (ctDNA) or circulating tumor cells (CTCs) released by cancer. This technology is proven to be useful in surveillance post treatment predicting recurrence before it is apparent on clinical examination or PET scans.

It also detects cfDNA (cell free DNA) in the bloodstream, which includes fragments of DNA shed from normal cells and tumor cells. Thus, it can detect inherent aberrations like BRCA1/2, TP53 in an individuals normal cells which informs us of the increase risk of cancer development

There is another technology being developed which instead of directly identifying cancer cells or cancer DNA in the blood stream evaluates and records the changes occurring in our immune system or White blood Cells(WBC). Cancer is our body’s own cell which goes wrong. Our body’s immune system detects and eliminates these deranged or bad cells. Tumor is formed when these cells find their way pass the immune system. It is these concept that is identifying changes in immune system or our WBC which is being used to detect cancerous changes in our body.

The present utility of liquid biopsy
Surveillance and recurrence prediction
Providing DNA / RNA for precison oncology i.e. studying the aberrations in genomic pathways causing the cancer and identifying pharmaceutical i.e. drug or neutraceutical i.e. dietary supplement / traditional medicine which can target the aberration and correct it.

Screening or early detection: This is an important aspect which needs proper explanation. At present we do not recommend liquid biopsy to be used as mass screening method. But it can be used in special situations such as there is mass in the uterus which needs an invasive biopsy to identify whether it is just a fibroid or malignant mass; liquid biopsy can help with just a blood test and then a proper procedure can be planned accordingly. A white or red colored plaque in mouth for a young man who has been a smoker or tobacco chewer, liquid biopsy (blood sample) can determine whether it needs to be removed and treated as cancer (Tumor cells or tumor DNA if found in blood stream confirms it as cancer) or can be kept under observation. Patient having lesions in the bone/lung/liver where biopsy is difficult and dangerous liquid biopsy definitely is a safe and good option.

In situations, when patient is in denial or will not go for biopsy(he/she believes that by undergoing biopsy the cancer will spread) then liquid biopsy (blood sample) can solve this problem and prevent a patient to progress to advanced stage of cancer.

Note: Liquid Biopsy is not preferred for brain tumors as there exists a blood brain barrier which prevents brain cells or ther components to come in blood stream.

Dr Mandeep Singh Malhotra, Senior oncologist, Art of healing cancer