Advancements in Cancer Detection: The Role of Liquid Biopsies

Understanding Traditional Biopsies

A biopsy is a medical procedure where physicians extract a small sample of cells or tissues to diagnose cancer and assess its stage. Various invasive techniques exist for conducting biopsies, but their use is limited since they cannot be performed frequently on the same patient. Therefore, enhancing cancer detection methods is essential.

Liquid Biopsy: A New Diagnostic Approach

A recent review published in Science Magazine explores the potential of liquid biopsies, which utilize blood samples to identify cancer. Researchers aimed to determine the effectiveness of blood tests as a detection method for cancer.

Methodology and Findings

The study leveraged known DNA mutations that drive tumor cell division, which eventually release mutated DNA into the bloodstream upon cell death. However, detecting these small amounts of mutated DNA poses a challenge. To improve detection rates, the researchers combined the identification of mutated DNA with other genes and proteins. They developed a system called CancerSEEK, incorporating eight additional biomarkers associated with various cancers, significantly enhancing detection rates and enabling accurate predictions of cancer tissue types.

Effectiveness of Liquid Biopsies

Blood samples were collected from over 1,000 patients diagnosed with eight different tumor types, including ovarian, liver, stomach, pancreas, esophageal, colorectal, lung, and breast cancers. The liquid biopsy demonstrated a detection rate ranging from 33% to 98%, depending on the tumor type. Notably, the detection rate for hard-to-detect cancers was 69% or higher, with less than 1% of healthy controls returning false positives. Additionally, the test could narrow down the tissue origin of cancer to two possibilities in over 80% of cases. The cost for each liquid biopsy sample is approximately $500, making it relatively affordable.

Limitations of Liquid Biopsies

Despite their advantages, liquid biopsies have limitations. The same proteins used as cancer biomarkers may also be present in individuals with inflammatory diseases, potentially increasing the false positive rate in the general population. Furthermore, smaller tumors release less mutated DNA into the bloodstream, leading to lower detection rates; specifically, only 43% of stage one cancers were identified using this method.

Future Implications

The research team behind this technology believes that liquid biopsies are ready for clinical use as a screening tool. They assert that while no diagnostic method is perfect, the benefits of liquid biopsies can aid in early detection and subsequent imaging procedures for patients who test positive. This innovative approach could facilitate earlier cancer screening in clinical settings.

Conclusion

The development of liquid biopsies represents a promising advancement in cancer detection. By integrating multiple biomarkers, this method provides a less invasive alternative to traditional biopsies and may become a vital tool in the early diagnosis of various cancers.

Written by Ingrid Qemo, BSc

Reference: Kaiser, J. (Jan, 18, 2018). “Liquid biopsy” promises early detection for cancer. Science Magazine. doi:10.1126/science.aat0349.