Testing for Tumor Mutations: Liquid Biopsy Versus Traditional Biopsy

Liquid biopsies, virtually unknown even a year or two ago, are becoming common tools in precision diagnostics for cancer. Here, I will try to explain some of the more important differences between liquid and “traditional” tumor biopsies.

Biopsies of solid tumors (e.g., lung, breast, or brain tumors) involve surgically removing a small part of a tumor and sending it to pathology lab. In the last few years, doctors have also started to send some tumor samples to special service labs that analyze tumor DNA for the presence of cancer-related mutations.

By definition, regular biopsies can be intrusive and are sometimes associated with side effects, such as bleeding or infection. However, they provide some really essential information; i.e., the histology and grade of the tumor and other tumor characteristics necessary to determine the best choice of treatment. For lung cancer, for example, a biopsy determines the type of tumor—adenocarcinoma, squamous cancer, small-cell lung cancer, or another, less common type. For breast cancer, a routine test will determine if the tumor expresses estrogen, progesterone receptors, and a protein called HER2. These tests are critically important in guiding treatment choices. If mutational analysis of cancer-related genes is also performed (which doesn’t always happen, unfortunately), it may guide treatment with targeted drugs. Continue reading…

RNA Diagnostic Test Improves Diagnosis of Lung Cancer

The first step towards choosing the best lung cancer treatment is to figure out what specific kind of lung cancer a patient has. Usually, doctors can determine cancer type by surgically removing part of a tumor and examining the appearance of tumor cells under a microscope. But sometimes tumor samples are damaged and difficult to analyze visually, so a second method would be useful to help confirm a diagnosis. Researchers have now developed a new test that can determine which genes are turned on or off in tumor cells, allowing them to distinguish between the most common types of lung cancer (adenocarcinoma, carcinoid, small cell carcinoma, squamous cell carcinoma). Samples of tumors are already routinely collected, and, in an experiment, examining them and analyzing their genetics was found to be a viable predictor of a tumor’s microscopic appearance. Researchers hope that their test will bring more accurate diagnoses to doctors and patients, which in turn could lead to better treatment recommendations and better outcomes.