VUS means **Variant of Uncertain Significance**. It is a **genetic test result** showing a DNA change that scientists cannot currently label as harmful or harmless. VUS is most commonly discussed in **hereditary cancer testing** (germline testing) and **tumor genetic testing** (somatic testing). It helps describe uncertainty in genomics rather than confirming or ruling out cancer by itself.
A Variant of unknown significance is a genetic test finding where a DNA change is detected, but its health meaning is not clear. It is commonly reported in germline (inherited) and tumor (somatic) genetic testing used in cancer care. It means the lab cannot confidently label the variant as harmful (pathogenic) or harmless (benign) right now. The classification can change over time as new scientific evidence becomes available.
A Germline mutation is a change in DNA that is inherited and present from birth. It is found in virtually every cell of the body because it starts in an egg or sperm cell. In oncology, it is commonly discussed in hereditary cancer risk, genetic testing, and family counseling. It can influence screening plans and, in some cases, treatment options.
Somatic mutation means a DNA change that happens after conception in a body cell. It is not usually inherited from a parent and is not typically passed to children. Somatic mutation is commonly discussed in cancer because tumors often contain these DNA changes. Clinicians use somatic mutation results to help classify cancers and consider treatment options.
Triple-negative is a pathology and oncology term that describes a tumor that tests negative for three common biomarkers. It is most commonly used in breast cancer to mean estrogen receptor (ER)-negative, progesterone receptor (PR)-negative, and HER2-negative. The label helps clinicians describe tumor biology and choose treatments that are more likely to work. It is a classification based on lab testing, not a treatment by itself.
Hormone receptor positive means a tumor’s cells have receptors that can bind certain hormones. It is most commonly used to describe breast cancers that are estrogen receptor (ER) and/or progesterone receptor (PR) positive. The term helps clinicians predict whether hormone-blocking treatments are likely to work. It is determined by laboratory testing on tumor tissue.
HER2 overexpression means a tumor makes unusually high amounts of the HER2 protein on the surface of its cancer cells. It is a biomarker finding reported by pathology labs, not a symptom you can feel. It is most commonly discussed in breast cancer and some gastrointestinal cancers, and it can influence treatment planning. It is usually identified on tumor tissue from a biopsy or surgery.
PD-L1 expression describes how much of the PD-L1 protein is present on tumor cells and/or nearby immune cells. It is usually measured in a pathology lab using a sample from a biopsy or surgery. Clinicians most often use PD-L1 expression to help guide immunotherapy decisions in certain cancers. It is a biomarker test, meaning it provides information about the tumor’s biology rather than treating the cancer by itself.
TMB stands for **tumor mutational burden**. It is a measurement of how many DNA changes (mutations) are found in a tumor’s genetic material. TMB is commonly reported from **next-generation sequencing (NGS)** tests on tumor tissue or sometimes blood. Clinicians may use TMB as one piece of information when considering **immunotherapy** and clinical trial options.
Tumor mutational burden is a measure of how many genetic changes (mutations) are found in a cancer’s DNA. It is reported as the number of mutations per amount of DNA tested, using standardized lab methods. It is most commonly used in molecular pathology to help interpret biomarker testing results. It can support treatment planning, especially when immunotherapy is being considered.