EGFR mutation testing is a laboratory test that looks for specific DNA changes in the EGFR gene. It is most commonly used in certain solid tumors, especially non-small cell lung cancer. The goal is to identify tumor features that may affect diagnosis and treatment planning. Testing can be done on tumor tissue or sometimes on a blood sample.

ALK FISH is a laboratory test that looks for changes in the ALK gene in tumor cells. It uses fluorescent markers to detect ALK gene rearrangements under a microscope. It is most commonly used in certain lung cancers and some rare tumors and lymphomas. Results can help clinicians match a cancer to targeted treatments when appropriate.

HER2 FISH is a laboratory test that measures the HER2 gene in cancer cells. It uses fluorescent probes to check whether the HER2 gene is amplified (present in extra copies). It is most commonly used in breast cancer and some gastrointestinal cancers to guide treatment planning. It is performed on tumor tissue (or sometimes cell samples) reviewed by a pathology laboratory.

HER2 IHC is a laboratory test that measures HER2 protein on the surface of tumor cells. It uses immunohistochemistry (IHC), a staining method performed on a tissue sample under a microscope. HER2 IHC is commonly used in cancers where HER2 status can affect diagnosis and treatment planning. It is most widely discussed in breast cancer, and it is also used in some other solid tumors.

PD-L1 IHC is a lab test that looks for the PD-L1 protein in a cancer tissue sample. It uses immunohistochemistry (IHC), a staining method that makes certain proteins visible under a microscope. It is commonly used in oncology to help guide immunotherapy decisions and to describe tumor biology.

MMR IHC is a lab test that checks whether a tumor has working mismatch repair (MMR) proteins. It is performed on tumor tissue, most often from a biopsy or surgery specimen. MMR IHC is commonly used in cancers like colorectal and endometrial cancer to guide further testing and treatment planning. It can also help identify people who may benefit from genetic evaluation for inherited cancer risk.

MSI testing is a laboratory test that looks for a pattern of DNA changes called microsatellite instability in a tumor. It helps clinicians understand how a cancer is behaving at the molecular level. MSI testing is commonly used in colorectal and endometrial cancers, and it may be used in other tumor types. Results can inform diagnosis, inherited cancer risk evaluation, and treatment planning.

HRD testing looks for signs that a tumor has trouble repairing certain types of DNA damage. HRD stands for **homologous recombination deficiency**, a problem in a key DNA repair pathway. It is most commonly used in **solid tumors**, especially ovarian cancer, and sometimes breast, prostate, and pancreatic cancers. The goal is to help clinicians understand tumor biology and support treatment planning.

BRCA testing is a genetic test that looks for changes (variants) in the BRCA1 and BRCA2 genes. These genes help repair damaged DNA, and certain harmful variants can increase cancer risk. BRCA testing is commonly used in breast, ovarian, prostate, and pancreatic cancer care. It can be done using blood, saliva, or tumor tissue depending on the clinical question.

Somatic testing is laboratory testing that looks for genetic changes in cancer cells. These changes are acquired over a person’s lifetime and are not usually inherited. Somatic testing is commonly used after a cancer diagnosis to help characterize the tumor. Results may support diagnosis, prognosis, and treatment planning in many oncology settings.