As I often like to joke with my co-workers, there’s a lot of “alphabet soup” in oncology. From the many professional staff I work with (RN, LCSW, MA, MD, PhD, RD) to the endless combination of letters associated with patient diagnoses, this APRN, AOCNP can get lost swimming in the soup!
We are now in the age of biomarkers, which are “substances found in the blood, other body fluids, or tissues that signal the presence or absence of cancer".¹ Biomarkers help in determining risk for, diagnosis of, and overall prognosis of cancer. I don’t know if you’ve been keeping up, but we now have a lot of acronyms or short-letter names for these various biomarkers in oncology.
So I thought it might be helpful to break down some of the letter jargon to make a patient’s case easier to navigate. A full discussion of all cancer biomarkers is beyond this simple blog. So let’s review the more commonly used markers in three solid tumor categories:
EGFR (epidermal growth factor receptor): Patients with EGFR mutation/overexpression are more likely to benefit from Tyrosine Kinase Inhibitors (TKI agents) such as Tarceva (erlotinib), Iressa (gefitinib).
KRAS (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog): Patients with a KRAS mutation will likely have resistance to TKI therapy.
ELM4-ALK: Fusion of ELM4 gene with ALK (anaplastic lymphoma kinase) gene, both of which are located on chromosome 2p but are normally separated.² Patients with this gene mutation are likely to be responsive to agents that target the ALK fusion protein such as Xalkori (crizotinib).
ER/PR(estrogen receptor/progesterone receptor): Patients with positivity to one or both receptors may benefit from endocrine therapy for treatment of their cancer or prevention of future recurrence with drugs such as an estrogen receptor antagonist Novaldex (tamoxifen) or aromatase Inhibitors Arimidex (anastrozole), Femara (letrozole), and Aromasin (exemestane).
HER2 status (Human Epidermal Growth Factor Receptor 2): Patients with overexpression (i.e., HER2-positive) have increased rate of metastasis, decreased time to recurrence, and a decrease in overall survival.3 Patients are more likely to respond to therapies targeting HER2 overexpression such as Herceptin (trastuzumab), Tykerb (lapatinib), Perjeta (pertuzumab).
Ki-67 protein (a nuclear antigen expressed throughout the cell cycle): Patients demonstrating a high Ki-67 expression is a sign of poor prognosis but patients also have a better chance of initial response to chemotherapy.3
p53 (tumor protein 53 (tumor suppressor protein): Some studies show patients with a p53 mutation have a worse outcome and shorter survival time.4
MSI: microsatellite instability (accumulation of abnormalities in short sequences of DNA bases that are repeated dozens to hundreds of times within the genome). Some studies have shown that patients with high MSI have an increased five-year survival rate while others show an association between the presence of MSI and resistance to chemotherapy.4
EGFR (epidermal growth factor receptor): Patients with EGFR mutation/overexpression are more likely to benefit from EGFR inhibitor therapy such as Erbitux (cetuximab) or Vectibix (panitumumab).
KRAS (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog): Patients with a KRAS mutation will likely not respond to agents targeting EGFR.
Hopefully this brief summary will help you in clinical practice. What other commonly used biomarker acronyms can you add to the list?
National Comprehensive Cancer Network (2013). Biomarkers and targeted therapy. http://www.nccn.com/index.php?option=com_content&view=article&id=927:biomarkers-and-targeted-therapy&catid=56 Accessed June 25, 2013.
Kreamer, K., Eaby-Sandy, B., Sherry, V., & Stonehouse-Lee, S. (2011). Biomarkers in non-small cell lung cancer: opportunity and challenge. Journal of the Advanced Practitioner in Oncology, 2(3), 163-175.
Beikman, S., Gordon, P.,Ferrari, S., Siegel, M., Zalewski, M., Rosenzweig, M. (2013). Understanding the Implications of the breast cancer pathology report: a case study. Journal of the Advanced Practitioner in Oncology, 4(3), 176-181.
Sepulveda, A. (2007). The importance of microsatellite instability in colonic neoplasms. http://www.medscape.org/viewarticle/571610 Accessed June 26, 2013.