Molecular markers: Implications for cytopathology and specimen collection

Abstract

Cytologic specimens obtained through minimally invasive biopsy techniques are increasingly being used as principle diagnostic specimens for tumors arising in multiple sites. The number and scope of ancillary tests performed on these specimens have grown substantially over the past decade, including many molecular markers that not only can aid in formulating accurate and specific diagnoses but also can provide prognostic or therapeutic information to help direct clinical decisions. Thus, the cytopathologist needs to ensure that adequate material is collected and appropriately processed for the study of relevant molecular markers, many of which are specific to tumor site. This brief review covers considerations for effective cytologic specimen collection and processing to ensure diagnostic and testing success. In addition, a general overview is provided of molecular markers pertinent to tumors from a variety of sites. The recognition of these established and emerging molecular markers by cytopathologists is an important step toward realizing the promise of personalized medicine. Cancer (Cancer Cytopathol) 2015;123:454-60.

Utilization of ancillary studies in the cytologic diagnosis of respiratory lesions: The papanicolaou society of cytopathology consensus recommendations for respiratory cytology

“…72,73 In general, when tissue is limited, EGFR testing is prioritized and performed before ALK . 62,72 Additional markers that may be tested in pulmonary adenocarcinomas include KRAS, ROS1, BRAF, RET , MET, neurotrophic tyrosine kinase receptor type 1 ( NTRK1 ) and v-erb-b2 erythroblastic leukemia viral oncogene homolog2 ( ERBB2 ).…”

“…62,72 Additional markers that may be tested in pulmonary adenocarcinomas include KRAS, ROS1, BRAF, RET , MET, neurotrophic tyrosine kinase receptor type 1 ( NTRK1 ) and v-erb-b2 erythroblastic leukemia viral oncogene homolog2 ( ERBB2 ). 73,74 While no recommendations for prioritization of these markers have yet been published, some authorities recommend early performance of KRAS analysis. KRAS mutations appear to exclude mutations in EGFR and EML4-ALK and the KRAS gene product is present in the control pathway before EGFR and EML4-ALK , thus negating the impact of these latter two genes.…”

“…75 Other potential targets are phosphatase and tensin homolog ( PTEN ), platelet-derived growth factor receptor alpha ( PDGFRA ) and discoidin domain-containing receptor 2 ( DDR2 ). 73,75 …”

“…3,65–69 While FFPE material is one of the most common sources of material for molecular analysis in many laboratories, 67, 72 recent studies have shown that material obtained from air-dried and alcohol-fixed cytologic smears can be reliably used. 61,62,73,74 Sample adequacy for analysis should be confirmed by a pathologist. While specimens with 20% or greater cancer cells are prefered, 62 many laboratories have reported successful results using significantly lower concentration of cancer cells, provided the sample meets the analytic sensitivity of the platform used and with appropriate validation studies.…”

Do More With Less: Tips and Techniques for Maximizing Small Biopsy and Cytology Specimens for Molecular and Ancillary Testing: The University of Colorado Experience

“…Driven in large part by increased utilization of minimally invasive tissue sampling techniques—such as small-gauge needle biopsies and fine-needle aspirates (FNAs) obtained in an interventional radiology setting for deep-seated lesions, endobronchial ultrasound evaluation of thoracic lymph nodes, fine-needle aspiration of superficial lesions, and a myriad of other approaches—pathologists increasingly must not only issue diagnoses on tissues of smaller total volume, but also serve in a tissue triage role to ensure adequate distribution for ancillary testing. 6,7 …”