The use of cytology specimens for molecular analysis of solid tumors is a proven means to establish a patient’s molecular diagnosis — a vitally important aspect of choosing the most effective treatment for a patient’s specific cancer. When the amount of available tissue specimen is inadequate for molecular testing, use of cytology specimens presents a compelling testing approach.
Cytology specimen testing, however, is considerably underutilized. In fact, recent Mayo Clinic Laboratories research into the use of cytology testing showed that cytology samples comprise just 18% of specimens submitted for comprehensive genomic profiling to detect somatic alterations in solid tumors.1 Among the reasons for this underuse are lack of validation of molecular tests for cytology samples and fear of sample inaccessibility following testing.
29%
of comprehensive solid tumor cases ordered by Mayo Clinic physicians used cytology
2%
of comprehensive solid tumor cases ordered by external clients used cytology
Transforming cancer testing
To help providers overcome any hesitancy toward using cytology samples for molecular testing and minimize instances of tumor inadequacy due to insufficient tissue samples, we’ve produced an educational resource backed by Mayo Clinic cytology testing experts.
Our digital guide is a must-read for providers looking to gain precision answers and personalize treatment for their patients.
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Ensuring Desired Molecular Testing Results for Cancer Patients, Cytology Specimen Utilization: A Proven Approach to Genetic Sequencing
“The availability of robustly validated NGS testing on cytology specimens ensures that more oncology patients get the successful NGS testing that is so critically important for guiding their care.”
An advantageous alternative
The use of cytology samples for molecular testing has several advantages. The cellular integrity of smear specimens, which are typically prepared with alcohol-based fixatives, is often superior to FFPE tissue specimens. And unlike FFPE tissue block preparations, which entail cutting the block and the embedded cells within, direct smear cytology slides are prepared by applying whole cells directly onto the slide. This preserves the structure of the cells’ genetic contents.
More importantly, especially for lung and liver tumors, cytology specimens are sometimes the only type of specimen available for testing. In other cases, biopsied FFPE tissue samples are entirely or almost entirely needed for histopathological or immunohistochemistry testing, leaving insufficient material for molecular investigations.
We recognize that when cytology specimens are submitted alongside FFPE tissue samples, a high molecular testing success rate can be attained. We have validated nearly all our NGS oncology panels to accept cytology specimens, including smears and cell blocks.
Highlights
Offering increased sensitivity and improved accuracy, MayoComplete next-generation testing ensures health care providers understand the distinctive genetic features of their patients’ cancer to make informed decisions to guide their care.
In this month's "Hot Topic," Kevin Halling, M.D., Ph.D., discusses new next generation sequencing testing for various tumor types and the rationale for the enhancements that were made; reviews gene additions that are now available in each of the panels; and briefly speaks about the work that was done to validate cytology specimens for use in the subpanels.