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HelpTest Code PIK3B Cell-Free DNA PIK3CA Test, Blood
Shipping Instructions
1. Samples should be transported at ambient temperature or refrigerated (4° C)
2. Samples are viable for 7 days in the Streck Black/Tan Top Tube Kit
Specimen Required
Supplies: Streck Black/Tan Top Tube Kit (T715)
Specimen Volume: Two, 10-mL Streck cell-free DNA (cfDNA) blood collection tubes
Additional Information:
1. Only blood collected in Streck cfDNA tubes will be accepted for analysis.
2. Whole blood will be processed to produce platelet-poor plasma before cfDNA isolation.
Useful For
Identification of hormone receptor positive and human epidermal growth factor receptor 2 negative (HR+/HER2-) advanced breast cancer tumors that may be eligible for treatment with targeted kinase inhibitor therapy (eg, alpelisib).
Method Name
Polymerase Chain Reaction (PCR)
Reporting Name
cfDNA PIK3CA Test, BloodSpecimen Type
Whole bloodSpecimen Minimum Volume
One 10 mL Streck cell-free DNA tube
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole blood | Ambient (preferred) | 7 days | Streck Black/Tan top |
| Refrigerated | 7 days | Streck Black/Tan top |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Clinical Information
More than 70% of breast cancers are hormone receptor (HR) positive and human epidermal growth factor receptor 2 (HER2) negative (HR+/HER2-). Approximately 40% of patients with HR+/HER2- advanced breast cancer have activating mutations in the gene PIK3CA, inducing hyperactivation of the alpha isoform (p110 alpha) of phosphatidylinositol 3-kinase, a key upstream component of the PI3K pathway. Mutations in PIK3CA are associated with tumor growth, resistance to endocrine therapy, and a poor overall prognosis.
Patients with HR+/HER2- advanced breast cancer identified to have a PIK3CA mutation may be eligible for treatment with targeted kinase inhibitor therapy (eg, alpelisib).
This test uses circulating tumor DNA extracted from blood to evaluate for the presence of 10 clinically actionable PIK3CA mutations:
E542K (c.1624G>A)
E542K (c.1633G>A)
E545D (c.1635G>T)
E545G (c.1634A>G)
E545A (c.1634A>C)
H1047Y (c.3139C>T)
C420R (c.1285C>T)
Q546E (c.1636C>G)
H1047L (c.3140A>T)
H1047R (c.3140A>G)
Reference Values
An interpretive report will be provided
Interpretation
The interpretation of molecular biomarker results includes an overview of the results and the associated diagnostic, prognostic, and therapeutic implications.
Cautions
A negative (wildtype) result does not rule out the presence of a mutation that may be present but below the limits of detection of this assay. It also does not rule out the presence of other types of alterations in the PIK3CA gene outside those that the assay was designed to detect.
This test is not designed to differentiate between somatic and germline alterations. Additional testing may be necessary to clarify the significance of results if there is a potential hereditary risk.
Not all tumors that have PIK3CA mutations will respond to targeted therapies.
Rare genetic alterations exist that could lead to false-negative or false-positive results.
This test has not been clinically validated for use as a tool to monitor response to therapy or for early detection of tumors.
Test results should be interpreted in context of clinical findings, tumor sampling, and other laboratory data. If results obtained do not match other clinical or laboratory findings, please contact the laboratory for possible interpretation. Misinterpretation of results may occur if the information provided is inaccurate or incomplete.
Method Description
A polymerase-chain reaction (PCR)-based assay employing real-time PCR and allele-specific PCR technologies is used to test for 10 mutations within PIK3CA (C420R, E542K, E545A, E545D, E545G, E545K, Q546E, H1047L, H1047R, and H1047Y).(Package insert: therascreen PIK3CA RGQ PCR Kit. Qiagen; 05/2019)
Day(s) Performed
Monday through Friday
Report Available
5 to 10 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
81309
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PIK3B | cfDNA PIK3CA Test, Blood | 60034-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 616647 | Result Summary | 50397-9 |
| 616648 | Result | 82939-0 |
| 616649 | Interpretation | 69047-9 |
| 616650 | Additional Info | 48767-8 |
| 616651 | Specimen | 31208-2 |
| 616652 | Source | 31208-2 |
| 616653 | Released By | 18771-6 |