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Test Code PIK3T PIK3CA Mutation Analysis, Tumor


Necessary Information


A pathology report (final or preliminary), at minimum containing the following information, must accompany specimen for testing to be performed:

1. Patient name

2. Block number-must be on all blocks, slides, and paperwork (can be handwritten on the paperwork)

3. Tissue collection date

4. Source of the tissue



Specimen Required


This assay requires at least 20% tumor nuclei.

The amount of tissue needed is dependent on a variety of preanalytical factors (eg, cellularity, ischemic time, fixation).

The FFPE input required is equivalent to a 4 to 5 micron slide thickness with a total tumor surface area of 100 mm(2). This can be created by combining material from multiple slides from one tissue block.

 

Preferred:

Specimen Type: Tissue block

Collection Instructions: Submit a formalin-fixed, paraffin-embedded tissue block.

 

Acceptable:

Specimen Type: Tissue slide

Slides: 1 stained and 10 unstained

Collection Instructions: Submit 1 slide stained with hematoxylin and eosin and 10 unstained, nonbaked slides with 5-micron thick sections of the tumor tissue.


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).

Testing Algorithm

When this test is ordered, slide review will always be performed at an additional charge.

Method Name

Polymerase Chain Reaction (PCR)

Reporting Name

PIK3CA Mutation Analysis, Tumor

Specimen Type

Varies

Specimen Minimum Volume

See Specimen Required

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)
  Refrigerated 

Reject Due To

Specimens that have been decalcified (all methods)
 Specimens that have not been formalin-fixed, paraffin-embedded		 Reject

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 (p110alpha) 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 DNA extracted from tumors 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.

Day(s) Performed

Monday through Friday

Report Available

8 to 12 days

Specimen Retention Time

Unused portions of blocks will be returned. Unused slides: Indefinitely

Performing 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
PIK3T PIK3CA Mutation Analysis, Tumor 60034-6

 

Result ID Test Result Name Result LOINC Value
616654 Result Summary 50397-9
616655 Result 82939-0
616656 Interpretation 69047-9
616657 Additional Information 48767-8
616658 Specimen 31208-2
616659 Source 31208-2
616660 Tissue ID 80398-1
616661 Released By 18771-6

Forms

If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.