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UGT1A1 Irinotecan Toxicity

CPT 81350
Synonyms
  • Camptosar┬«
  • Irinotecan

Test Details

Cancer Type

Colorectal cancer (CRC)

Technology Used

Molecular

Turnaround Time

5 - 7 days

Use

Irinotecan (Camptosar®) is used, or under evaluation, in a broad spectrum of solid tumors, and is often prescribed for treating patients with metastatic cancer of the colon or rectum, especially when 5-fluorouracil treatment has not been entirely successful. Severe toxicity (eg, grade 4 neutropenia) is commonly observed in cancer patients receiving irinotecan who carry the UGT1A1*28 allele, also called TA. This test result will provide valuable information to physicians prior to initiating or modifying treatment or supplementing treatment with additional drugs.

UGT1A1 variants have also been reported in patients with disorders of bilirubin metabolism, such as Crigler-Najjar Types I and II, as well as Gilbert syndrome. Between 80% to 100% of Caucasian patients with Gilbert syndrome are reported to have either one or two copies of UGT1A1*28. G71R (*6), a UGT1A1 variant reported in Asian patients with Gilbert syndrome, is not detected by this assay.

Limitations

The current test will only test the TATA box polymorphism of the UGT1A1 gene. The other polymorphisms of this gene will not be detected.

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA).

Methodology

Polymerase chain reaction (PCR); capillary electrophoresis

Specimen Requirements

Information on collection, storage, and volume

Specimen

Whole blood or LabCorp buccal swab kit (buccal swab collection kit contains instructions for use of a buccal swab)

Volume

5 mL whole blood or LabCorp buccal swab kit

Minimum Volume

3 mL whole blood or two buccal swabs

Container

Lavender-top (EDTA) tube, yellow-top (ACD) tube, or LabCorp buccal swab kit

Storage Instructions

Maintain whole blood specimen at room temperature for 7 days or refrigerated for 1 month, or frozen for 2 years. Maintain buccal swabs at room temperature for 6 months.

Causes for Rejection

Hemolysis; quantity not sufficient for analysis; improper container; single buccal swab; wet buccal swab

Collection

Whole blood preferred. Collect specimen in a lavender-top (EDTA) or yellow-top (ACD) tube, or use a buccal swab kit. Ship whole blood specimen at room temperature or frozen. Ship buccal swab collection kit at room temperature.