Use of test
TP53 is one of the genes most frequently mutated in human cancer. Deletions of the TP53 gene can be identified in some patients with chronic lymphocytic leukaemia (CLL), and this has prognostic implications.
Presence of a TP53 deletion is associated with a poorer prognosis in CLL. Presence of a TP53 deletion in relapsed or refractory CLL is prerequisite for PBS access to idelalisib or ibrutinib.
This is an assay for non-heritable mutations. It does not raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient.
Fluorescent in situ hybridisation (FISH) analysis, using probes specific to the TP53 gene.
Requesting the test
0.5 mL bone marrow in transport media, or 5-10 mL blood in lithium heparin.
To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.
We recommend that the patient or another adult check the labelling of request forms and sample tubes.
2 business days.
Note that in cases of relapsed or refractory CLL, TP53 deletion testing has a Medicare rebate.
The Medicare details, including descriptor and schedule fee, are listed under MBS item 73343.