Introduction
Purpose
The purpose of this review is to identify the different genomic tests that
are being promoted for clinical use in cancer prevention, diagnosis, and management.
The project was organized into two distinct parts with separate aims and methodologies:
- The goal of Part I was to answer the key question: What genetic tests are
currently available for cancer prevention, diagnosis and treatment?
- The goal of Part II of this project was to answer the key question: What
genetic tests are in development for cancer?
The Centers for Medicare & Medicaid Services (CMS) asked the Agency for
Healthcare Research and Quality (AHRQ) and the Tufts-New England Medical Center Evidence-based
Practice Center to perform a horizon scan of gene-based tests for cancer that are currently
in clinical use, are being promoted for clinical use, or are being developed for
clinical use. CMS has expressed the need for the deliverable to be a ready reference tool to
inform discussions in this area.
Aim
The aim of this horizon scan is to identify the different genomic tests that
are being promoted for clinical use in cancer prevention, diagnosis, and management. As
outlined in the Detailed Workplan, the project was organized into two distinct parts
with separate aims and methodologies. The goal of Part I was to answer the key question:
What genetic tests are currently available for cancer prevention, diagnosis and treatment?
The goal of Part II of this project was to answer the key question: What genetic tests are
in development for cancer?
Definition of a Genetic Test
An essential step early in our project was to establish a definition for genetic
test. To this end, we refer to the Secretary's Advisory Committee on
Genetic Testing (SACGT)'s broad definition:
A genetic test is an analysis performed on human DNA, RNA, genes, and/or
chromosomes to detect heritable or acquired genotypes, mutations, phenotypes,
or karyotypes that cause or are likely to cause a specific disease or condition.
A genetic test also is the analysis of human proteins and certain metabolites,
which are predominantly used to detect heritable or acquired genotypes, mutations,
or phenotypes. The purposes of these genetic tests include predicting risks
of disease, screening of newborns, directing clinical management, identifying
carriers, and establishing prenatal or clinical diagnoses or prognoses in individuals,
families, or populations.1
This definition includes tests for molecular or biochemical biomarkers. It also
includes cytogenetic, genomic, genome-based, and gene-based tests. We have found that
the terms "genetics" and "genomics" are often used
interchangeably in the literature and both can refer to tests for molecular or
biochemical biomarkers, as well as cytogenetic and gene-based tests. This review
will use the term genetics to also mean genomics.
Clinical applications of genetic tests to be covered by the review. Based on our
discussions with AHRQ and feedback from CMS, the following three categories were used
to describe the different applications for the various genetic tests:
- Primary prevention: to detect inherited susceptibility to cancer in persons
who do not have cancer, in order to initiate appropriate interventions (prophylactic
surgery, drug treatment or intensive and earlier screening).
- Secondary prevention: early detection of cancer in persons who have early stage
(asymptomatic) cancer.
- Diagnosis and management: includes confirming cancer, classifying cancer,
predicting typical course of cancer, choosing type of treatment (e.g., surgery alone
or with adjuvant chemotherapy), monitoring response to therapy, choosing the right drug in
the right dose at the right frequency (pharmacogenomics).
- Diagnostic: test used to confirm or aid in the diagnosis of the particular
disease.
- Prognostic: information from the test can be used to determine or predict
the aggressiveness of the disease or overall outcome of the disease, at the time
of initial diagnosis and prior to initiation of treatment. Prognostic information can
then be used to determine a particular or individualized treatment plan.
- Recurrence: to detect disease recurrence in a patient who has already
been diagnosed and treated for cancer. This is a more focused application that
could be considered a subset of tests for the above mentioned "diagnosis
and management" category.
- Monitoring: test used to monitor tumor and/or patient response to treatment.
The focus of this horizon scan was primarily to review the genetic applications
used for disease diagnosis, management and recurrence, and secondarily on disease
prevention.
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