A more recent study by Johnson et al. ( 2015 ) reported important financial benefits
stemming from the use of genotype-guided antiplatelet therapy, which reserves
prasugrel or ticagrelor only for patients with reduced CYP2C19 activity, hence
avoiding costs associated with adverse cardiac events in this patient group.
Furthermore, studies have shown that adding trastuzumab to adjuvant chemo-
therapy of patients with HER2-positive breast cancer improves patient survival and
reduces the risk of distant metastases, as reviewed by Garnock-Jones et al. ( 2010 )
and Phillips et al. ( 2009 ). As a result of the HER2 diagnostic test, physicians can
administer chemotherapy and trastuzumab to all patients with a HER2-positive test
result and chemotherapy only to patients with a HER2-negative test result, instead
of treating all patients with chemotherapy and trastuzumab or treating all patients
with chemotherapy only. Several studies, such as Dedes et al. ( 2007 ) and Skedgel
et al. ( 2013 ), have evaluated the cost-effectiveness of trastuzumab in patients with
HER2-positive cancer and found that the treatment strategy can generally be
considered cost-effective. Although the evidence on real-world cost-effectiveness
of testing strategies is still limited, clinicians’ability to accurately identify appro-
priate therapeutic candidates using HER2 testing is an important factor in deter-
mining the effectiveness and cost-effectiveness of trastuzumab therapy.^31 Ferrusi
et al. ( 2009 ) also demonstrated that the choice of the test and test sequencing can
influence the cost-effectiveness of trastuzumab treatment by reducing the number
of false-positive and false-negative HER2 diagnoses.
Finally, Behl et al. ( 2012 ) report on the results of cost-effectiveness analysis of
screening for KRAS and BRAF mutations in metastatic colorectal cancer. In case of
metastatic colon cancer patients who are candidates for antiepidermal growth factor
receptor (EGFR) therapy, a biomarker can be used to predict how the cancer will
respond to therapy. The biomarker, which is a protein encoded by the KRAS gene,
can now be detected through a simple diagnostic test. The test is important because
tumors with KRAS mutations do not respond to anti-EGFR therapy. Hence, if
physicians limit the anti-EGFR therapy only to patients without KRAS mutations,
they will avoid unnecessary costs and harm to patients who cannot benefit from the
treatment. If the screening test for KRAS mutation is not administered alongside
anti-EGFR therapy, this increases treatment costs by approximately $7500 per
patient, according to Behl et al. ( 2012 ). Hence, screening for KRAS improves the
cost-effectiveness of anti-EGFR therapy, although the incremental cost-
effectiveness ratio is higher than (what authors assume to be) the accepted thresh-
olds for evaluating cost-effectiveness in the US (i.e., US$100,000).
(^31) As discussed by Phillips et al. ( 2009 ), pp. 5166–5174, and Ferrusi et al. ( 2009 ), pp. 193–215.
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