overestimating the rate of metastasis.303132 Nevertheless, it is correct to assume based on the
random clinical trial evidence that the rate of metastasis will not be the same in both N0/1 and
N2/3 patients. Therefore, I will also test the NICE underlying distribution for lung cancer to
see if this has any effect on the model this is giveen table 3 below.
Table 3: NICE distribution for NSCLC
|
N0/1, M0 |
N0/1, Ml |
N2/3, M0 |
N2/3, Ml | |
|
Normal lymph nodes |
56.98 |
1.794 |
3.4 |
5.82 |
|
Enlarged lymph |
17.02 |
6.006 |
5.1 |
3.88 |
Life expectancy and QALYs
The quality adjusted life year (QALY) is constructed by attaching utility weights to life
expectancy data with 1 being equivalent to full health and 0 being dead. The possible values
between full health and death are then ranked on the unpleasantness to be in that health state
providing the QALY weights.33 However, it was not possible to find any Australian utility
values associated with NSCLC.
Furthermore, there is a lack of data on the utilities of patients with NSCLC overall and
the data that is used here is not of the highest quality. There is no data on the utilities of
patients who receive futile operations or radiotherapy, chemotherapy or other supportive care
for N0/1, N2/3 or M1 diseases. The model here is based upon the values used in the HTBS
model; this is because no newer or better estimation of QALYs were found.
It has been suggested that patients experience reduced quality of life when they
undergo surgery in terms of discomfort and anxiety, Therefore it was assumed that undergoing
surgery results in a lost of quality of life and in this model it has taken the literature value of
0.15 undergoing surgery. But this is based on estimation and therefore major uncertainty
surrounds this value.34 Furthermore, the NICE study suggests that undergoing radical
radiotherapy should also result in a reduction in quality of life, but to avoid putting any more
uncertain assumptions into the model it was assumed that undergoing radiotherapy here did not
result in any loss of quality of life. 34
Table 4. Model Inputs for the model
30 Herder, G. J., H. Kramer, et al. (2006). "Traditional versus up-front [18F] fluorodeoxyglucose-positron
emission tomography staging of non-small-cell lung cancer: a Dutch cooperative randomized study." J Clin Oncol
24(12):
31 Viney, R. C., M. J. Boyer, et al. (2004). "Randomized controlled trial of the role of positron emission
tomography in the management of stage I and II non-small-cell lung cancer.[see comment]." Journal of Clinical
Oncology 22(12):
32 van Tinteren, H., O. S. Hoekstra, et al. (2002). "Effectiveness of positron emission tomography in the
preoperative assessment of patients with suspected non-small-cell lung cancer: the PLUS multicentre randomised
trial." Lancet 359(9315):
33 Hunink, M et al, Decision making in Health and Medicine: Integrating evidence and values, Cambrdige, C.U.P,
2001. p.97.
34 National Institute of Health and Clinical Effectiveness, “The Diagnosis and treatment of Lung Cancer; Methods,
Evidence and Guidance. National Collaboration Centre of Acute Care. 2005. Appendices p.272.
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