Reliability of symptoms to determine use of bone scans to identify bone metastases in lung cancer: prospective study

We read with interest the article by Hetzel et al [1], discussing the
role of bone scans in staging patients with newly diagnosed lung cancer.
We note the high incidence (33%) of bone metastases at presentation. This
may be partly explained by the unusually high proportion of small cell
lung cancer (30%) in the study population; the incidence in the UK and USA
is approximately 15%. The authors suggest that patients may be undergoing
"futile surgery" due to incomplete pre-operative staging. However, it has
been shown that for potentially early stage resectable tumours (T1N0M0 and
T2N0M0), metastases are unlikely to be present in the abscence of clinical
signs [2]. In the abscence of TNM staging for the study population, the
authors cannot claim that a positive bone scan would actually have altered
clinical management.

The implication from the article is that bone scanning may have a
useful role in pre-operative assessment. We would be interested to know
the anatomical location of the bone metastases, particularly whether they
were in the field routinely scanned by staging CT. If this were the case,
were these metastases detected on the staging scan? If there is concern
that patients with potentially operable lung cancer may have occult
skeletal metastases, positron-emission tomography (PET) rather than bone
scanning may have a role in further evaluation of these patients. It has
been shown that PET in preference to standard methods of staging improves
the detection rate of occult distant metastases including bony lesions
[3]. Verboom et al [4] have shown inclusion of pre-operative imaging with
PET is cost-effective in preventing futile operations and indeed
integrated PET-CT improves diagnostic accuracy in comparison to PET or CT
alone [5].

The authors imply that clinical evaluation has a limited role in the
asessment of bone metastases. This is at odds with previous meta-
analyses, which have shown a high negative predictive value for symptoms
and signs [6,7].

The article describes the gold standard as magnetic resonance imaging
(MRI) of the vertebral column together with the patients' subsequent
clinical course. However, there is no mention of the length of clinical
follow-up post bone san. A previous pilot study has shown that MRI may
have a role in detecting occult metastases in potentially resectable
patients particularly in more advanced disease, but this imaging technique
does have a false positive rate [8]. In this study, there is no comment
on the accuracy of MRI or what happened to the cases where there was
discrepancy between MR and bone scan results.

We do not feel this paper provides suffucient evidence to recommend
the routine use of bone scans in the staging of patients with lung cancer.

References

[1] Hetzel M, Hetzel J, Arslandemir et al. Reliability of symptoms to
determine use of bone scans to identify bone metastases in lung cancer:
prospective study. BMJ 2004; 328: 1051-2.

[2] Tanaka K, Kubota K, Kodama T et al. Extrathoracic staging is not
necessary for non-small-cell lung cancer with clinical stage T1-2N0. Ann
Thoracic Surg 1999; 68: 1039-42.

[3] Pieterman R, van Putten J, Meuzelaar J et al. Preoperative
staging of non-small-cell lung cancer with positron-emission tomography.
New Engl J Med 2000; 343: 254-62.

[4] Verboom P, Tinteren H, Hoekstra O et al. Cost-effectiveness of
FDG-PET in staging non-small cell lung cancer: the PLUS study. Eur J Med
Mol Imaging 2003; 30(11): 1444-9.

[5] Lardinois D, Weder W, Hany T et al. Staging of non-small-cell
lung cancer with integrated positron-emission tomography and computed
tomography. New Engl J Med 2003; 348(25): 2500-7.

[6] Silvestri G, Littenberg B, Colice G. The clinical evaluation for
detecting metastatic lung cancer. A meta-analysis. Am J Respir Crit Care
Med 1995; 152(1): 225-30.

[7] Toloza E, Harpole L, McCrory D. Noninvasive staging of non-small
cell lung cancer: A review of the current evidence. Chest 2003; 123(suppl
1): S137-146.

[8] Earnest F 4th, Ryu J, Miller G et al. Suspected non-small cell
lung cancer: incidence of occult brain and skeletal metastases and
effectiveness of imaging for detection--pilot study. Radiology 1999;
211(1): 137-45.

Competing interests:
None declared