1 Breast Unit and 2 Clinical Oncology, University of Udine, Udine, Italy
* Correspondence to: Dr F. Puglisi, Clinica di Oncologia Medica, Policlinico Universitario, Piazzale SM Misericordia, 33 100 Udine, Italy. Tel: +39-0432-559304; Fax: +39-0432-559305; Email: fabio.puglisi{at}med.uniud.it
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Abstract |
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Methods: We selected the study sample from 516 consecutive patients with newly diagnosed invasive breast cancer. For each diagnostic test (BS, LUS, CXR), we analyzed the prevalence defined as the number of patients with diagnosis of metastatic disease after an imaging technique divided by the total number of patients tested. In addition, sensitivity and specificity were calculated. Initial suspicion was confirmed by other independent tests (bone X-ray, computerized tomography scan, magnetic resonance imaging) in order to identify true positive diagnoses.
Results: At baseline, BS was carried out in 412 patients, LUS in 412 patients and CXR in 428 patients. Thirty-three patients were correctly diagnosed by the initial staging investigations as having metastatic disease (true positive cases). BS detected skeletal metastases in 6.31% of patients, LUS detected liver metastases in 0.72% of patients and CXR detected lung metastases in 0.93% of patients. Before imaging tests, all patients with either LUS or CXR evidence of metastases were previously classified as having stage III disease. On the other hand, only 26.9% of bone metastases were detected in patients with stage III. Accordingly, the detection rate in stage III patients was 14%, 5.6% and 7.2%, respectively for BS, LUS and CXR.
Conclusions: These findings indicate that a complete diagnostic work-up to detect metastases is unnecessary in the majority of patients with newly diagnosed breast cancer, whereas it may be indicated for specific patient categories such as those with stage III disease.
Key words: baseline staging, bone scan, breast cancer, chest radiography, liver ultrasonography
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Introduction |
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In patients with breast cancer, correctly staging the disease is important in guiding patients and physicians towards the most appropriate treatment option, namely to decide in favor of loco-regional versus systemic therapy [1, 2
].
Traditionally, and according to the most common sites of metastases, non-invasive radiological tests routinely employed in the staging work-up for breast cancer have included bone scanning (BS), liver ultrasonography (LUS) and chest radiography (CXR). However, the yield of these tests has gradually scaled down after several studies reporting their inappropriateness especially in determinate subgroups of patients, such as those with small tumors and absent or minimal involvement of the axillary nodes [3, 4
]. In fact, the use of these radiological tests in all breast cancer patients is unnecessarily expensive and time consuming. In addition, false positive results of the tests that require additional confirmatory examinations [computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography] may cause anxiety in patients and increase costs.
Nonetheless, many oncologists and breast surgeons probably continue to routinely order these tests as part of the baseline work-up. In addition, although with different implications and significance, the staging process by BS, LUS and CXR is always requested before enrolling a patient in a clinical trial. Furthermore, no official guidelines on this topic have been set out to date by the leading professional societies, such as the American Society of Clinical Oncology (ASCO) or the European Society of Medical Oncology (ESMO). Instead, ASCO clinical guidelines for breast cancer surveillance do not recommend serial imaging tests following primary intervention [5].
In order to add another piece of evidence on this topic, we reviewed findings about staging procedures from our database of breast cancer patients. In addition, unlike previous studies, we considered in the analysis some preoperative variables such as radiological size of the tumor, histological grade and hormonal receptor status on core biopsy, and the preoperative value of tumor marker CA 15.3. These variables together with others analyzed after surgery (pT, pN, tumor size) were assessed to identify specific subgroups of patients with a higher risk of metastatic disease (higher pre-test probability).
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Patients and methods |
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For each staging procedure, we analyzed the prevalence defined as the number of patients with diagnosis of metastatic disease after an imaging technique divided by the total number of patients tested. In addition, sensitivity (true positive results/true positive results + false negative results), specificity (true negative results/true negative results + false positive results) and positive predictive value (PPV: true positive results/true positive results + false positive results) were calculated. For the analysis, results categorized as suspect by the staging tests were computed as positive (higher sensitivity and lower specificity are therefore expected). Initial suspicion was confirmed by other independent tests as appropriate in order to identify true positive diagnoses. In particular, bone scan abnormalities were evaluated by bone X-ray and/or CT scan and/or MRI. Abnormal LUS results were evaluated by CT scan and/or MRI. CXR abnormalities were studied by CT scan. Cases in which the diagnosis was not conclusive after further investigations were monitored for at least 6 months.
Associations between categorical variables were evaluated using the chi-square test or Fisher's exact test as appropriate. The nonparametric MannWhitney rank sum test was used for comparison of groups with ordinal data.
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Results |
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Discussion |
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In addition, Chen et al., in a large study (n=1493) designed to identify patients with early breast cancer who were upstaged to stage IV by a CXR, demonstrated a pulmonary metastasis prevalence of 0.099% in asymptomatic patients [7].
In a more recent paper, Ravaioli et al. reviewed data about staging procedures on 1218 breast cancer patients [3]. An overall prevalence of 1.46% was reported when results of BS, LUS and CXR were analyzed together in patients with low risk tumor characteristics (pT1T3 and a number of positive nodes
3). On the other hand, in patients belonging to the high risk group (pT4 or a number of positive nodes >3 or pN2), the prevalence was 10.68%.
The authors concluded that new recommendations for the staging of breast cancer should be formulated, suggesting the use of BS, LUS and CXR only in patients with an a priori high risk of metastases.
Our study compares well with the data in the literature: patients with AJCC stage I and II breast cancer should not be routinely staged by LUS and CXR at baseline. In fact, the prevalence of liver and lung metastases detected by imaging techniques is equal to zero in the presence of early stage disease and dramatically increases in patients with stage III tumors (Table 3). Interestingly, in our series, a few cases of skeletal metastases were still diagnosed in stage I and II (prevalence of 5.08% and 5.55%, respectively), but no predictors were found to discriminate, better than stage, cases with higher risk of bone metastases.
The aim of our study was also to evaluate whether some preoperative variables such as radiological tumor size, tumor marker Ca 15.3, tumor grade on core biopsy or hormonal receptor status could predict the chance of detecting distant metastases. The availability of such earlier predictors should be very useful to avoid unnecessary surgery in patients with imaging confirmed metastatic disease. We found only a marginal association between higher values of Ca 15.3 and bone metastases and between higher tumor grade on core biopsy and liver metastases. These findings, however, must be interpreted with caution due to the limited sample size.
In conclusion, our study strengthens the recommendation to limit baseline staging tests, especially LUS and CXR, to patients at higher risk (stage III) of distant metastases. An indiscriminate use of diagnostic procedures in all patients with newly diagnosed breast cancer has a high chance of generating unjustified anxiety in patients and of increasing costs.
Finally, the unproven effectiveness of these tests in routine follow-up casts doubt upon their usefulness as a baseline reference [5].
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Acknowledgements |
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Received for publication July 12, 2004. Revision received October 21, 2004. Accepted for publication October 22, 2004.
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References |
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