There are several shortcomings to
There are several shortcomings to this study that need to be considered. The small size of this series is an obvious shortcoming. Due to the relative rarity of the disease, this problem is not unique to this series and authors of a recent meta-analysis noted the small sample size of other studies as an obstacle in drawing firm conclusions regarding prognostic implications of LDH in terms of survival. The small number of patients without metastases in this series would adversely affect the ROC analysis and therefore the suggested cut-off values. Numerous patients were lost to follow-up in our series and the long-term survival could not be determined. The cohort of patients in our series is also not directly comparable to those in other studies. The incidence of metastases (80%) at time of diagnosis were much higher than the 14% reported by Bacci et al. Furthermore, the mean tumour volume in this series was much higher than in previous reports . These factors suggest that the cancer was either more advanced, both locally and systemically, or more aggressive in nature in our series of cases. The higher incidence of metastases in this series did however enable us to determine more sensitive cut-off points for the proposed prognostic indicators. Our results suggest that the sensitivity of ALP and LDH in predicting the presence of skeletal metastases may be improved by using a cut-off point of 75 IU/L and 450 IU/L, respectively.
The findings of this study should be borne in mind during the initial staging and follow-up of a patient presenting with osteosarcoma. 18F-fluorodeoxy-d-glucose (FDG) positron emission tomography (PET) has been found to be more sensitive in the detection of skeletal metastases from sarcomas . The sensitivity and specificity of spiral CT (computed tomography) however remains superior to FDG-PET in the detection of lung metastases . In cases of osteosarcoma with LDH >850IU/L and/or ALP >280IU/L at presentation it cholinesterase inhibitors may thus be prudent to consider spiral CT and FDG-PET in the initial systemic staging of the patient. In addition, the follow-up of patients who present with a high ALP and/or LDH should possibly also be more rigorous. ESMO currently recommends the use of X-rays or CT scan in the follow-up of patients . However, thought should be given to the use of spiral chest CT and FDG-PET or technetium bone scintigraphy during the follow-up patients with high LDH and ALP levels in order to detect metastases early.
Acknowledgements R.R. is supported by the National Research Foundation of South Africa (Grant no. 95733) and The Colleges of Medicine of South Africa (Grant no. 12106).
Background The incidence of bone metastases (BM) in advanced non-small-cell lung cancer (NSCLC) patients is estimated to range from 30% to 40% [1,2]. The presence of BM often results in pathologic remodeling of the affected bone compartment, making affected bones vulnerable to skeletal related events (SREs). SREs include pathologic fractures, spinal cord compression, requirement for radiation, surgery to bone and hypercalcemia, all reducing quality of life and worsening prognosis . BM is a poor prognostic survival factor . Therefore, early diagnosis and adequate treatment of BM is critically important issues of the clinical management of NSCLC patients. To detect BM in NSCLC patients, bone scintigraphy combined with plain radiographs, computerized tomography (CT) and magnetic resonance imaging (MRI) is recommended. But routine radiography only gives definite diagnosis when the bone is already substantially damaged by the tumor. Although scintigraphy is more sensitive, its specificity is not satisfactory due to pseudo-positive values caused by inflammation and traumatic fracture. Any abnormal scintigraphic findings should always be verified by radiographic ones . Bone scintigraphy is also a more expensive, invasive, time-consuming, and exposes cancer patients to irradiation, limiting its use for monitoring purposes.