The value of TNM tumour staging and serum alkaline phosphatase levels in predicting the presence of bone metastases in patients with renal cell carcinoma

Summary 

Objectives

To determine if the TNM tumour staging and serum alkaline phosphatase levels (SAP) can be used to identify which patients with renal cell carcinoma (RCC) are at greatest risk of osseous metastases.

Patients and methods

A retrospective review of patients with histologically proven RCC was conducted. All patients had initial CT or MRI staging scans of the chest and abdomen. Patients also underwent bone scintigraphy and all abnormal areas were further evaluated with either serial or collaborative imaging to determine their nature.

Results

91 patients including 66 men and 25 women, with a mean age of 61, were included in the study. The incidence of bone metastases was 17.6%. The incidence of bone metastases in T1-4 disease was 4%, 31.3%, 31.8% and 66.7%, respectively. Patients with >T1N0M0 disease, as defined by initial staging scans, accounted for 53% of the cohort and included all instances of proven osseous disease. Thus ‘>T1N0M0’ was 100% sensitive and 57.3% specific as a predictor of bone metastases. Conversely, a raised SAP (>129U/L) was only 25% sensitive but had a specificity of 94.3%.

Conclusions

Patients with >T1N0M0 staging should undergo bone scintigraphy. SAP is a far less sensitive predictor and its concurrent use is unwarranted.

Keywords: Renal cell carcinoma, RCC, Bone scintigraphy, Metastases