Introduction: Bones are relatively frequent site of symptomatic metastasis in patients with genitourinary malignancies, such as prostate, kidney and urothelial carcinoma. Early detection of skeletal metastasis is very critical for precise staging and optimal management but advanced investigations are not available so easily everywhere. Further imaging and screening for bone metastasis is done if patient is having bony pain or raised serum alkaline phosphatase (ALP). This study is being done to assess the probability of having bony metastasis in urological malignancy on the basis of serum ALP levels and to find out its association in prognosis of urological cancers.
Methods: All the patients who diagnosed with urological malignancy (renal, prostate and urothelial) and underwent bone scan were included in this study. Serum ALP was correlated with the result of bone scan.
Results: During the study period of 30 months, we included 286 patients with 63.4% cases of prostate cancer, 24.4% cases of urothelial malignancy, 11.2% cases of renal carcinoma and 1% case with dual urological malignancies. Around 47.3% patients had metastatic disease on bone scan and most of them were carcinoma prostate (68.4%). Serum ALP was raised in 85.3% cases of bone metastasis and 26.7% of non-metastatic disease. Patients with very high serum ALP (>500 IU/L) have widespread disease with higher number of bony metastatic burden. Sensitivity of serum ALP for bone metastasis was 85.3%, specificity 73.3%, positive predictive value 76.2% and negative predictive value of 83.3%.
Conclusions: Bone scan is very useful screening modality to detect bony metastasis in urological malignancy. Serum alkaline phosphatase (ALP) has got good sensitivity (85.3%) but poor specificity (73.3%), so it cannot be used as surrogative marker for bony metastasis. But patients with very high serum ALP (>500 IU/L) have much higher bony metastatic burden with poor prognosis.
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