Different Levels of Alkaline Phospatase (ALP) in Multiple Myeloma (MM) and SOLID Tumors with BONE Lesions

Background: alkaline phosphatase (ALP) is an enzyme localized in different tissues and its levels may increase in diseases with skeletal involvement.

Aim: To compare ALP levels in patients with Multiple Myeloma and osteolytic lesions, and in patients with solid tumors (breast, prostate, lung, stomach, kidney and colon) and osteolytic, osteoblastic and mixed (osteolytic and osteoblastic) bone metastatic lesions.

Patients and Methods: From 1991 we collected 400 patients with MM and 308 patients with solid cancer with bone involvement. We grouped patients according to the metastases type (osteolytic, osteoblastic mixed), number of metastasis (1, 2-3, more than 3), ISS and D&S Stage. Among patients with solid tumors 45% had lytic lesions, while 31,5% had osteoblastic lesions and 23,5% had mixed lesions. Comparing MM vs. bone metastasis from solid cancer respectively 64.5% vs. 59% had normal ALP values, while 29% vs. 28% had <2xUNL, and 6.5% vs. 13% had >2UNL values of ALP. Patients with MM had significantly lower ALP values when compared to patients with osteoblastic bone lesions (P<0.05). In particular, comparing ALP levels of MM patients with the levels observed in cancer patients with >3 osteoblastic lesions difference is even more significant (P<0.01). Moreover, patients with Breast and Prostate cancer had ALP values significantly higher than MM pts (P<0.05 and P<0.05 respectively).In the group of patients with solid tumors, ALP levels were significantly higher in those with >3 osteoblastic lesions than in those with only osteolytic lesions (P<0.05).

Conclusion: These preliminary results indicate that ALP should be part of the initial work up in pts with bone lesions. This simple and cheap test, if normal or reduced in presence of osteolytic bone lesions, suggests an initial complete protein study including serum and urine protein electrophoresis associated to Bone Marrow aspirate, in case of the presence of a paraprotein.