From the Guidelines
Elevated alkaline phosphatase (ALP) levels are associated with an increased risk of bone cancer, particularly osteosarcoma, and should be considered a prognostic factor in the diagnosis and treatment of this disease. ALP is an enzyme produced by various tissues, particularly bone and liver, with bone-specific ALP increasing during periods of active bone formation or destruction [ 1 ]. In bone cancer, especially osteosarcoma and bone metastases, tumor cells can stimulate excessive bone turnover, causing ALP levels to rise significantly above the normal range of 20-140 IU/L. However, ALP elevation alone is not diagnostic of bone cancer, as it also increases in benign conditions like Paget's disease, healing fractures, and normal growth in children.
When evaluating potential bone cancer, doctors typically monitor ALP alongside other markers such as calcium levels, specific bone turnover markers, and imaging studies [ 1 ]. A persistent elevation of ALP with other suspicious clinical findings warrants further investigation through bone scans, X-rays, CT scans, or biopsies. The degree of ALP elevation may correlate with tumor burden and can be useful for monitoring treatment response, with decreasing levels potentially indicating effective therapy [ 1 ]. Regular ALP monitoring during cancer treatment helps assess disease progression and therapeutic efficacy.
Some key points to consider in the relationship between ALP and bone cancer include:
- Elevated serum AP is an adverse prognostic factor in osteosarcoma [ 1 ]
- ALP levels can be used to monitor treatment response and disease progression [ 1 ]
- A combination of ALP and other markers, such as LDH, can provide valuable information for diagnosis and prognosis [ 1 ]
- Imaging studies, such as bone scans and CT scans, are essential for diagnosing and staging bone cancer [ 1 ]
From the Research
Alkaline Phosphatase and Bone Cancer Relationship
- Alkaline phosphatase (ALP) has been found to be a valuable tumor marker with high specificity in osteosarcoma, as shown in a study published in 2017 2.
- Elevated ALP levels at diagnosis have been associated with inferior overall survival and disease-free survival in patients with osteosarcoma 2, 3, 4.
- The sensitivity and specificity of ALP on diagnosis were 53.2% and 90.1%, respectively, and the sensitivity of ALP on metastasis was 53.2% with a specificity of 78.2% at 15 months postoperative and 90.0% at 3 years postoperative 2.
- A meta-analysis published in 2017 found that higher levels of ALP can decrease the overall survival and event-free survival in patients with osteosarcoma, with a pooled hazard ratio of 1.78 for overall survival and 1.58 for event-free survival 4.
Prognostic Value of Alkaline Phosphatase
- Pre-chemotherapy ALP levels have been found to be correlated with survival, with normal or high pre-chemotherapy ALP levels associated with better survival at 10 years 3.
- Post-chemotherapy ALP levels have also been found to be correlated with survival, with normal post-chemotherapy ALP levels associated with better survival 3, 5.
- A decrease in ALP levels during the first month of neoadjuvant chemotherapy has been found to be a predictive indicator of tumor necrosis and clinical outcome in patients with osteosarcoma 5.
Alkaline Phosphatase in Cancer Diagnosis and Treatment
- Alkaline phosphatase has been found to have potential in the diagnosis, prognosis, and treatment of tumors, including osteosarcoma, liver cancer, and pancreatic cancer 6.
- Combined detection of ALP and other biomarkers, such as aspartate aminotransferase and bone-specific alkaline phosphatase, may be used for more accurate diagnosis of a particular tumor 6.