The study includes the recruitment of patients with advanced renal cells carcinoma and hepatocarcinoma in treatment with sorafenib. Multicenter cohort study. It is a prospective observational study.

Several tyrosin kinase inhibitors are able to induce hypophosphatemia but the mechanisms underling this metabolic disorder are unknown.

Sorafenib is probably the drug in which this metabolic disturbance is most frequent. The aim of the study is identify variation of blood serum analites involved in hypophosphatemia in patients with advanced renal cells carcinoma and hepatocarcinoma in treatment with sorafenib.

Inclusion Criteria:

1. age over 18 years
2. Histologically documented kidney cancer or hepatocarcinoma
3. Performance status more than / equal to 2
4. Life expectancy > 12 weeks
5. in patients with recent surgery, the wound should be completely healed before taking Sorafenib
6. required initial laboratory values: absolute neutrophil count > 1500/ul Platelets > 100,000/ul., Hemoglobin > 9.0 g/dl, Creatinine, SGOT, SGPT less than 2.0 X upper limit of normal Bilirubin less than/equal to upper limit of normal(ULN)
7. Appropriate patienty compliance

Exclusion Criteria:

1. myocardial infarction or significant change in anginal pattern within the last 6 months, symptomatic congestive heart failure (NYHA Class III or higher) or uncontrolled cardiac arrhythmia,
2. previous history of malignant disease with the exception of non melanoma skin cancer curatively treated,
3. significant neurologic or psychiatric diseases preventing patients to give a valid informed consent
4. Sintomatic brain metastases
5. because patients with immune deficiency are at increased risk of lethal infections when treated with marrow-suppressive therapy, HIV-positive patients receiving combination anti-retroviral therapy are excluded
6. patients with seizures that need medical treatment
7. History of heterologous transplantation
8. Patients with previous or active bleeding
9. Dialysis patients
10. Patients with history of primary hyperparathyroidism
11. Dysphagic patients
12. Taking more than four weeks of entry into the study of other bio-chemotherapy treatments
13. Previous treatment with Sorafenib
14. Recent (<6 months)or concomitant treatment with biphosphonate

Patients with advanced renal cells carcinoma and hepatocarcinoma