gms | German Medical Science

27th German Cancer Congress Berlin 2006

German Cancer Society (Frankfurt/M.)

22. - 26.03.2006, Berlin

Radiotherapy of head and neck during long-term bisphosphonate treatment

Meeting Abstract

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27. Deutscher Krebskongress. Berlin, 22.-26.03.2006. Düsseldorf, Köln: German Medical Science; 2006. DocIS003

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Published: March 20, 2006

© 2006 Adamietz.
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Advancing the treatment for head and neck malignancy is always high on the agenda of clinical investigation in radiation oncology. Radiation therapy and surgery continue to play the central roles in local, curative management, and improvements in radiotherapy and systemic agents have improved outcomes for patients with advanced, unresectable disease. Chemoradiotherapy has been shown in randomized controlled trials to provide better outcomes in certain head and neck cancer situations. Radiotherapy is also an effective treatment for metastatic bone disease. However, very few areas of radiation oncology practice induce major, life altering normal tissue consequences so routinely. Osteoradionecrosis (ORN=a condition of nonvital bone in a site of radiation injury) may occur in patients after irradiation. ORN can be spontaneous, but it most commonly results from tissue injury. The absence of reserve reparative capacity is a result of the prior radiation injury. The mandibular region is highly susceptable to bone necrosis. Bisphosphonates (BPs) have been shown to decrease pain, skeletal fractures and other complications associated with bone metastases and are widely used in metastatic bone disease. Treatment of bone metastases, in many instances, involve continued use of BP for a number of years. BPs normalize bone turnover rates within weeks and no further suppression is seen during long term use, documented up to 10 years. This indicates that the BP retained in bone does not augment or contribute to the pharmacological activity of newly administered BP. Therefore, pharmacologically, long term treatment is not different from short term treatment. Multiple studies have shown that reductions in bone turnover are associated with increased bone density, more homogeneous mineralization, and reduced fracture risk. The amount of BP retained in bone is small. This small fraction, which is unevenly distributed between cancellous and cortical bone, seems unlikely to change bone mechanical properties. Taken together, the known mechanism of action of potent BPs and the experience accrued from treating a large number of patients, including long follow-ups in controlled trials, have identified only beneficial BP effects on bone. However, there are reports of microdamage accumulation and reduction of bone elasticity after long-term use of bisphosphonates. Therefore an elevated risk of bone necrosis may be expected in the irradiated mandibular area in patients receiving long term bisphosphonate treatment.