Photodynamic therapy for the treatment of metastatic lesions in bone: Studies in rat and porcine models

In order to substantiate our hypothesis that Photodynamic therapy could be used effectively to treat metastatic disease in bone, we investigated this with both in vitro and in vivo models using the human metastatic breast cancer cell line, MT-1.13 A bioluminescent metastatic model in the nude rat was developed to facilitate the localization, targeting, and progression of lesions prior to and following PDT treatment

S. Burch

2005

Scholarcy highlights

  • Over 100,000 bone metastases are identified in North America each year and of those an estimated 30–40,000 cases of metastatic breast cancer lesions occur in the spine
  • Cancer in bone is often accompanied by very poor prognosis for long-term survival beyond 1–2 years, depending on the primary malignancy
  • The chronic morbidity associated with spinal metastases, can be the defining factor predicting survival with intractable back pain due to lesions in one or more vertebral bodies encroaching onto the spinal cord, loss of bowel and bladder function, paresis, and paralysis
  • That cells and tissues can rapidly develop resistance to radiation upon subsequent re-treatment(s) making the initially prescribed dose quickly ineffective with little option for elevating the dose due to the impending risk of myelopathy and/or bone fracture. Both of these factors contribute to the high incidence of recurrence, an estimated 33%, of patients with spinal metastases,122 which is further exacerbated by an increased longevity of patients with spinal metastases
  • Targeted lesions treated with 25 J of light with a 3 h drug light interval showed a decrease in tumor growth of 66% compared to that of the control lesions
  • radiation therapy is known to increase the morbidity of surgical intervention by as much as threefold, a procedure that is already associated with a 30–40% risk of morbidity and a 7–16% risk of mortality
  • The evaluation of light transmittance through the vertebral body in a pig model reinforces the potential for fiber-based, nonthermal light delivery into bone for targeting lesions up to 2 cm or greater from the treatment fiber without damaging the spinal cord

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