Radiation Therapy - Palliation

Among the sites of systemic failure most prevalent in patients with breast cancer, brain and bone metastases are very adequately treated with brief courses of radiation. In certain circumstances, surgical excision of a solitary brain metastasis followed by whole-brain irradiation can prolong survival compared with that of patients who do not undergo surgical resection.

Therefore, for the patient who appears to have a solitary metastasis on CT, a gadolinium-enhanced MRI would be indicated to evaluate the patient's candidacy for craniotomy. The patients who do the best, with median survivals as long as 21 months, are those who have systemic disease under control.

Therefore, this radical approach to brain metastases, particularly solitary metastases, should not be eliminated from consideration.

For patients with bone metastases, radiation can provide very reliable palliation. We usually employ a fractionation scheme of 30 Gy in 10 fractions, which permits the completion of therapy in 2 weeks time. Ordinarily, patients do not begin to feel any meaningful improvement until halfway through the course of radiation, and the maximal effectiveness is expected approximately 1 month after therapy is completed. Bone metastases from breast cancer are a significant cause of morbidity. Palmidronate therapy is a valuable adjunct to prevent fractures.

When an impending fracture is identified in a weight-bearing bone, either prophylactic pinning or irradiation with limited weight bearing is indicated. In this situation, the early involvement of an orthopedic consultant to evaluate the need for prophylactic surgical fixation is mandatory.

In the case of vertebral metastases causing spinal-cord compression, there appears to be no advantage to approaching these patients with surgical intervention at the time of diagnosis.

Patients are pretreated with dexamethasone, then commence with radiation utilizing a dose fractionation scheme of 30 Gy in 10 fractions. The patient's neurologic status must be carefully monitored and the dexamethasone tapered as tolerated. The majority of patients with spinal-canal compromise can be adequately managed and have neurologic disability averted utilizing this technique. The practitioner must be vigilant for early signs of spinal-cord compression that may initially manifest as back pain. An MRI is invaluable in the evaluation of these patients. It is also extremely valuable in the planning of radiation fields to include other nearby sites of subclinical disease.

Paradoxically, planning palliative radiation fields for bone metastases requires restraint as numerous subclinical lesions that are unlikely to cause symptoms during the patient's lifetime are frequently visualized. Fields that are designed significantly larger than is necessary to achieve the goal of palliation will compromise the patient's ability to tolerate systemic chemotherapy. All areas of irradiated bone will have a severely diminished ability to support hematopoiesis after irradiation. Therefore, careful consideration must be utilized when designing palliative fields for bone metastasis.