The role of radiotherapy in the management of multiple myeloma

Local radiotherapy for palliation in multiple myeloma patients with symptomatic bone lesions

Purpose

To evaluate the clinical outcomes of symptomatic bone lesions in patients with multiple myeloma (MM) who received local radiotherapy (LRT).

Materials and Methods

Fifty-one patients with 87 symptomatic bone lesions treated via LRT were analyzed. LRT was delivered at a median total dose of 21 Gy (range, 12 to 40 Gy) in a median of 7 fractions (range, 4 to 20 fractions). The clinical outcomes of LRT and the factors affecting treatment response were assessed.

Results

After a median follow-up time of 66.7 weeks, symptom relief was achieved for 85 of 87 lesions (97.7%). The median time to symptom relief was 7 days from the start of LRT (range, 1 to 67 days). The duration of in-field failure-free survival ranged from 1.1 to 450.9 weeks (median, 66.7 weeks). The radiation dose or use of previous and concurrent chemotherapy was not significantly associated with in-field failure for LRT (p = 0.354, 0.758, and 0.758, respectively).

Conclusion

Symptomatic bone lesions in patients with MM can be successfully treated with LRT. A higher radiation dose or the use of concurrent chemotherapy may not influence the in-field disease control. A relatively low radiation dose could achieve remission of symptoms in patients with MM.

Myeloma bone disease

The major clinical manifestation of multiple myeloma is related to the osteolytic bone destruction. The bone disease can lead to pathologic fractures, spinal cord compression, hypercalcemia, and pain. It is also a major cause of morbidity and mortality in these patients. These patients frequently require radiation therapy, surgery and analgesic medications. Bisphosphonates are specific inhibitors of osteoclastic activity, and these agents have been evaluated in myeloma patients with bone disease during the past 15 years. Several large randomized trials have been conducted in myeloma patients also receiving chemotherapy. Orally administered bisphosphonates have shown little ability to slow the development of skeletal complications in these patients. In contrast, more potent intravenous monthly infusions of either pamidronate or zoledronic acid have reduced the skeletal complications among these patients and are now a mainstay of myeloma therapy. A number of other types of new anti-bone-resorptive agents are also in early clinical development.

Bone disease in myeloma

The major clinical manifestation of multiple myeloma results from osteolytic bone destruction. The only currently Food and Drug Administration-approved drug for the treatment of the bony complications of multiple myeloma is monthly intravenous pamidronate at a dose of 90 mg infused over 4 hours. Recent studies have shown the safety of 2-hour infusions. A randomized trial comparing pamidronate to placebo continued to show benefits throughout the 21-month trial. Although the duration of therapy has not been firmly determined, it is likely that discontinuation of this drug will be met by enhanced bone loss and an increased risk of bony complications for these patients. Thus, it is recommended that the drug be continued indefinitely. Support for this recommendation also comes from the reduced bone density observed in women with postmenopausal osteoporosis following the withdrawal of bisphosphonate treatment. Recent attempts to give higher doses, more frequent infusions (every 2 weeks or less), or more rapid infusions (1 hour or less) of pamidronate have occasionally been associated with albuminuria and azotemia. These modifications should therefore be avoided. Importantly, the drug can be safely administered at 90 mg monthly to patients with poor renal function. The use of pamidronate for myeloma patients without lytic bone involvement or with Durie-Salmon stages I or II disease has not been evaluated. However, it is recognized that most patients with earlier stages of disease or without lytic bone involvement also develop bony complications. There is no reason to believe that these patients would not benefit from monthly intravenous infusions of pamidronate. The potential antimyeloma effect of this agent is another reason to administer this drug in these types of patients. Thus, it is our practice to administer monthly pamidronate to myeloma patients regardless of stage or bone involvement. However, trials evaluating oral bisphosphonates have produced inconsistent clinical results, probably as a result of the erratic and scanty poor absorption as well as poor oral tolerability of these drugs. Although these oral agents may be useful in some patients, it is impossible to identify which myeloma patients will benefit from orally administered bisphosphonates. The more potent nitrogen-containing bisphosphonate zoledronic acid more effectively reverses hypercalcemia of malignancy than pamidronate, and it appears promising in reducing bone loss in cancer patients. However, its efficacy in preventing skeletal complications is still being evaluated. Many other types of new agents are in early clinical trials, but their efficacy remains unproven at the present time.

Double hemibody irradiation (DHBI) in the management of relapsed and primary chemoresistant multiple myeloma

In view of increasing controversy regarding the role of double hemibody irradiation (DHBI) in the treatment of multiple myeloma, we have analysed the use of this technique at our institution over a 6-year period. Fifty-five patients with multiple myeloma were treated with both upper and lower hemibody irradiation between January 1985 and January 1991; 42 had relapsed post-plateau and 13 were chemoresistant to initial therapy. Fifteen patients received alpha IFN-2b maintenance therapy post-DHBI, at a dose of 3 Mu three times per week, as part of a randomized trial. Ninety-five per cent of patients experienced symptomatic improvement in bone pain post-DHBI, 21% of whom discontinued opiate analgesics altogether; 63% had a minor biochemical response and 38% had a partial biochemical response. The overall survival (OS) and progression free survivals (PFS) in all patients were 11 months and 8 months respectively. No significant difference was noted in either OS or PFS, according to whether patients were chemoresistant or had relapsed post-plateau. alpha IFN did not appear to prolong survival (OS or PFS) post-DHBI. Cytopenia was a significant problem, such that only 60% of patients had counts adequate enough to be eligible for alpha IFN. We conclude that DHBI is an effective treatment in patients with relapsed multiple myeloma and in those who are chemoresistant to initial therapy.(ABSTRACT TRUNCATED AT 250 WORDS)