FRIDAY, Jan. 31, 2020 (HealthDay News) — For patients with multiple myeloma receiving focal radiation therapy (RT) for symptomatic plasmacytoma, reirradiation is rarely required, according to a letter to the editor published online Jan. 9 in Haematologica.

Adnan Elhammali, M.D., from the University of Texas MD Anderson Cancer Center in Houston, and colleagues identified all patients aged ≥18 years with a diagnosis of multiple myeloma who were treated with RT from 1999 through 2017. A total of 772 patients treated with RT to 1,513 sites were included; patients were followed for a median of 65.6 months.

The researchers found that the most commonly treated site was the spine (39.4 percent); most patients were treated at a single site (55.9 percent), while 22.9 and 21.4 percent were treated at two sites and three or more sites, respectively. The median biologically effective dose (BED) was 28.8 Gy10. Overall, 2.6 percent of the 1,513 sites treated underwent reirradiation, with the most common reasons being persistent pain and radiographic progression (90 and 80 percent, respectively). A small but statistically significant increase in reirradiation rates was seen for a BED ≤28 Gy10 (3.25 versus 1.83 percent; hazard ratio, 6.16). After completion of the first course of RT, the median overall survival was 25.6 months, and the one-, three-, and five-year overall survival rates were 66.5, 42.0, and 33.5 percent, respectively.

“Dose escalation to a BED of at least 28 Gy is recommended when durable local control is desired,” the authors write.

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