The incidence of radioepidermitis and the dose-response relationship in parotid gland cancer patients treated with 125I seed brachytherapy

Background

We studied the incidence and dose–response relationship of radioepidermitis in parotid gland carcinoma patients treated with [¹²⁵I] seed brachytherapy in the hopes of designing an optimized pre-implant treatment plan that would reduce the incidence and severity of radioepidermitis in patients receiving this therapy.

Patients and methods

Between January 2007 and May 2010, 100 parotid gland cancer patients were treated postoperatively with [¹²⁵I] seed brachytherapy. The matched peripheral dose (MPD) was 80–140 Gy, and [¹²⁵I] seed activity was 0.7–0.8 mCi. The mean dose delivered to the skin was calculated in the post-implant CT on day 0 following implantation. Grades of acute and late dermatitis were evaluated at 2, 6, 12, and 18 months post-implantation.

Results

Most patients experienced grade 0–2 acute and late skin side effects (86 and 97?%, respectively), though a small subset developed severe complications. Most grade 1–3 effects resolved within 6 months of implantation, though some grade 1–3 effects and all grade 4 effects remained unchanged throughout the 18-month follow-up period. Grade 3 and 4 effects were most prominent (75 and 25?%, respectively) with doses of 110–140 Gy; doses higher than 140 Gy produced only grade 4 effects.

Conclusion

[¹²⁵I] seed brachytherapy produced acceptable levels of acute and late radioepidermitis with a good clinical outcome. A mean dose under 100 Gy delivered to the skin was safe, though doses of 110–140 Gy should be given with caution and extra monitoring; doses greater than 140 Gy are dangerous and likely to produce grade 4–5 effects.