Phase 1 Dose Escalation Trial Using Stereotactic Body Radiation Therapy (SBRT) for Partial Breast Irradiation (PBI)

Abstract

analyze the impact of serum TGF-b 1 and IL-8 level on radiation-induced skin toxicity. Materials/Methods: From January 2, 2011 to June 20, 2012, 80 patients were enrolled in this prospective trial. Patients were randomized as concurrent group (n Z 40) in which hormonal therapy with anastrozole 1mg per day combined concurrently with radiation therapy, and sequential group (n Z 40) in which hormonal therapy with anastrozole were followed after completion of radiation therapy. Both groups were balanced in age, surgical types, and TN staging. Treatment outcomes, acute toxicity and serum TGF-b 1 and IL-8 levels (before and 4 weeks after the start of radiation therapy) were followed up and analyzed. Results: The median age of the 80 patients was 58 yrs (49w72 yrs). The percentage of stage I, II and III was 12.5%, 22.5% and 65% in the concurrent group and 12.5%, 37.5% and 50% in the sequential group, respectively. The median follow-up time was 24 months (12w34 months). Five patients in the concurrent group and seven patients in the sequential group developed grade 2 or worse acute skin-related toxicity, the difference between two groups was not statistical significant (P > 0.05). The incidence of hematologic toxicity of two groups was no statistically significant difference (P > 0.05). There was no symptomatic radiation pneumonitis in two groups. The overall survival was 100% in both groups, the difference of metastasis-free survival between two groups was not statistically significant (P Z 0.653). Both serum TGF-b 1 and IL-8 levels between two groups were not significantly different (P > 0.05). However, in the entire group, patients developing grade 2 or worse acute skin toxicity had higher serum levels of IL-8 at the 4 week after the start of radiation therapy compared to those with grade 1 skin toxicity only (P Z 0.008). Conclusions: The sequence of adjuvant anastrozole with post-operative radiation therapy did not seem to impact the acute radiation-induced toxicity, nor did it appear to influence the therapeutic outcomes with early follow-up. Neither serum TGF-b 1 nor IL-8 level in the course of radiation therapy was influenced by the sequence of anastrozole with radiation therapy. Higher lever of serum IL-8 in the course of radiation therapy might be associated with more severe acute radiation-induced skin toxicity. Further follow-up is needed to identify the impact of serum IL-8 on late radiation toxicity. Author Disclosure: Q. Zhang: None. X. Yu: None. X. Mei: None. L. Cao: None. X. Guo: None. J. Chen: None.