Comparing the RTOG/EORTC and LENT-SOMA scoring systems for the evaluation of late skin toxicity after I seed brachytherapy for parotid gland cancer.

Purpose: The Radiation Therapy Oncology Group (RTOG) and Late Effects Normal Tissue Task Force-Subjective, Objective, Management and Analytic (LENT-SOMA) scoring systems were compared for grading late skin effects after iodine-125 seed brachytherapy in parotid gland cancer patients.

Methods And Materials: A total of 109 patients diagnosed with parotid gland carcinoma were treated postoperatively with iodine-125 seed brachytherapy at a dose of 100-120 Gy. After 6-24 months of followup, telangiectasia, skin pigmentation, atrophy, fibrosis, and ulceration were scored according to both RTOG and LENT-SOMA scale criteria. The strength of correlation between the scores and the interobserver variability were calculated.

Results: Of 109 patients, 22.9% had telangiectasia; 78.9%, pigmentation; 28.4%, fibrosis; 4.6%, edema; 0.9%, ulceration; 37.6%, retraction and/or atrophy; 22.9%, sensation change; and 11%, scaliness and/or roughness. Compared with RTOG, LENT-SOMA criteria resulted in the upgrading of pigmentation in 17% of cases, the downgrading of all instances of telangiectasia and the downgrading of one instance of Grade 4 ulceration to Grade 3. Between the two scales, fibrosis and atrophy correlated well (Spearman ρ, 0.992, 0.986). An additional 229 side effects were observed using LENT-SOMA criteria.

Conclusions: The LENT-SOMA scale was more accurate than the RTOG scale for the evaluation of late skin and subcutaneous toxicity. The downgrading of telangiectasia and upgrading of pigmentation with the LENT-SOMA scale reflected the patients' conditions better than the scores obtained with the RTOG scale. The assessment of fibrosis and atrophy correlated well between the two scales. The use of the sum of the individual scores of the LENT-SOMA is therefore advocated. The addition of decreased sweating and the removal of the alopecia (scalp) metric should be considered to standardize the reporting of late radiation morbidity.