ESTRO 36 Abstract Book

S43 ESTRO 36 _______________________________________________________________________________________________

into this study. We excluded patients with relapse after previous radiotherapy/brachytherapy or follow-up < 12 months. 5-year relapse free survival was estimated. Cox regression model was used to find any factors associated with local control. Results Ninety eight patients (56 females/42 males) were analyzed in this retrospective study. Median age was 72 years (45-91). 112 primary and 43 post surgery lesions to total of 167 were treated with surface brachytherapy. Median of lesions’ greatest dimension was 2 cm (0.2-8). Median total dose was 45 Gy (30-50 Gy) with dose per fraction of 5 Gy. Dose was specified 0.3-0.5 cm from the surface of the applicator. Median follow-up was 54 months (12-95). 5-year local relapse-free survival was 94%. Single factor linked to local failure was lesion localization in the concha and/or external acoustic meatus (HR-2.6; 1.4-3.8; Surface HDR brachytherapy is very effective for the treatment of basal cell caner. Lesions localized in the concha/external acoustic meatus should be managed carefully. OC-0084 Results of excision and 13 Gy single dose HDR brachytherapy for keloids C. Hafkamp 1 , O. Lapid 2 , R. Dávila Fajardo 1 , A. Van de Kar 2 , C. Koedooder 1 , L. Stalpers 1 , B. Pieters 1 1 Academic Medical Center P.O. Box, Radiation Oncology, Amsterdam, The Netherlands 2 Academic Medical Center P.O. Box, Plastic and Reconstructive Surgery, Amsterdam, The Netherlands Purpose or Objective To investigate the outcome of a single dose of 13 Gy HDR given postoperatively for the treatment of keloids. Surgical treatment of keloids results in high recurrence rates of 50-80%. Therefore surgical resection is often combined with radiotherapy. We report the result in terms of both local control and cosmesis. Material and Methods Between 2007 and 2015, 61 patients were treated for 72 keloids. All patients were contacted to participate. All patients had a surgical excision followed by 13 Gy HDr brachytherapy within 4 hours. Usually a single catheter was placed in the wound bed with dose prescribed at 4-7 mm from the source axis. In some cases a volume implant was applied according to the Paris-system geometry and dosimetry or the dose was prescribed at dose points on the skin. A recurrence was defined as an elevation of the scar outside the initial wound. Cosmetic assessment was according to the Patient and Observer Scar Assessment Scale (POSAS). The POSAS score can range from 6-60, higher scores correspond with worse scarring. Results Twenty-four patients (39%) with 29 keloids consented to participate in the study. The median age at treatment was 31 years (15 – 64 years). The median follow-up period was 53 months, (19 – 95 months). The most frequent localization was the ear (n=14). Recurrence was reported for 7 (24.1%) out of 29 keloids. Two recurrences were localized presternally, two on one ear, one in the neck, one abdominal and one on the shoulder. Patients scored on average 24.3 for their total POSAS score (range 6 – 52) and the observer scored on average 14.6 (range 6 – 42) (Figure 1). Patients scored stiffness as the most bothersome side effect followed by thickness. The observer gave the highest score to overall impression followed by surface area. p-0.0000). Conclusion

Conclusion Compared to favorable reports in the literature, typically reporting about 10% recurrence rates, we found a high recurrence rate of 24% following excision and brachytherapy for keloids. This may be explained by our much longer follow-up of at least 1.5 years, and a more stringent and objective definition of response by the POSAS patient and observer reported outcome. Our results may have been further negatively biased by selection; despite repeated invitations, the willingness to participate was very low, partly explained by the poorer socio-economic background of the patients. Publication bias may also have deterred publication of less favorable results, and stresses the need of prospective multicenter trials with a uniform scoring system. OC-0085 In search for the optimal HDR brachytherapy radiation scheme after excision in keloid treatment. E. Bijlard 1 , G.M. Verduijn 2 , J.X. Harmeling 1 , H. Dehnad 3 , M.A.M. Mureau 1 1 Erasmus Medical Center Rotterdam Daniel den Hoed Cancer Center, Plastic Surgery, Rotterdam, The Netherlands 2 Erasmus Medical Center Rotterdam Daniel den Hoed Cancer Center, Radiation Oncology, Rotterdam, The Netherlands 3 University Medical Center Utrecht, Radiation oncology, Utrecht, The Netherlands Purpose or Objective Keloids are benign lesions that can cause physical symptoms and disturbing appearance. Excision with radiation is considered the most effective treatment option for recurrent keloids. Previously a BED of 30Gy was reported as the minimal effective dose to prevent keloid recurrence, this was based mainly on external radiation (EBRT) studies. In a recent review high dose rate (HDR) brachytherapy achieves favorable outcome over EBRT. The included studies used different radiation schemes. The optimal scheme for HDR brachytherapy in keloid treatment preventing recurrences and treatment side effects needs to be determined. Material and Methods We retrospectively collected patient and keloid characteristics, information on complications, and (partial or full) keloid recurrence of all patients who received excision with HDR brachytherapy in center 1 from 2010 to May 2014 and in center 2 from 2009 to 2014. In case follow-up was insufficient or information was missing, telephone interviews were performed. Center 1 used 9 Gy 2 hours postoperatively and 9 Gy 6 hours later. Center 2 used 6 Gy six hours postoperatively, followed by additional 2x6 Gy a day later. Center 3 has recently published a prospective cohort, in detail, using 6 Gy 4 hours postoperatively and 6 Gy the next day. We compared results of all 3 centers. All centers used an Ir192 HDR

source. Results

Comparing the 3 centers no significant differences were found in recurrence rates (full recurrence 9.3%, 3.1%, 8.6% p=0.31, no recurrence 79%, 77%, 91% p=0.169 for center 1,