ESTRO 38 Abstract book

S229 ESTRO 38

kikuchi level, budding, pT2, R1. CXB was performed with the Papillon50 tm machine and dose was 40 to 60 Gy in 2 or 3 fractions (depending on association with EBRT) over 2 to 4 weeks. Kaplan Meier estimates was used for outcomes measures. Results Median age was: 70 years. Male:127, Female :70. cN0: 189, cN1: 8 (4%). pT staging was : pT1: 146, pT2: 46, pT3: 5 . CXB alone was given in 27 pts and combined with EBRT in 170 (EBRT alone(45 -50 Gy/ 5 weeks):35, chemoRT :107, EBRT “short course”: 28 pts. Median follow-up time was 41 months. Local relapse rate at 5 years was 8% and distant metastases 11%. Organ preservation was achieved in 95% with good bowel function in nearly all patients. Main toxicity was rectal bleeding due to radiation mucosal telangiectasia. Due to small number of events only few prognostic parameters were observed: LVI for local relapse (4% vs 19% out of 63 pts with LVI reported ) and sm3 vs sm1-2 for distant metastases (DM). A local relapse was associated with a higher risk of DM (5% vs 44%, p< 0.0001) Conclusion This appears to be the largest ever presented multicenter cohort study using adjuvant CXB for early rectal cancer with pejorative features after local excision. This strategy brings high rate of local control and rectal preservation with good bowel function. It appears to be a good option for well-informed patients to avoid safely the risks of a radical TME after LE. OC-0436 13 SCC penis treated with HDR brachytherapy, results and dosimetric analysis M. Marban Orejas 1 , J. Crook 1 , M. Keyes 2 , D. Batchelar 1 , R. Dubash 2 , F. Bachand 1 1 BCCA, Radiation Oncology, Kelowna BC, Canada ; 2 BCCA, Radiation Oncology, Vancouver BC, Canada Purpose or Objective We report a retrospective analysis of treatment features and results for 13 localized penile SCC treated with HDR brachytherapy (BT) Material and Methods 6 patients (T1a-b) received plesiotherapy and 7 (T1-2) interstitial BT. CTV was defined as GTV+5mm, or 3mm below the skin after excisional biopsy (n=2). Skin refers to a 2mm rind on the penis within the applicator and urethra is a central 1cm circle or the catheter contoured on CT. We performed a descriptive analysis to correlate dosimetry with clinical outcomes Results HDR mold BT was used for 5 T1a tumors and 1 T1b(G3 pN0) between 11/15-02/17. Median age was 68(51-78) 40Gy/10 was prescribed BID 6hours apart. Median CTV was 4.4cc(2.6-11.8) Median dosimetric parameters were CTV V100 80.3%, V125 0.2%; skinD5 118%(125-107); urethral Dmax 102%(118-75), D5 95% and D30 89%. Median follow up is 29.3months(20-35). All patients are alive and free of disease(NED). 1 patient had a local failure at 17months presenting as a non-healing ulcer and urethral stricture. He had a partial penectomy for pT3 recurrence, and remains NED 15months later. No other urethral or soft tissue toxicity occurred. First 2patients treated have G2 telangiectasias on the shaft(image1), proximal to treated site, attributed to redundant penile skin sliding into treatment volume. Subsequently, a Lucite applicator allowed visual position check and a constriction ring at the penile base immobilized the skin(image3). All sexually active patients remain potent.

HDR interstitial BT was used for 7patients between11/09- 05/18. Median age was 51.7(33-77). 2patients had T1 and 5 had T2 disease. 2 underwent inguinal LND, one for G3(pN0) and one cN1(pN2) Dose prescribed was 42Gy/12 in 3patients while the other 4 received 42/14, 45/12, 53/17 and 38.4/12, BID 6h apart.

Table1 summarizes dosimetric parameters

Median follow up is 98 months(5-106). All patients are alive and NED at last follow up, 5 with intact penis, and 3 remain potent 1patient failed locally at 21months with a non-healing ulcer unresponsive to hyperbaric oxygen. 6 years after partial penectomy and pelvic/groin dissection(pN1), he is alive and NED. The first 4 patients had G2necrosis, 3 received hyperbaric oxygen. The implant had catheter spacing >12mm(14-17mm) and unacceptable inhomogeneity (V150mean 47%, V125mean 85%). For the final 2patients, catheter spacing 9-12mm was used and V150 limited to<20%,V125 to~45% 1 patient presented with G1 meatal stenosis, 1 with urethral stenosis requiring dilatations(G2) and 1 perineal urethrostomy(G3). There was no correlation between toxicity and implant geometry in those cases, but BED, considering urethral α/ß=3, was higher(101.2 and 108.2Gy), and they had diabetes. Conclusion HDR brachytherapy is effective treatment for SCC penis either as a surface mold or interstitial. Homogeneity parameters should be followed. There may be a correlation between urethral BED and complications. A constriction ring is advisable in mold treatment to avoid skin toxicity More prospective analyses are warranted