Abstract Book

S197

ESTRO 37

Conclusion Low-dose RT is an appropriate treatment for orbital MALT lymphoma in terms of high disease control and acceptable morbidity. Proper lens shielding provided the low incidence of cataract. OC-0386 Incidence of pneumonitis and CKD following novel FP IMRT TBI conditioning for full intensity HSCT. E. Durie 1 , E. Nicholson 2 , C. Anthias 2 , E. Dunne 1 , M. Potter 2 , M. Ethell 2 , C. Messiou 3 , J. Brennan 2 , S. Eagle 1 , W. Ingram 4 , F. Saran 1 , H. Mandeville 5 1 The Royal Marsden Hospital, Department of Radiotherapy, London, United Kingdom 2 The Royal Marsden Hospital, Haemato-Oncology Unit, London, United Kingdom 3 The Royal Marsden Hospital, Radiology, London, United Kingdom 4 The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, Joint Department of Physics, Sutton, United Kingdom 5 The Royal Marsden Hospital, Department of Radiotherapy & Haemato-Oncology Unit, London, United Kingdom Purpose or Objective Total body irradiation (TBI) remains a key component of conditioning regimes for allogeneic haemopoietic stem cell transplant (HSCT), with radiation-induced interstitial pneumonitis (IP) and chronic kidney disease (CKD) the most significant sequalae. The reported rates of IP post TBI are between 11-31%, with an associated mortality rate of nearly 50%; the rates of renal dysfunction are as high as 44%. We have undertaken a retrospective service evaluation of all patients treated at The Royal Marsden since the introduction of a forward planned intensity modulated radiotherapy technique (FP IMRT) for TBI, assessing the incidence of IP and CKD in patients undergoing full intensity HSCT. Material and Methods 74 adult patients were identified, treated with TBI between July 2009 and February 2016 since the introduction of FP IMRT-based TBI. All received 14.4 Gy in 8 fractions over 4 days, prescribed at 100%; the lungs and kidneys both receiving a reduced mean dose of between 12-12.5 Gy. IP was defined as multilobar infiltrates on CT with symptoms of dyspnoea, and renal dysfunction was defined as an eGFR <60 for >3 months. Results The patients in this series received treatment for the following diagnosis: ALL (n=34); AML (n=32), T-LBL (n=3), CML-BC (2) and CNS relapse of NHL (n=1).The median age at start of TBI was 27.6 years (range 17.0-46.1 yrs). The estimated 4 year overall survival and progression free survival rate was 71% (58%-80%) and 65% (52%-76%) respectively with a median follow up time of survivors of 3.9 years (range 1.2-7.7 yrs). We found the rates of IP due to any cause to be 30% with 16 (73%) of these 22 patients having positive microbiological evidence of infection at that time. The rates of idiopathic IP was 8% (CTCAE Grade ≥1), with only 2 patients suffering with IP of CTCAE grade ≥ 3. The median time after TBI for developing IP was 146 days (range 10-406 days). Seven patients (9.5%) died from chest sepsis a median of 246 days after TBI (range 89- 2413 days). Of the 52 long term survivors only two developed CKD, one of which had biopsy confirming thrombotic microangiopathy. Conclusion This novel FP IMRT based TBI technique, with reduced dose to the lungs and kidneys, has resulted in significantly lower rates of radiation-induced IP and CKD compared to the literature. Idiopathic IP of CTCAE Grade ≥3 was observed in just 2.7% of patients. The rate of long term risk of renal dysfunction is very low, with 1 secondary to thrombotic microangiopathy, which can be

Table 1. Correlation between mean heart dose and respective cardiac substructure 3DCRT IMRT PROTONS

BETA

Rho (R 2 ), %

Rho (R 2 ), %

Rho (R 2 ), %

BETA (Slope)

BETA (Slope)

Structure

(Slope)

AV LA RA

24 0.51 65 0.73 41 0.97 70 1.25 58 0.87 59 1.25 76 1.26 81 1.07

37 0.79 54 0.74 39 0.92 67 1.52 35 0.79 54 1.15 74 1.18 85 1.20

34 1.35 29 1.03 21 0.81 65 2.15 21 0.94 26 0.77 58 0.98 50 1.01

LAD

MV TV LV RV

Conclusion Previously seen relationships between mean heart dose and mean substructure dose change with increasingly conformal techniques. This change in relationships indicate that contouring the cardiac substructures, especially the LAD and LV, is important in understanding the late cardiac risks of RT when using more conformal techniques, especially proton therapy. OC-0385 Patterns of Relapse and Outcomes of Orbital MALT Lymphomas treated with Radiotherapy J. Lee 1 , K.C. Keum 2 , C. Jaeho 2 , Y. Jin Sook 3 , C.O. Suh 2 1 Inha University Hospital, Radiation Oncology, Incheon, Korea Republic of 2 Yonsei university, Radiation Oncology, Seoul, Korea Republic of 3 Yonsei university, Ophthalmology, Seoul, Korea Republic of Purpose or Objective The purpose of this study is to report patterns of relapse and clinical outcome of primary orbital mucosa- associated lymphoid tissue (MALT) lymphomas patients treated with radiation therapy (RT). Material and Methods We reviewed 212 consecutive patients (246 treated eyes) who diagnosed orbital MALT lymphomas and received curative-intent RT between 1993 and 2013. The median age was 46 years. Tumor was involved in conjunctiva (134/246, 54%), eyelid (22/246, 9%), retrobulbar (79/246, 32%), and lacrimal gland (11/246, 5%). Median RT dose was 25.2 Gy in 14 fractions. Conjunctival and eyelid lesions were treated with 6-9 MeV electron, whereas retrobulbar and lacrimal gland lesions with photons. Lens shielding was applied for 71% of treated eyes. Results The median follow-up period was 5.3 years. Complete response was seen in 245 treated orbits (245/246, 99%). Relapse occurred in 29 patients with a median time of 39 months, that were consisted of local (11/212, 5%), contralateral orbit (18/212, 8%), and distant (7/212, 3%). RT was most commonly used as a salvage treatment after relapse (21/29, 72%). The 7-year local relapse, contralateral orbit relapse, and distant relapse rates were 5.8%, 4.6%, and 2.6%, respectively. There were 12 deaths with a median time of 144 months, one due to treatment related mortality with refractory MALT lymphoma and eleven due to intercurrent disease. The 7- year relapse-free survival, overall survival, cause-specific survival rates were 79.4%, 97.9%, and 98.8%, respectively. Regarding chronic toxicity, grade 3 cataracts were observed in 22 (9%) treated orbits with median time of 43 months, grade 3 nasolacrimal duct obstruction in 3 patients, and grade 2 dry eye in 16 patients.