ESTRO 38 Abstract book

S812 ESTRO 38

trimester presented with a deep vein thrombosis and found to have a right pelvic mass biopsy of which confirmed a SCC. She was treated with chemotherapy, external beam radiotherapy and a single dose of intra- cavitary brachytherapy. Case#3 A 40-year-old lady with a history of pelvic pain was diagnosed with p16 positive SCC after MRI showed a large infiltrative mass. She was treated with external beam radiotherapy with concomitant chemotherapy. We present treatment outcomes on all three patients and a review of the available literature. Conclusion Our case series highlights the complexities involved in the management of these rare CUP of the pelvis. Our three cases add to the very small number of previously reported cases in the literature to date. Identification of a primary site is important since therapy is potentially curative. We cannot deduce whether HPV/p16 caused these cancers but it may be that the HPV status can be helpful in identifying mucosal sites. It may thus prove a useful tool in developing a diagnostic and treatment paradigm for such patients. EP-1501 Prognostic value of SCC-Antigen and SUVmax value in locally advanced cervix cancer S. Pedraza Fernández 1 , P. Sarandeses 2 , D. Lora 3 , J.F. Pérez-Regadera 1 1 Hospital Universitario 12 de Octubre, Radiation Oncology, Madrid, Spain ; 2 Hospital Universitario 12 de Octubre, Nuclear Medicine, Madrid, Spain ; 3 Hospital Universitario 12 de Octubre, CIBER de Epidemiología y Salud Pública imas12-CIBERESP, Madrid, Spain Purpose or Objective The aim of this study is to combine tumour SUVmax (maximum standardized uptake) value at diagnosis and pretreatment squamous cell carcinoma antigen (SSC-Ag) level to evaluate the impact of both in predicting the response to combined chemoradiotherapy (CCRT) in locally-advanced cervix cancer (LACC). Material and Methods From March 2009 to October 2015, 114 consecutives patients (pts.) with LACC who underwent a 18F-FDG- PET/CT at diagnosis were enrolled in this retrospective study. Pts. were staged according to FIGO 2008 system. All received definitive radiotherapy in combination with weekly Cisplatin and endocavitary brachytherapy. A follow-up time, in the absence of an event, higher than 2 years(yrs) was required. Univariate analysis was performed studying independently the differences in SCC-Ag group and tumor-SUVmax value group and clinic prognostic variables. Kruskal-Wallis test was used; p value

included. Among them, 149 patients received EBRT (external beam radiation therapy) after radical hysterectomy, 64 received EBRT combined with intracavitary brachytherapy. There was no statistical difference in FIGO stage and pathological type distribution between the two groups. A dose of 45-50.4Gy in 25-28 fractions was prescribed to the planning target volume with IMRT. Those who underwent brachytherapy were supplemented with 18-30Gy/3-5Fx. Survival analyses were performed using Kaplan-Meier method, and Cox model was used to analyze prognostic factors. Results The median follow-up was 52 months (9-136 months), and 3 years PFS was 77%. Among them, 62 patients had local or distant recurrence, 31 cases in pelvic (including vaginal cuff), 10 cases with metastases to para-aortic or inguinal lymph nodes, and 21 cases with distant metastasis. The types of pathology, large mass, positive lymph node, FIGO stage and depth of invasion were all highly significantly and independently related to risk of recurrences (P=0.004, 0.023, 0.013, 0.003 and 0.035, respectively). However, the adjuvant chemotherapy was not a significant factor influenced PFS (P=0.88), which did not reduce the risk of pelvic relapse or distant metastasis (P=0.27, P=0.40). We found that when the patients received EBRT with dose of 45Gy, 1) if the invasive depth reaching or exceeding the deep muscle layer, the brachytherapy could significantly reduce the recurrence(P = 0.049); 2) if the tumor size was more 4cm, the brachytherapy could reduce the recurrence (mean PFS, 58.83±9.28 months vs. 35.33±6.78 months), though the difference was not statistically significant (P=0.20). Conclusion The pathology, stage, mass, lymph node status and depth of invasion were the prognosis factors of cervical cancer patients with radical hysterectomy in our study. Preliminary results showed that adjuvant chemotherapy did not improve the prognosis of these patients. In those who received prescribed dose of 45Gy for the EBRT, high risk factors such as depth of invasion and large tumor size would be the key factors for the case selection to additional intracavitary therapy. And more data is needed for further research. EP-1500 Squamous Cell Carcinoma of unknown primary (CUP) in the Pelvis:A case series and review of literature E. Connolly 1 , G. Rangaswamy 1 , O. Boychek 1 , C. Gillham 1 , O. McArdle 1 1 St Luke's Radiation Oncology Center, Radiation Oncology, Dublin, Ireland Purpose or Objective The diagnosis and management of Carcinoma of unknown primary (CUP) represents a challenge. Of the 3–5% of invasive cancers that are classified as CUP approximately 5%–10% are squamous cell carcinomas (SCCs), many of which are HPV +ve and are commonly located in the head and neck. HPV +ve SCCs CUP in the pelvis are extremely rare and there is not much known about the aetiology, pathogenesis, or ideal radiation therapy target coverage. Material and Methods Electronic medical records and patient charts registered as SCC CUP between 2014 and 2018 inclusive were reviewed. Those with a diagnosis of CUP in the Pelvis were included in our study. We also conducted a literature review to identify published data reporting treatment outcomes. Results Three patients with CUP in the Pelvis were identified at our institution. Case#1: A 62-year-old lady presented with a three-month history of progressive lower back pain. Imaging revealed a left pelvic sidewall mass, confirmed as p16 positive SCC. She was treated with chemo- radiotherapy. Case#2: A 33-year-old lady, in her first