Abstract Book

ESTRO 37

S378

Patients (37 cases) showing higher tumour repopulation (Ki67 above the median: 14%) had lower local control figures than slowly proliferating tumours (40 cases) (62% vs. 84.6% at 15 years; p=0,028). Severe late toxicity was modest, especially with treatment delivered by modern Hyperfractionated-accelerated radiotherapy is an effective and safe therapeutic alternative for those patients with locally advanced breast cancer unresponsive to neoadjuvant systemic therapy. Tumour repopulation estimated by Ki67 and total dose administered are the most important factors predicting local control. PO-0739 Role of ki67, tumor size and lymph nodal status as a prognostic index in breast cancer. F. Arcadipane 1 , S. Osella-Abate 2 , A. Vella 1 , P. Franco 1 , S. Martini 1 , G. Iorio 1 , N. Rondi 3 , S. Bartoncini 3 , P. Rovea 3 , I. Castellano 2 , U. Ricardi 1 1 University of Turin- A.O.U. Citta' della Salute e della Scienza, Department of Oncology- Division of Radiation Oncology, Torino, Italy 2 University of Turin- A.O.U. Citta' della Salute e della Scienza, Department of Medical Sciences- Division of Pathology, Torino, Italy 3 A.O.U. Citta' della Salute e della Scienza, Department of Oncology- Division of Radiation Oncology, Torino, Italy Purpose or Objective Breast cancer (BC) is a heterogeneous disease, with different subtypes having distinct biological features with peculiar patterns of response to treatment and various clinical outcomes. The intent of this analysis was to validate a prognostic index based on Ki67 expression, tumor size and number of metastatic lymph nodes in a large cohort of patients affected with BC and treated with different post-operative radiotherapy (RT) approach. Material and Methods A retrospective analysis was conducted on 770 patients affected with Luminal A and Luminal B, estrogen receptor positive and HER2 negative BC who underwent surgery and RT between 1994 and 2012. Data were analyzed with respect to the type of surgery and RT to test the correlation between the prognostic index and loco- regional recurrence rate, disease free interval (DFI) and disease-specific survival (DSS). Results Patients characteristics are shown in Table 1. Breast- conserving surgery (BCS) was performed in 711, while 59 underwent mastectomy. In BCS group, 329 patients received conventionally RT and 382 hypofractionated RT. Boost dose to tumor bed was given to 515 patients. After mastectomy, patients received standard RT on the chest wall and, in 40 cases, nodal irradiation. Analyzing outcomes of BCS versus mastectomy group, 10-year DFI and DSS were 86.7% vs 67.7% and 96.5% vs 80.3%, respectively. (Fig.1, A-B) The prognostic index was used by assigning a score for each feature and analyzing the cohort by dividing it into two groups: score <3(681 patients) and score≥ 3 (89 patients). PROGNOSTIC INDEX SCORE TUMOR SIZE techniques. Conclusion

Conclusion To our knowledge, this is the first study evaluating hippocampal involvement in PCNSL. Despite multifocal and/or bilateral disease at presentation, sparing of one or both hippocampi may be possible in up to 77% of patients. Future studies should therefore evaluate hippocampal sparing WBRT and its the impact on neurocognitive function and should explore clinico- pathological and molecular predictors of patterns of relapse in PCNSL.

Poster: Clinical track: Breast

PO-0738 Hyperfractionated-accelerated radiotherapy in locally advanced breast cancer: Fifteen-year results R. Carmona-Vigo 1 , L.A. Henríquez Hernández 1 , B. Pinar Sedeño 1 , M. Lloret Sáez-Bravo 1 , P.C. Lara Jiménez 1 1 Las Palmas de Gran Canaria, Radiation Oncology, Las Palmas de Gran Canaria, Spain Purpose or Objective To evaluate the role of high dose radiotherapy in local control of the disease by hyperfractionated-accelerated scheme in those patients resistant to neoadjuvant systemic therapy. Tumour repopulation during radiotherapy could influence clinical outcomes. Material and Methods One hundred-eighty four patients were included in this prospective study from 1991-2011. Whole breast was treated to a dose of 60 Gy, 1.2 Gy/fraction, two fractions/day, followed by a boost of 21.6 Gy to a total dose of 81.6 Gy in seven weeks. Tumour repopulation was estimated in pre-treatment biopsies by Ki67 immunostaining. Both clinical response and toxicity were evaluated during follow-up, closed in December 2013. Results 177 patients were evaluated for response with a mean follow-up of 132 months. The local relapse-free survival at 5, 10 and 15 years was 85.6, 82.2 and 82.2%, respectively, while the overall survival was 52.8, 34.5 and 23.3%, respectively. The radiation dose received was a determining factor for local control of the disease.

≤ 15 mm 0 >15 mm 1

0 1 2 0 1

N of METASTATIC LYMPH NODES 0

1-3 4-9 <20

Ki67

≥ 20