ESTRO 2020 Abstract Book

S85 ESTRO 2020

Material and Methods Data about patients treated with concomitant IT or TT and RS were retrospectively collected. Concurrent time was considered a period of 4 weeks. L-PFS and D-PFS were defined as the time from RS to local progression of the treated lesions and to the appearance of new BM, respectively. Patients should have at least a follow up of 3 months. Safety results were reported according to the CTCAE v4.1. Kaplan Meyer analysis of survival was performed. Results Data of 254 NSCLC patients from 19 Italian radiotherapy centers were analyzed. Patients were treated from 05/01/2007 to 29/11/2018. Median age was 65 years (range 33-86). A total of 499 BM were treated: 184 (72%) patients were treated in a single fraction while 70 (28%) with Hypo-Fractionated radiotherapy. The most used drugs were Nivolumab (22%), Pembrolizumab (16%), Erlotinib (15%), Gefitinib (13%) and Crizotinib (12%). Patients and treatments characteristics are summarized in Table 1. Eleven patients were lost during follow up (FUP). After a median FUP of 7 months L-PFS, D-PFS and OS were 48 months (range 30m-69m), 12 months (range 9m-16m) and 7 months (range 2m-15m) respectively. Nivolumab compared to Pembrolizumab seemed to show a better L- PFS (HR: 0.7 CI 95%: 0.14-3.04), D-PFS (HR 0.79 CI 95% 0.35-1.77) and OS (HR: 0.5 CI 95% 0.2-1.7) without reaching a statistical significance. Among TT Erlotinb compared to Gefitinb and Crizotinib showed a better OS while D-PFS showed a trend in favor of Gefitinib. Grade 2 and 3 Radionecrosis were reported in 10 (4%) and 2 (1%) patients, respectively. No other severe neurological toxicity were described.

Poster discussion: CL: Breast 1

PD-0176 Survival After Breast-Conserving Therapy Compared With Mastectomy in Stage I-IIA Breast Cancer I. Ratosa 1 , G. Plavc 1 , T. Zagar 2 1 Institute of Oncology Ljubljana, Department of Radiation Oncology, Ljubljana, Slovenia ; 2 Institute of Oncology Ljubljana, Department of Epidemiology and Cancer Registry, Ljubljana, Slovenia Purpose or Objective Large retrospective population-based studies of early- stage breast cancer (BC) suggest that breast-conserving therapy (BCT) is at least equivalent or even better in terms of BC-specific and overall survival (OS) compared to mastectomy. In this study, we compared BCT consisting of breast conserving surgery (BCS) and radiotherapy to mastectomy-only in stage I-IIA BC. Material and Methods The study cohort consisted of all stage I-IIA (T1/2N0 or T0/1N1) BC patients diagnosed in 2013 and treated with BCT or mastectomy-only, achieving clear margins, and with a known surrogate definition of intrinsic subtype of BC (Luminal A-like, Luminal B-like HER2-negative, Luminal B-like HER2-positive, HER2-positive and triple negative BC). Differences between patients treated with BCT and those treated with mastectomy were compared using the chi-squared test, 5-year overall (OS) and disease-free survival (DFS) were estimated using Kaplan-Meier method and multivariate Cox proportional hazards models were conducted to estimate hazard ratios (HRs) for OS and DFS. Results Of the 568 patients included in the study, 421 (74.1%) received BCT and 147 (25.9%) mastectomy. Compared to BCT, mastectomy group had more patients younger than 45 years (17.7% vs. 8.8%, p=0.003), higher Charlson comorbidity index score (CCI) (p<0.001), more patients had multicentric BC (65.3% vs. 26.8%, p<0.001) and more patients had axillary lymph node dissection (20.4% vs. 12.3%, p<0.001). However, no significant differences were observed between patients treated with BCT vs. those with mastectomy in the distribution of overall stage, intrinsic subtype, receipt of endocrine therapy, chemotherapy, or targeted (anti-HER2) therapy. Median follow-up was 55.2 months. Two (0.4%), 1 (0.2%) and 14 (2.5%) patients experienced local, regional and distant relapse, respectively, and 24 (4.2%) patients died. Kaplan-Meier estimated 5-year DFS was 95.4% in BCT (95% confidence intervals (CI) 93.4–97.4) and 88.7% (95% CI 83.2–94.2) in mastectomy group (p=0.014). Estimated 5-year OS was 96.9% (95% CI 95.3–98.5) in BCT group compared to 91.8% (95% CI 87.1–96.5) in mastectomy group (p=0.024). In adjusted analysis accounting for age, CCI, multicentricity, overall stage, intrinsic subtype, type of primary local treatment and receipt of chemotherapy, only younger age was significantly associated with improved 5-year OS. However, in adjusted analysis accounting for the same confounding factors, receipt of BCT had a significantly positive effect on DFS compared with mastectomy (HR 0.42; 95% CI 0.19–0.91; p=0.027).

Patient's Characteristics

Number 254 (%)

Gender MF

140

(55%)114

(45%)

Age MedianRange

65

years33-86

years

Smoke

(p/y)

Unknown 0 <10 10-20>20

164

(64.5%) (5.5%)

14

8

(3%)

6 (2%)62 (25%)

Histology Adenocarcinoma

Squamous

Cell

232 (91%)22 (9%)

Carcinoma Molecular

Biology

EGFR+ ALK+PDl-1> 1%

77 (30%) 41 (16%)53 (21%)

Stage

at

diagnosis

Unknown M0 M1Brain M1 0-1 1.5-2 2.5-33.5-4 molGPA

5

(2%)

94 (37%) 155 (61%)72 (28%)

Score

17

(7%)

105 (41%) 109 (43%)23 (9%)

Conclusion Our data suggest that RS and IT or TT for the treatment of BM from NSCLC is feasible and safe. Among IT Nivolumab seems to be associated with a better intracranial control and OS compared to Pembrolizumab, while there is not a clear difference in terms of outcomes between different targeted agents. Prospective data are needed to confirm our results.