(P 205) PREOPERATIVE CHEMORADIATION (MODIFIED EILBER PROTOCOL) VERSUS NEOADJUVANT/ ADJUVANT RADIOTHERAPY FOR SOFT TISSUE EXTREMITY SARCOMAS: A POPULATION BASED ANALYSIS IN ALBERTA

Objective: The primary objectives of this study were to compare the local recurrence rates and long term outcomes (disease free and overall survival) of extremity soft tissue sarcomas (STS) among patients treated with modified Eilber protocol, versus those treated with neoadjuvant and adjuvant radiation (RT) within the province of Alberta. Secondly, we sought to identify any factors associated with local recurrence of STS, as well as, factors associated with STS mortality.

Methods: The study was a retrospective multi-centre cross-sectional survey in the province of Alberta, Canada which spanned a period of 12 years (2004-2016). Data was collected from the Cancer Alberta database for all eligible patients (patients who underwent treatment of curative intent with either Modified Eilber protocol, neoadjuvant or adjuvant radiotherapy for STS) within the above-mentioned timeframe. Data variables collected included demographic variables such as age and sex, as well as, variables related to diagnosis and treatment, for example: date of diagnosis, tumour location, grade and size; date of surgery; type of treatment received and recurrence (local and distant). Descriptive statistics were computed and specific statistical tests used to evaluate for correlations among select variables and local recurrence, as well as, death.

Results: Charts were reviewed for 260 patients who met the inclusion criteria for the study. Of these patients 56.2% were males and the mean age was 56.1(±17.2) years (95% CI: 53.97 to 58.18). The most common tumour location was the proximal lower limb (45.4%). The majority of sarcomas fell into the category of other (43.5%) with the single most common histology noted being that of undifferentiated pleomorphic sarcoma for persons who received modified Eilber (29.4%) and neoadjuvant RT (17.9%). Overall, most tumours were grade 3 (51.9%), between 6cm to 10cm in size (41.5%) and were deep to the fascia (79.6%). A total of 39.2% patients underwent treatment with the modified Eilber protocol versus 36.6% neoadjuvant RT, 20 % adjuvant RT and 4.2% no RT. Local recurrence was 11.8% for the modified Eilber group, 8.4% in the neoadjuvant RT group and 9.6% in the adjuvant RT group with p values all > 0.05 (range 0.73-0.99). The median follow-up years or until death was found to be 4.91 years (Range: 0 to 12.5 years). The 30-day mortality rate was 0.8%. The only factor that was found to be clearly significantly associated with local recurrence was margin status (p < 0.005). While those associated with death were determined to be sex (p =0.01) and age at diagnosis (p < 0.005).

Conclusion: This study demonstrated that the use of the Modified Eilber protocol at our institution has equivalent oncologic outcomes when compared to neoadjuvant and adjuvant RT. This protocol has the benefits of achieving these outcomes but with lower radiation doses, and favourable wound complication rate as previously shown by Mack et al. OS and DFS at 5 years were 65.7% +/- 3.1 (95%CI: 59.3% to 71.4%) and 57.9% +/- 3.2 (95% CI: 51.3% to 64.0%) respectively.