Abstract Book

S808

ESTRO 37

Conclusion IMRT-SIB with total dose of 55 Gy (2,2 Gy/fr) is feasible, with tolerable acute and late toxicity and no increase in surgical morbidity. Early results showed good outcome in terms of pathological complete response and T- downstaging as compared to conventional treatment. Long-term follow-up is needed to evaluate local control and survival. EP-1489 Outcome after neoadjuvant chemoradiation in elderly patients (≥ 70 years) with rectal cancer F. Roeder 1 , M. Dantes 1 , R. Isleiwa 1 , S. Gerum 1 , A. Jensen 1 , C. Belka 1 1 University Hospital LMU Munich, Radiation Oncology, Munich, Germany Purpose or Objective To analyze the outcome of elderly patients with rectal cancer after neoadjuvant chemoradiation. Material and Methods 76 patients (m/f 58:18) aged ≥70 years with UICC stage II/III rectal adenocarcinoma treated with neoadjuvant chemoradiation in curative intent at our institution between 2003 and 2015 were retrospectively analyzed. Median age was 75 yrs (70-86). Staging included endoscopy with biopsy in all and MRI and/or endorectal ultrasound in 75%. 47% were located in the lower third, 96% had T3/4 and 63% were node positive. All pts received 5-FU based neoadjuvant chemoradiation (Capecitabine or 5-FU c.i. througout RT or 2 cycles of 5- FU week 1,5; 3DCRT 93%, IMRT 7%) with a median dose of 50,4 Gy (45-59,4 Gy). Adjuvant CHT was given to 28 patients. Toxicity was evaluated according to CTCAE 4.0. Univariate subgroup analyses were performed with log rank or fisher test. Results Median f/u was 48 months (2-167). Radiation treatment could be completed without major breaks in 95% and 83% of the pts received ≥80% of the scheduled CHT. Maximum acute toxicity was grade 1 in 29%, grade 2 in 47%, grade 3 in 21% and grade 4 in 3%, mainly hematological and gastrointestinal. 69 pts (91%) underwent surgery, while 7 did not (distant failure 3, refused 2, toxicity 1, death of unknown cause 1). Of the 69 resected pts, 53 received TAR and 16 APR. Margins were R0 in 91%, R1 in 3% and Rx in 6%. Severe postoperative complications (Clavien-Dindo 3b-4b) were observed in 13 pts (19%). Postoperative 30- day mortality was 0%. 8 pts achieved pCR (12%) and 42 (61%) showed downstaging. Local failure in resected pts was observed in 6 (10%) translating into a 5-year LC rate of 90%. LC was significantly associated with resection margin, quality of TME (Mercury) and grade. Distant metastases were found in 22 pts (29%) resulting in a 5- year DC rate of 69%. Distant failure was significantly influenced by pN stage, resection margin, type of CHT (Cap/c.i. vs cycles) and achievement of LC. 5-year FFTF rate was 66%. FFTF was significantly associated with pN stage, pUICC stage, downstaging, resection margin and type of CHT. 5-year OS in resected pts was 64%. Performance status, grade, compliance to simultaneous CHT and application of adjuvant CHT had significant impact on survival. Regarding the entire cohort we found a 5-year OS rate of 58%, which was strongly associated with surgery (5-year OS 64% vs 0%) and performance status (KPS ≥/<80%) prior to treatment initiation (5-year OS 75% vs 43%). Conclusion Neoadjuvant 5-FU based chemoradiation is feasible with acceptable toxicity in elderly patients with rectal

adenocarcinoma and results in a similar outcome compared to younger cohorts. OS is strongly associated with surgery and performance status. Contineous CHT applications should be preferred. EP-1490 Radiotherapy for the primary tumor in metastatic rectal cancer B. Polat 1 , I. Feuerbach 1 , A. Kerscher 2 , A. Wiegering 3 , M. Flentje 1 1 University hospital Würzburg, Department of Radiation Oncology, Würzburg, Germany 2 University hospital Würzburg, Comprehensive Cancer Center Mainfranken, Würzburg, Germany 3 University hospital Würzburg, Department of General- Visceral- Vascular and Pedatric Surgery, Würzburg, Germany Purpose or Objective In primary metastatic rectal cancer there is no clear guideline on how to integrate local treatment of the primary cancer to systemic treatment and how to sequence multimodal therapy. Here, we analyzed if local radiotherapy of the primary cancer had an impact on patient outcome. Material and Methods From 2000 to 2015 a total of 107 rectal cancer patients with synchronous metastatic disease were included in this retrospective analysis. All patients received either a combination of chemotherapy, surgery (metastatic site or primary tumor) or radiotherapy. Of these, 40 patients received long-term radio-(chemo)therapy and 12 had short course radiation. Kaplan-Meier analysis using log- rank statistics were used for comparing overall survival. Results Median patient age was 62.0 years. Thirty one patients were female and 76 were male. Median follow-up was 31.0 months. Local tumor stage was T2 3%, T3 75% and T4 22%. Metastases were localized at following organs: liver 74, lung 9, combined lung + liver 15 and other sites 9 patients. Solitary liver metastases were seen in 20 patients and multiple metastases within one organ were seen in 61 patients. Treatment was initiated with systemic chemotherapy in 26%, local radiotherapy in 35% or with a surgical approach in 39%. Overall survival for the total group was 23.0 months. The addition of local treatment of the rectum resulted in an overall survival of 20.2 vs 12.8 months for surgery vs no surgery (p=0.01). Radiotherapy alone added no benefit to overall survival (7.9 vs 12.8 months, n.s.). But when radiotherapy was used in addition to surgery, overall survival increased to 42.0 vs 20.2 months (p=0.007). A local approach to the metastatic site was also associated with a survival improvement (39.2 vs 13.8 months, p<0.01). We could not give a clear recommendation on which treatment approach represents the optimal sequence. Conclusion Multimodal treatment in primary metastatic rectal cancer leads to an overall survival benefit. Adding radiotherapy to surgery of the primary tumor increased overall survival time. These observations need to be tested in a prospective trial. EP-1491 Neoadjuvant chemoradiotherapy in rectal cancer patients in a 15-year single institutional experience C. ROSA 1 , M. Di Tommaso 1 , L. Caravatta 1 , M. Taraborrelli 1 , A. Augurio 1 , S. Di Biase 1 , I.A. Zecca 2 , M. Di Nicola 2 , D. Genovesi 1 1 SS. Annunziata Hospital- “G. D’Annunzio” University,