ESTRO 2021 Abstract Book

S1037

ESTRO 2021

Planned

for

rectal

surgery

and and

15

metastasectomy chemotherapy

after

SCRT

No. (%) rectal primary and all metastases resected

11 (73%)

No. (%) rectal surgery completed

12 (80%)

No. (%) rectal or liver surgery completed

13 (87%)

No. (%) liver surgery completed

10 (77%)

13

No. (%) rectal and liver surgery completed

9 (69%)

13

Time in weeks from first # RT to rectal surgery-mean (range)

24.1 (12- 45.1)

12

Pathological status of patients who underwent rectal surgery

12

Total mesorectal excision

12 (100%)

CRM Margin -ve at surgery

11 (92%)

CRM margin +ve at surgery

1 (8%)

Path CR

1 (8%)

Mandard TRG 1-2

6 (50%)

Reasons for not having rectal surgery as planned

4

Progression of metastatic disease

1 1 1

Operative mortality from liver resection

Chemotherapy related death

Conclusion For this cohort of patients short course radiotherapy is pragmatic, efficient and effective and it results in an excellent pathological response in those who undergo surgery. Whilst it is safe, the treatment paradigm of SCRT, chemotherapy and surgery is not without toxicity and must be used with caution. PO-1259 Increased SII and low Hb level are associated with poor OS in rectal cancer after preoperative CRT Y. Lin 1 1 Changhua Christian Hospital, Radiation Oncology, Changhua City, Taiwan Purpose or Objective For T3/T4N0 or T(any)N+ or locally unresectable rectal cancer, preoperative chemoradiation(CRT) followed by radical resection is the standard of care. Studies have revealed that the hematological inflammatory markers could predict oncological outcomes and chemoradiotherapy responses in rectal cancer patients. The purpose of this study is to evaluate the preoperative hematological parameters affecting overall survival (OS) , as well as the predictive values of the levels of absolute neutrophil count (ANC), neutrophil-lymphocyte ratio (NLR), and systemic immune-inflammation index (SII) on OS. Materials and Methods From January 2010 to December 2018, 98 patients with primary rectal cancer without distant metastases finished preoperative CRT followed by radical surgery at our institution. Patients’ demographic characteristics, clinical and pathological variables, and laboratory data at baseline, during-CCRT and peri- operative were collected by review of medical records. The Cox proportional hazard model and Kaplan-Meier curve analysis were used to assess OS. The receiver operating characteristic (ROC) curve with Youden Index was chosen as thresholds to dichotomize continuous variables. Results The median age was 58 years old , male predominant (72.4%) and most (89.8%) with moderately differentiated histology. All patients completed CRT either with 50Gy in 25 fractions or with 50.4Gy in 28 fractions to whole pelvis and pelvic lymph nodes. 3D-CRT, IMRT, and VMAT were all included. The neoadjuvant chemotherapy regimens included oral UFUR/ Capecitabine (n=72, 73.4%), FL/FOLFOX/FOLFIRI (n=8, 8.2%), CapeOX(n=18, 18.4%). All patients received surgical intervention in 12 weeks after finishing RT. Median follow- up was 50.5 months (range,0–123 months). The 3-year OS was 79.9% for all patients. Univariate analysis showed that preoperative WBC (>5200/μL vs. ≤5200/μL, p = .009), low Hb( p = .004) , peripheral platelet (>217 x10^3/μL vs. ≤217 x10^3/μL, p = .001), increased ANC ( p =.003), increased NLR ( p = .025) and SII(>656 x10^9/L vs. ≤656 x10^9/L, p = .012) were significantly associated with poor OS . The area under the ROC curve for SII (0.695) was larger than those for preoperative ANC(0.674) and preoperative NLR(0.674). On multivariate analysis, preoperative increased SII (Hazard Ratio [HR] 1.001; 95% CI 1.000-1.001, p = .048) and low Hb level (HR 0.735; 95% CI 0.574-0.941, p = .015) remained significantly associated with reduced OS.