Hallemeier, Christopher L.

864 Background: Definitive chemoradiotherapy (CRT) is the standard of care for localized or locally advanced ACSCC, while surgery is typically reserved for salvage therapy. Outcome of treatment with local excision alone is unknown and is currently not recommended by NCCN. We retrospectively analyzed outcome of the patients with small (T1 lesion) incidentally found ACSCC who were treated with local excision alone. Methods: On retrospective analysis, a cohort of 12 patients with pathologically confirmed stage I ACSCC treated at Mayo Clinic between 1994 and 2014 was identified who were managed with local excision alone. Baseline as well as followup data were obtained by electronic chart review. Results: Median age of the patients at diagnosis was 68 years (range: 36-81 years) and majority were females (76.9%). Median follow-up duration was 7.5 years. Of the 12 patients, 2 patients did not receive standard CRT due to co-morbid conditions and other 10 patients chose surveillance over CRT. There was only one patient with disease recurrence at 3 years which was salvaged by abdominoperineal resection (APR). This subject remains alive and disease free at the time of data collection (4 years out from APR). There were 4 deaths, all unrelated to ACSCC. Of 12 patients, 10 patients (83%) remained disease free at 5 years and beyond, 1 patient had recurrence and 1 patient was lost to follow up at 5 months from diagnosis. Conclusions: Local excision as a single modality of treatment may be safe and effective for highly selected small stage I ACSCC. Further clinical study is warranted to accurately define the patient population who can be treated with local excision alone, potentially sparing them long term toxicities.

AbstractAimShort‐term morbidity and long‐term functional outcome of patients with an ileal pouch‐anal anastomosis (IPAA) exposed to pelvic external beam radiation therapy (EBRT) remains unknown. We report the largest series to date regarding the effects of pelvic EBRT on: (i) 30‐day postoperative outcomes; and (ii) long‐term functional outcome following IPAA.MethodA retrospective chart review was conducted of patients who received EBRT before or after IPAA between 1980 and 2017 across three international inflammatory bowel disease referral centres.ResultsNineteen patients were included. Indications for EBRT were rectal adenocarcinoma (n = 13), prostate adenocarcinoma (n = 4) or anal squamous cell carcinoma (ASCC) (n = 2). EBRT was given prior to IPAA in 12 (63%) patients and after IPAA in seven (37%). In EBRT before IPAA, patients had a median of 5 (range: 4–8) daytime bowel movements, 1 (range: 0–5) night‐time bowel movement, no daytime incontinence, and only one patient used pads at a median follow up of 25 (range: 11–163) months; one patient underwent pouch excision 15 months after IPAA. In EBRT after IPAA, patients reported a median of 8 (range: 5–10) daytime and 2 (range: 0–5) night‐time bowel movements, 80% had either daytime or night‐time incontinence and 80% used pads at a median follow up of 90 (range: 25–315) months.ConclusionPelvic EBRT administered prior to IPAA is associated with acceptable long‐term function outcome. However, when pelvic EBRT is given to an IPAA in situ, most patients experience poor long‐term pouch function without pouch failure.

3556 Background: To define and update survival rates and relapse patterns in patients (pts) with isolated advanced abdominal nodal metastasis secondary to colorectal cancer (CRC), treated with curative intent using aggressive trimodality therapy. Methods: Fifty-seven pts with isolated advanced abdominal lymph node metastasis (retroperitoneal and mesenteric) secondary to colorectal cancer received trimodality therapy defined as chemotherapy delivered in conjunction with external beam radiotherapy (EBRT) followed by lymphadenectomy and intraoperative radiotherapy (IORT). Infusional 5-FU was the most common radiosensitizer used (66%, 38 pts). The median dose of EBRT was 50 Gy & the median dose of intraoperative radiotherapy was 12.5 Gy. End points included distant metastasis, toxicities, local failure within EBRT field, recurrence within the intraoperative radiotherapy field, and survival. Results: 49% of pts were male, median age 50.5 yrs. All patients had ECOG ≤ 1. 27 pts had primary right sided colon cancer, 16 left sided colon cancer and 14 rectal primaries. Median time from initial CRC diagnosis to development of abdominal lymph node metastatic disease was 24 months (95% CI, 23.5-45.1 months). 84% (48 pts) had paraaortic nodal metastases, 12% (7 pts) had mesenteric nodal metastases, and 3% (2 pts) had both. With a median follow up of 89.4 months, the median overall survival and 5-year estimated survival rate were 53.2 months (95% CI, 46.4-78.8 months) and 42%, respectively. Median progression free survival was 19.3 months (95% CI, 15.6-32.8 months). 21 (37%) pts never developed distant disease. Outcome was not affected by disease sidedness, rectal primary, or mutational profile. Treatment was well tolerated without any grade 3/4 toxicities. Conclusions: The use of trimodality therapy including EBRT with radiosensitizing chemotherapy, lymphadenectomy and IORT produces sustainable long-term survival in selected metastatic CRC pts presenting with isolated retroperitoneal/mesenteric nodal relapse.

Abstract Background and study aims Little consideration has been given to selection of endoscopic ultrasound-guided fiducials for proton radiotherapy and the resulting perturbations in the therapy dose and pattern. Our aim was to assess the impact of perturbations caused by six fiducials of different composition and dimensions in a phantom gel model. Materials and methods The phantom was submerged in a water bath and irradiated with a uniform 10 cm × 10 cm field of 119.7 MeV monoenergetic spot scanning protons delivered through a 45 mm range shifter. The proton “Bragg Peak” was evaluated. Results Dose perturbations manifesting as dose reductions up to 30 % were observed. A carbon composite (1 × 5 mm) and gold (0.4 × 10 mm) fiducial with backload potential rather than dedicated EUS pre-loaded gold fiducial needles had the best performance in terms of minimizing the dose perturbation. Conclusions Our data demonstrate that a carbon composite fiducial has a less untoward effect on proton therapy dose distribution than dedicated EUS pre-loaded gold fiducial needles. Such information is important to consider when selecting fiducials specifically for proton therapy.

Abstract Background The purpose of this study was to define survival rates in patients with isolated advanced abdominal nodal metastases secondary to colorectal cancer (CRC), treated with curative-intent trimodality therapy. Materials and Methods Sixty-five patients received trimodality therapy, defined as chemotherapy delivered with external beam radiotherapy (EBRT) followed by lymphadenectomy and intraoperative radiotherapy (IORT). Infusional 5-fluorouracil was the most common radiosensitizer used (63%, 41 patients). The median dose of EBRT was 50 Gy, and the median dose of IORT was 12.5 Gy. We evaluated time to distant metastasis, toxicities, local failure within the EBRT field, recurrence within the IORT field, and survival. Results Fifty-two percent of patients were male; patients’ median age was 50.5 years. All patients had an Eastern Cooperative Oncology Group score ≤1. Twenty-nine patients had right-sided colon cancer, 22 had left-sided colon cancer, and 14 had rectal primaries. The median time from initial CRC diagnosis to development of abdominal nodal metastatic disease was 20.6 months (95% confidence interval [CI], 21.2–40.8 months). Seventy-eight percent (51 patients) had para-aortic nodal metastases, 15% (10 patients) had mesenteric nodal metastases, and 6% (4 patients) had both. With a median follow-up of 77.6 months, the median overall survival and 5-year estimated survival rate were 55.4 months (95% CI, 47.2–80.9 months) and 45%, respectively. The median progression-free survival was 19.3 months (95% CI, 16.5–32.8 months). Twenty-six (40%) patients never developed distant disease. The outcome was not affected by disease sidedness or rectal primary. Treatment was well tolerated without grade 3 or 4 toxicities. Conclusion Trimodality therapy produces sustainable long-term survival in selected patients with metastatic CRC presenting with isolated retroperitoneal or mesenteric nodal relapse. Implications for Practice This article reports a unique trimodality approach incorporating external beam radiotherapy with radiosensitizing chemotherapy, surgical resection, and intraoperative radiotherapy provides durable survival benefit with significant curative potential for patients with metastatic colorectal cancer who present with isolated abdominal nodal (mesenteric and/or retroperitoneal) recurrence.

Objective: To determine the impact of histology on pathologic response, survival outcomes, and recurrence patterns in patients with esophageal cancer (EC) who received neoadjuvant chemoradiotherapy (CRT). Summary of Background Data: There is a paucity of data regarding comparative outcomes after neoadjuvant CRT between esophageal squamous cell carcinoma (SCC) and adenocarcinoma. Methods: Between 2002 and 2015, 895 EC patients who underwent neoadjuvant CRT followed by esophagectomy at 3 academic institutions were retrospectively reviewed, including 207 patients with SCC (23.1%) and 688 patients with adenocarcinoma (76.9%). Pathologic response, survival, recurrence pattern, and potential prognostic factors were compared. Results: Pathologic complete response (pCR) rate was significantly higher for SCC compared with adenocarcinoma (44.9% vs 25.9%, P < 0.001). After a median follow-up of 52.9 months, 71 patients (34.3%) with SCC versus 297 patients (43.2%) with adenocarcinoma had recurrent disease (P = 0.023). For patients who achieved a pCR, no significant differences were found in recurrence pattern, sites, or survival end-points between the 2 histology groups. For non-pCR patients, the SCC group demonstrated significantly higher regional and supraclavicular recurrence rates but a lower hematogenous metastasis rate than adenocarcinoma patients, whereas the adenocarcinoma patients had a more favorable locoregional failure-free survival (P = 0.005) and worse distant metastasis-free survival (P = 0.024). No differences were found in overall survival (P = 0.772) or recurrence-free survival (P = 0.696) between groups. Conclusions: SCC was associated with a significantly higher pCR rate than adenocarcinoma. Recurrence pattern and survival outcomes were significantly different between the 2 histology subtypes in non-pCR patients.

Objective: To discern recurrence risk stratification and investigate its influence on postoperative surveillance in patients with esophageal adenocarcinoma (EAC) after neoadjuvant chemoradiotherapy (CRT). Background: Reports documenting recurrence risk stratification in EAC after neoadjuvant CRT are scarce. Methods: Between 1998 and 2014, 601 patients with EAC who underwent neoadjuvant CRT followed by esophagectomy were included for analysis. The pattern, site, timing, and frequency of the first recurrence and potential prognostic factors for developing recurrences were analyzed. This cohort was used as the training set to propose a recurrence risk stratification system, and the stratification was further validated in another cohort of 172 patients. Results: A total of 150 patients (25.0%) achieved pathologic complete response (pCR) after neoadjuvant CRT and the rest were defined as the non-pCR group (n = 451) in the training cohort. After a median follow-up of 63.6 months, the pCR group demonstrated a significantly lower locoregional (4.7% vs 19.1%) and distant recurrence rate (22.0% vs.44.6%) than the non-pCR group (P < 0.001). Based on independent prognostic factors, patients were stratified into 4 recurrence risk categories: pCR with clinical stage I/II, pCR with clinical stage III, non-pCR with pN0, and non-pCR with pN+, with corresponding 5-year recurrence-free survival rates of 88.7%, 65.8%, 55.3%, and 33.0%, respectively (P < 0.001). The risk stratification was reproducible in the validation cohort. Conclusions: We proposed a recurrence risk stratification system for EAC patients based on pathologic response and pretreatment clinical stage. Risk-based postoperative surveillance strategies could be developed for different risk categories.