Neoadjuvant Short-course Radiotherapy Research Articles

Delayed Surgery after Neoadjuvant Short-course Radiation for Rectal Cancer Improves Pathologic Outcomes without Impacting Survival: A National Cancer Database Analysis.

Interval to surgery following short course radiotherapy (SCRT) for rectal cancer is not standardized. This study investigated pathologic outcomes and survival with varying intervals to surgery. Using the National Cancer Database, adults who received SCRT from 2005 to 2020 were grouped by additional neoadjuvant chemotherapy. Outcomes were analyzed for early (within 1 week) and delayed (over 4 weeks) intervals. Of 1154 patients, 671 received neoadjuvant SCRT and chemotherapy (Group 1: median interval 29 days, 50% delayed) and 483 received SCRT only (Group 2: median interval 9 days, 27% delayed). In Group 1, delay was associated with tumor downstaging (OR 1.61; 95% CI, 1.03-2.51; p = 0.036), decreased lymphovascular invasion (OR 0.53; 95% CI, 0.33-0.85; p = 0.009), and complete pathologic response (OR 2.86; 95% CI, 1.06-7.76; p = 0.039). Delay was associated with decreased tumor deposits in Group 1 (OR 0.46; 95% CI, 0.30-0.71; p < 0.001) and Group 2 (OR 0.37; 95% CI 0.21-0.65; p = 0.001). Survival was not affected. Delaying surgery following neoadjuvant SCRT results in favorable pathologic outcomes without impacting overall survival, regardless of neoadjuvant chemotherapy.

Short-Course TNT Improves Rectal Tumor Downstaging in a Retrospective Study of the US Rectal Cancer Consortium.

The RAPIDO trial showed promising rates of pathologic complete response (pCR) after neoadjuvant short-course radiation with consolidation chemotherapy (total neoadjuvant therapy [SC TNT]) for rectal cancer. Only single-center reviews comparing tumor downstaging between SC TNT and long-course chemoradiation (LCRT) have been published in the United States. We reviewed our multi-institutional experience with both. The US Rectal Cancer Consortium database (2007-2018) including data from six high-volume rectal cancer care centers was reviewed. Patients with nonmetastatic, rectal adenocarcinoma who had neoadjuvant LCRT alone or SC TNT before excision or definitive nonoperative management were included. The primary outcome was the rate of complete response (CR), including pCR or durable (12 month) clinical complete response. Of 857 included patients, 175 (20%) received SC TNT and 682 (80%) received LCRT. The LCRT group had more low tumors (51.8% vs. 37.1%, p < 0.0001) and more clinically node-negative disease (31.8% vs. 22.3%, p < 0.0001). The CR rate was higher after SC TNT (34.1% vs. 20.3%, p = 0.0001). SC TNT was a predictor of CR (OR: 2.52, CI: 1.68-3.78). SC TNT patients completing 5-6 months of consolidation chemotherapy had a CR rate of 42.9%. There was no difference in 3-year PFS. SC TNT increases CR rate when compared to LCRT. For patients seeking nonoperative options or fewer radiation treatments, SC TRT should be preferred over LCRT alone.

Early Outcomes of Preoperative Short Course Radiotherapy With Simultaneous Integrated Boost and Response-adapted Chemotherapy for Advanced Rectal Cancer

Background and purposeLimited evidence exists for dose escalation in neoadjuvant short course radiotherapy (SCRT) for rectal cancer. With enhanced imaging and radiotherapy techniques over the past decades along with the valuable endpoint of pathological complete response (pCR), we believe SCRT with simultaneous integrated boost could potentially provide deeper pathological responses and improve local control. Methods and MaterialsBetween January 2020 and December 2022, locoregional-advanced rectal cancer patients that were treated with neoadjuvant SCRT with simultaneous integrated boost up to 5.5–6Gy per fraction with five daily fractions followed by response-adapted chemotherapy was retrospectively reviewed. The pCR rates, R0 resection rates, tumor downstaging, toxicities, and early pattern of recurrence are reported. ResultsAmong the 76 patients, 67 (88%) were able to undergo curative intent surgery. R0 resection was achieved in 99% (n = 66) of patients with pCR rates of 28% (n = 19). Forty-six percent (n = 31) of patients had significant pathological downstaging (ypT2N0) and 55% (n = 37) of patients had both T and N downstaging. Most common grade 3 or above radiotherapy-related side-effects were proctitis, rectal pain, and dermatitis found in 5% (n = 4), 3% (n = 2) and 3% (n = 2) of patients, respectively. Grade 3 or above surgical complications were observed in 15% (n = 10) of patients. There were no treatment-related deaths. With a median follow-up of 27 months, only 6% (n = 4) had local recurrence after surgery. ConclusionsNeoadjuvant short course radiotherapy with simultaneous boost for rectal cancer is feasible with no added toxicities. Patients who underwent surgery achieve a high R0 resection and pCR rates. Early data suggest low rates of locoregional recurrence. Further follow-up and research is needed to validate and optimize the dose, method, and schedule of dose escalation.

Predicting Pathologic Complete Response in Locally Advanced Rectal Cancer with [68Ga]Ga-FAPI-04 PET, [18F]FDG PET, and Contrast-Enhanced MRI: Lesion-to-Lesion Comparison with Pathology.

Neoadjuvant therapy in patients with locally advanced rectal cancer (LARC) has achieved good pathologic complete response (pCR) rates, potentially eliminating the need for surgical intervention. This study investigated preoperative methods for predicting pCR after neoadjuvant short-course radiotherapy (SCRT) combined with immunochemotherapy. Methods: Treatment-naïve patients with histologically confirmed LARC were enrolled from February 2023 to July 2023. Before surgery, the patients received neoadjuvant SCRT followed by 2 cycles of capecitabine and oxaliplatin plus camrelizumab. 68Ga-labeled fibroblast activation protein inhibitor ([68Ga]Ga-FAPI-04) PET/MRI, [18F]FDG PET/CT, and contrast-enhanced MRI were performed before treatment initiation and before surgery in each patient. PET and MRI features and the size and number of lesions were also collected from each scan. Each parameter's sensitivity, specificity, and diagnostic cutoff were derived via receiver-operating-characteristic curve analysis. Results: Twenty eligible patients (13 men, 7 women; mean age, 60.2 y) were enrolled and completed the entire trial, and all patients had proficient mismatch repair or microsatellite-stable LARC. A postoperative pCR was achieved in 9 patients (45.0%). In the visual evaluation, both [68Ga]Ga-FAPI-04 PET/MRI and [18F]FDG PET/CT were limited to forecasting pCR. Contrast-enhanced MRI had a low sensitivity of 55.56% to predict pCR. In the quantitative evaluation, [68Ga]Ga-FAPI-04 change in SULpeak percentage, where SULpeak is SUVpeak standardized by lean body mass, had the largest area under the curve (0.929) with high specificity (sensitivity, 77.78%; specificity, 100.0%; cutoff, 63.92%). Conclusion: [68Ga]Ga-FAPI-04 PET/MRI is a promising imaging modality for predicting pCR after SCRT combined with immunochemotherapy. The SULpeak decrease exceeding 63.92% may provide valuable guidance in selecting patients who can forgo surgery after neoadjuvant therapy.

Neoadjuvant short-course radiotherapy followed by camrelizumab and chemotherapy in locally advanced rectal cancer (UNION): early outcomes of a multicenter randomized phase III trial

Neoadjuvant short-course radiotherapy (SCRT) followed by CAPOX and camrelizumab (a programmed cell death protein 1 monoclonal antibody) has shown potential clinical activity for locally advanced rectal cancer (LARC) in a phase II trial. This study aimed to further confirm the efficacy and safety of SCRT followed by CAPOX and camrelizumab compared to long-course chemoradiotherapy (LCRT) followed by CAPOX alone as neoadjuvant treatment for LARC. In this randomized, phase III trial, patients with T3-4/N+ rectal adenocarcinoma were randomly assigned (1 : 1) to receive SCRT or long-course chemoradiotherapy (LCRT), followed by two cycles of camrelizumab and CAPOX or CAPOX alone, respectively. After surgery, each arm underwent either six cycles of camrelizumab and CAPOX, followed by up to 17 doses of camrelizumab, or six cycles of CAPOX. The primary endpoint was pathological complete response (pCR) rate (ypT0N0) assessed by a blinded independent review committee. Key secondary endpoints tested hierarchically were 3-year event-free survival (EFS) rate and overall survival (OS). Between July 2021 and March 2023, the intention-to-treat population comprised 113 patients in the experimental arm and 118 patients in the control arm, with surgery carried out in 92% and 83.9%, respectively. At data cut-off (11 July 2023), the pCR rates were 39.8% [95% confidence interval (CI) 30.7% to 49.5%] in the experimental arm compared to 15.3% (95% CI 9.3% to 23.0%) in the control arm (difference, 24.6%; odds ratio, 3.7; 95% CI 2.0-6.9; P < 0.001). In each arm, surgical complication rates were 40.0% and 40.8%, and grade ≥3 treatment-related adverse events were 29.2% and 27.2%. Three-year EFS rate and OS continue to mature. In LARC patients, neoadjuvant SCRT followed by camrelizumab plus CAPOX demonstrated a significantly higher pCR rate than LCRT followed by CAPOX, with a well-tolerated safety profile. SCRT followed by camrelizumab and chemotherapy can be recommended as a neoadjuvant treatment modality for these patients.

Phase II study of neoadjuvant short-course radiotherapy combined with CAPEOX plus envafolimab in patients with microsatellite stable locally advanced rectal cancer: Updated results of PRECAM study.

3614 Background: Conventional neoadjuvant chemoradiotherapy (nCRT) yields a pathologic complete response (pCR) rate of about 15%–- 30% for locally advanced rectal cancer (LARC). This PRECAM study aimed to investigate the efficacy and safety of neoadjuvant short-course radiotherapy combined with CAPEOX plus Envafolimab in Patients with Microsatellite Stable (MSS) LARC, redefining the standard of care (SOC) for LARC. Methods: The study is an open-label, prospective, single-arm, phase II clinical study . Eligible patients with MSS LARC were consecutively enrolled. Participants received short-course radiotherapy (25Gy/5f) with subsequent two cycles of CAPEOX (capecitabine and oxaliplatin) and 6 cycles of Envafolimab (subcutaneous injection, 150 mg, QW ) followed by total mesorectal excision surgery. The primary endpoint was pathological complete response (pCR) rate, and the secondary endpoint was major pathologic (MPR) rate and safety. Results: From April to December 2022, 34 patients were enrolled, of whom 32 completed the study. Remarkably, The pCR rate was62.5% (20/32), and the (MPR) rate was 75% (24/32). Furthermore, 65.6% (21/32) patients achieved a neoadjuvant rectal (NAR) score below 8, suggesting an effective treatment response. Common adverse events included tenesmus (78.1%), diarrhea (62.5%), and leukocyte decrease (40.6%), with two cases of Grade 3 adverse events. Surgical procedures were performed in all 32 cases, with minor complications observed. During the follow-up period of up to 20 months, no recurrence or death were reported. Conclusions: Short-course radiotherapy combined with CAPEOX plus Envafolimab showed favorable pCR rate with manageable adverse effects and surgical complications in LARC, underscoring the potential of the combination therapy for MSS LARC. A Randomized controlled trial is warranted for further exploration and validation. Clinical trial information: NCT05216653 .

Three-year survival data from a phase 2 trial of neoadjuvant short-course radiotherapy followed by chemotherapy and camrelizumab in locally advanced rectal cancer.

e15611 Background: For locally advanced rectal cancer (LARC), short-course radiotherapy (SCRT) or long-course chemoradiotherapy combined with chemotherapy have been the established neoadjuvant treatment, but the optimal therapeutic modality is still under exploration. We previously reported the short-term results of neoadjuvant SCRT followed by chemotherapy and camrelizumab (a PD-1 inhibitor), encouragingly noting pathological complete response (pCR) in 48.1% of LARC patients (Lin Z et al. J Immunother Cancer 2021;9:e003554). Here, we report the further 3-year follow-up results. Methods: Adult patients with histologically confirmed T3-4N0M0 or T1-4N+M0 rectal adenocarcinoma were enrolled. Prior to surgery, eligible patients received 5×5 Gy SCRT, and after one week, they were treated with camrelizumab (200 mg, i.v., on day 1) plus CAPOX chemotherapy (oxaliplatin 130 mg/m2, i.v., on day 1 and capecitabine 1000 mg/m2, orally, bid, on days 1-14) in 21-day cycles for 2 cycles. Radical surgery was performed one week after the last neoadjuvant cycle. For this updated analysis, disease-free survival (DFS) and overall survival (OS) at 3 years are reported. Results: Thirty patients were enrolled and received SCRT, and all of these patients were included in this OS analysis. Among them, 27 patients received camrelizumab plus CAPOX chemotherapy, all of whom underwent surgery and were included in this DFS analysis. Of the 27 patients, 21 patients (77.8%) received at least one cycle of postoperative adjuvant chemotherapy with CAPOX regimen. With a median follow-up of 40.8 months (IQR 40.3-44.3), disease recurrence or death occurred in six (22.2%) patients. The median DFS and OS were both not reached, with the 3-year DFS and OS rates of 80.2% (95% CI 58.6-91.3) and 93.3% (95% CI 75.9-98.3), respectively. Subgroup analysis showed that patients with pCR, postoperative pathological node-negative status, PD-L1 combined positive score ≥ 1, and negative circumferential resection margin and negative extramural venous invasion by MRI at baseline had a tendency towards improved 3-year DFS and OS compared to those without these characteristics. No new or long-term safety signals were identified. Conclusions: With 3 years of extended follow-up, a favorable survival benefit was observed with neoadjuvant SCRT combined with subsequent CAPOX plus camrelizumab followed by delayed surgery in LARC patients. A randomized phase 3 trial (NCT04928807) is ongoing to confirm these results. Clinical trial information: NCT04231552 .

Role of neoadjuvant rectal score in prognosis and adjuvant chemotherapy decision-making in locally advanced rectal cancer following neoadjuvant short-course radiotherapy and consolidation chemotherapy

Objectives: To assess the prognostic impact of the neoadjuvant rectal (NAR) score following neoadjuvant short-course radiotherapy and consolidation chemotherapy in locally advanced rectal cancer (LARC), as well as its value in guiding decisions for adjuvant chemotherapy. Methods: Between August 2015 and August 2018, patients were eligible from the STELLAR phase III trial (NCT02533271) who received short-course radiotherapy plus consolidation chemotherapy and for whom the NAR score could be calculated. Based on the NAR score, patients were categorized into low (＜8), intermediate (8-16), and high (＞16) groups. The Kaplan-Meier method, log rank tests, and multivariate Cox proportional hazard regression models were used to evaluate the impact of the NAR score on disease-free survival (DFS). Results: Out of the 232 patients, 24.1%, 48.7%, and 27.2% had low (56 cases), intermediate (113 cases), and high NAR scores (63 cases), respectively. The median follow-up period was 37 months, with 3-year DFS rates of 87.3%, 68.3%, and 53.4% (P＜0.001) for the low, intermediate, and high NAR score groups. Multivariate analysis demonstrated that the NAR score (intermediate NAR score: HR, 3.10, 95% CI, 1.30-7.37, P=0.011; high NAR scores: HR=5.44, 95% CI, 2.26-13.09, P＜0.001), resection status (HR, 3.00, 95% CI, 1.64-5.52, P＜0.001), and adjuvant chemotherapy (HR, 3.25, 95% CI, 2.01-5.27, P＜0.001) were independent prognostic factors for DFS. In patients with R0 resection, the 3-year DFS rates were 97.8% and 78.0% for those with low and intermediate NAR scores who received adjuvant chemotherapy, significantly higher than the 43.2% and 50.6% for those who did not (P＜0.001, P=0.002). There was no significant difference in the 3-year DFS rate (54.2% vs 53.3%, P=0.214) among high NAR score patients, regardless of adjuvant chemotherapy. Conclusions: The NAR score is a robust prognostic indicator in LARC following neoadjuvant short-course radiotherapy and consolidation chemotherapy, with potential implications for subsequent decisions regarding adjuvant chemotherapy. These findings warrant further validation in studies with larger sample sizes.

Abstract CT130: Epacadostat with preoperative chemoradiation in locally advanced rectal cancer (LARC): Results of a translational phase I clinical trial

Abstract BACKGROUND: In preclinical studies, we found that the immuno-oncology target and tryptophan metabolizing enzyme indoleamine 2, 3-dioxygenase 1 (IDO1) promotes resistance to radiation in rectal cancer regardless of MSI status. Furthermore, IDO1 inhibition with epacadostat improved tumor radiosensitivity, abrogated immunosuppression, limited distal recurrence, and was radioprotective of the normal intestine. This trial aimed to evaluate the safety of IDO1 inhibition when combined with neoadjuvant short-course radiation (SCRT) and chemotherapy with capecitabine and oxaliplatin (CAPOX) for LARC. METHODS: The primary objective was to determine the recommended phase II dose (RP2D) of epacadostat for combination with SCRT and CAPOX. Secondary objectives included determining antitumor activity as measured by neoadjuvant rectal (NAR) score and pathological or clinical complete responses. During the dose escalation phase, 3 doses of epacadostat (300mg, 400mg, &amp; 600mg BID) were explored. Epacadostat was combined with SCRT (5Gy x 5 fractions) followed by 6 cycles of CAPOX chemotherapy, until the day of surgery (~24 wks). Tissues and blood were collected for correlative studies. A control cohort was generated from patients receiving the same treatment without epacadostat. NCT03516708 RESULTS: Seventeen patients were enrolled from 4/2019 to 8/2023. RP2D of epacadostat in combination with SCRT and CAPOX chemotherapy was determined to be 400mg BID. Two patients experienced dose-limiting toxicities (DLT) at 600mg dose level, one with G2 elevated ALT and another with G3 maculopapular rash. No DLT was reported at other dose levels. Of six patients who underwent surgery, the mean NAR score was 7.46 (SD 7.11; range 0 - 20.4), indicating potentially better response compared to the mean NAR of 17.8 in an institutional 2:1 matched control cohort (p=0.03). Tumor tissue revealed increased IDO1 expression and kynurenine levels in all patient tumors after radiation. After epacadostat, serum levels of kynurenine were reduced while TNFα, IFNγ, and MIP1a were all increased. Global metabolomics and RNAseq revealed a distinct pattern of serum biomarkers and immunophenotype respectively in patients after treatment. Tumoroids were evaluated as ex vivo models of treatment response. CONCLUSION: Epacadostat in combination with SCRT and CAPOX was well-tolerated. An NCI supported Phase 2 trial is ongoing to further evaluate the promising disease responses reported in dose escalation phase. Citation Format: Haeseong Park, Katrina Pedersen, Katherine Huang, Matthew Mutch, Hyun Kim, Nikolaos Trikalinos, Olivia Aranha, Benjamin Tan, Rama Suresh, Lee Ratner, Moh'd Khushman, John Visconti, Kian-Huat Lim, Lauren Henke, Maddie Swiecicki, Jingxia Liu, Parag Parikh, Matthew Ciorba. Epacadostat with preoperative chemoradiation in locally advanced rectal cancer (LARC): Results of a translational phase I clinical trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT130.

Study protocol of short-course radiotherapy combined with CAPOX and PD-1 inhibitor for locally advanced colon cancer: a randomised, prospective, multicentre, phase II trial (TORCH-C)

IntroductionThe preliminary result of the TORCH trial has shown a promising complete response (CR) for managing locally advanced rectal cancer with neoadjuvant short-course radiotherapy (SCRT) combined with chemotherapy and PD-1...

Neoadjuvant short-course radiotherapy or chemoradiation plus consolidative chemotherapy followed by radical operation for locally advanced rectal cancer.

Limited evidence compares short-course radiotherapy (SCRT) and long-course chemoradiotherapy (LCCRT), both of which are followed by consolidative chemotherapy before radical rectal surgery. We conducted a retrospective cohort study to assess treatment response, survival outcomes, and toxicity in patients with locally advanced rectal cancer. Patients (cT3-4 and/or N+) treated with SCRT or LCCRT, consolidative chemotherapy, or total mesorectal excision between 2013 and 2021 were identified. the cause-specific cumulative incidence of disease-related treatment failure, locoregional recurrence, distant metastases, and overall survival were evaluated using flexible parametric competing risk analysis and Kaplan-Meier methods, adjusted for treatment regimens and clinicopathological factors. A pathological complete response (pCR), tumor downstaging, and toxicity have been reported. Among the 144 patients, 115 (80%) underwent curative rectal surgery. The LCCRT and SCRT groups achieved pCR in 10 (18%) and seven (12%) patients, respectively (odds ratio, 1.68; 95% confidence interval [CI], 0.59-4.78). The adjusted cause-specific hazard ratio for disease-related treatment failure with LCCRT versus SCRT was 0.26 (95% CI, 0.08-0.87). Three-year cumulative probability of disease-related treatment failure was 10.0% and 25.6% for LCCRT and SCRT, respectively. No significant differences in T-downstaging, N-downstaging, significant pathologic downstaging (ypT0-2N0), locoregional failure, distant metastasis, or overall survival were found. Late rectal toxicity occurred in 10 (15%) LCCRT and two (3%) SCRT patients, respectively. LCCRT with consolidative chemotherapy demonstrated improved disease-related treatment failure compared with SCRT, despite higher late rectal toxicity. Further research is needed to assess the long-term oncologic outcomes and toxicity.

Real-world data on the pattern of recurrence of colorectal cancer at a tertiary cancer center in South India: A retrospective observational study

Background: Recurrent colorectal cancer may be amenable to curative treatment. As the debate on the ideal set of investigations and frequency of follow-up continues, it is important to review the pattern of recurrence in the real-world setting, which could help tailor future follow-up strategies. Objectives: Our primary objective was to study the varying clinical presentations and patterns of recurrence of colorectal cancer. The secondary objectives were to study the site of recurrence, method of diagnosis of recurrence, incidence of second primary colorectal cancer, and salvage rates after recurrence of colorectal cancer. Material and Methods: We reviewed the data of patients who were treated from January 2010 to December 2016 at the Malabar Cancer Center, a tertiary cancer center in Kerala, India. We recorded the clinicopathologic details of patients who were treated with curative intent and had serologic (carcinoembryonic antigen [CEA] elevation), clinical, or radiological evidence of disease recurrence. We also studied the timing and anatomical location of recurrence, symptoms, and the method by which the recurrence was diagnosed. Results: We included 675 patients in the study. There were 324 (48%) female patients; the median age was 55 years (interquartile range [IQR], 47.2-65). The primary diagnosis was colon cancer in 326 (48.3%) and rectal in 349 (51.7%) patients. Multimodality therapy was administered to 393 (58.2%) patients in the form of surgery with or adjuvant neoadjuvant chemoradiation adjuvant radiation, or neoadjuvant short-course radiation with neoadjuvant and adjuvant chemotherapy. Recurrences occurred in 109 (16.1%) patients, only 50 (45.9%) of whom were symptomatic. Recurrences were diagnosed by CEA elevation in 65 (59.6%), imaging in 12 (11%), clinical examination in 4 (3.7%), and colonoscopy in 1 (0.9%) patient. The median time to recurrence was 17 months (95% CI, 14-22). Local and distant recurrences occurred in 29 (4.2%) and 80 (11.9%) patients, respectively; 22 (27.5%) patients developed multisite distant recurrences. Recurrences occurred within the first 5 years of completion of therapy in 96 (88.1%) cases. Twelve (11%) patients received salvage therapy with curative intent. Six patients (0.9%) had a metachronous colorectal primary tumors. Conclusions: Colorectal cancer recurs most commonly in the first 5 years after therapy. Multisite distant recurrence and isolated liver metastases predominate. Recurrences are often asymptomatic and most commonly manifest as elevated CEA. Regular clinical evaluation, CEA testing, colonoscopy, and symptom-based cross-sectional imaging detect up to three-quarters of patients with recurrences, but the overall salvageability remains low.

Abandonment of Routine Radiotherapy for Nonlocally Advanced Rectal Cancer and Oncological Outcomes

Neoadjuvant short-course radiotherapy was routinely applied for nonlocally advanced rectal cancer (cT1-3N0-1M0 with >1 mm distance to the mesorectal fascia) in the Netherlands following the Dutch total mesorectal excision trial. This policy has shifted toward selective application after guideline revision in 2014. To determine the association of decreased use of neoadjuvant radiotherapy with cancer-related outcomes and overall survival at a national level. This multicenter, population-based, nationwide cross-sectional cohort study analyzed Dutch patients with rectal cancer who were treated in 2011 with a 4-year follow-up. A similar study was performed in 2021, analyzing all patients that were surgically treated in 2016. From these cohorts, all patients with cT1-3N0-1M0 rectal cancer and radiologically unthreatened mesorectal fascia were included in the current study. The data of the 2011 cohort were collected between May and October 2015, and the data of the 2016 cohort were collected between October 2020 and November 2021. The data were analyzed between May and October 2022. The main outcomes were 4-year local recurrence and overall survival rates. Among the 2011 and 2016 cohorts, 1199 (mean [SD] age, 68 [11] years; 430 women [36%]) of 2095 patients (57.2%) and 1576 (mean [SD] age, 68 [10] years; 547 women [35%]) of 3057 patients (51.6%) had cT1-3N0-1M0 rectal cancer and were included, with proportions of neoadjuvant radiotherapy of 87% (2011) and 37% (2016). Four-year local recurrence rates were 5.8% and 5.5%, respectively (P = .99). Compared with the 2011 cohort, 4-year overall survival was significantly higher in the 2016 cohort (79.6% vs 86.4%; P < .001), with lower non-cancer-related mortality (13.8% vs 6.3%; P < .001). The results of this cross-sectional study suggest that an absolute 50% reduction in radiotherapy use for nonlocally advanced rectal cancer did not compromise cancer-related outcomes at a national level. Optimizing clinical staging and surgery following the Dutch total mesorectal excision trial has potentially enabled safe deintensification of treatment.

Evaluation and Correlation of Radiological and Pathological Response Following Neoadjuvant Short-course Radiotherapy Followed by Chemotherapy Followed by Surgery in Resectable Locally Advanced Adenocarcinoma of the Rectum

Evaluation and Correlation of Radiological and Pathological Response Following Neoadjuvant Short-course Radiotherapy Followed by Chemotherapy Followed by Surgery in Resectable Locally Advanced Adenocarcinoma of the Rectum

Short-course radiation with consolidation chemotherapy does not increase operative morbidity compared to long-course chemoradiation: A retrospective study of the US rectal cancer consortium.

Neoadjuvant short-course radiation and consolidation chemotherapy (SC TNT) remains less widely used for rectal cancer in the United States than long-course chemoradiation (LCRT). SC TNT may improve compliance and downstaging; however, a longer radiation-to-surgery interval may worsen pelvic fibrosis and morbidity with total mesorectal excision (TME). A single, US-center retrospective analysis has shown comparable risk of morbidity after neoadjuvant short-course radiation with consolidation chemotherapy (SC TNT) and long-course chemoradiation (LCRT). Validation by a multi-institutional study is needed. The US Rectal Cancer Consortium database (2010-2018) was retrospectively reviewed for patients with nonmetastatic, rectal adenocarcinoma treated with neoadjuvant LCRT or SC TNT before TME. The primary endpoint was severe postoperative morbidity. Cohorts were compared by univariate analysis. Multivariable logistic regression modeled the odds of severe complication. Of 788 included patients, 151 (19%) received SC TNT and 637 (81%) LCRT. The SC TNT group had fewer distal tumors (33.8% vs. 50.2%, p < 0.0001) and more clinical node-positive disease (74.2% vs. 47.6%, p < 0.0001). The intraoperative complication rate was similar (SC TNT 5.3% vs. 4.4%, p = 0.65). There was no difference in overall postoperative morbidity (38.4% vs. 46.3%, p = 0.08). Severe morbidity was similar with low anterior resection (9.1% vs. 15.3%, p = 0.10) and abdominoperineal resection (24.4% vs. 29.7%, p = 0.49). SC TNT did not increase the odds of severe morbidity relative to LCRT on multivariable analysis (OR 0.64, 95% CI 0.37-1.10). SC TNT does not increase morbidity after TME for rectal cancer relative to LCRT. Concern for surgical complications should not discourage the use of SC TNT when aiming to increase the likelihood of complete clinical response.

LBA25 Neoadjuvant short-course radiotherapy followed by camrelizumab plus chemotherapy versus long-course chemoradiotherapy followed by chemotherapy in locally advanced rectal cancer: A randomized phase III trial (UNION)

LBA25 Neoadjuvant short-course radiotherapy followed by camrelizumab plus chemotherapy versus long-course chemoradiotherapy followed by chemotherapy in locally advanced rectal cancer: A randomized phase III trial (UNION)

Randomized Controlled Trial of Neoadjuvant Short-Course Radiotherapy Followed by Consolidation Chemotherapy Versus Long-Course Chemoradiotherapy in Locally Advanced Rectal Cancer: Comparison of Overall Response Rates.

Management of locally advanced rectal cancer (LARC) is evolving with current emphasis on the addition of chemotherapy to short course radiotherapy (SCRT). We primarily aimed to analyse the difference in overall response rates between SCRT with sequential chemotherapy and standard long-course chemoradiotherapy (LCCRT)in LARC. After randomization, patients in arm A received 45Gy in 25 fractions over 5weeks with concurrent capecitabine while patients in arm B received 25Gy in 5 fractions over 1week followed by 3 cycles of CAPOX (capecitabine and oxaliplatin) chemotherapy. Clinical and radiological response assessment was made after the completion of neoadjuvant treatment, a week prior to surgery. Adjuvant chemotherapy was added to complete 6months of peri-operative chemotherapy. Surgery was performed between 8 and 10weeks of completion of radiation treatment in both arms. Of the 33 patients recruited in this study between February 2020 to July 2021, 17 patients were randomized to arm A and 16 to arm B. The rates of complete tumour regression were 23.1% in arm A versus 35.7% in arm B (p-value = 0.683). Pathological complete response (pCR) rate was 20% arm A versus 30% in arm B (0.446). A higher number of patients in arm B experienced grade 3 diarrhoea, whereas acute skin toxicity was seen only in arm A. SCRT had fewer treatment interruptions compared to LCCRT. SCRT followed by three cycles of CAPOX chemotherapy in the neoadjuvant setting is comparable to LCCRT in terms of tumour response. This may be a better alternative regimen with fewer treatment interruptions in a resource-limited setting.

Neoadjuvant short-course radiotherapy followed by chemotherapy plus camrelizumab versus long-course chemoradiotherapy followed by chemotherapy for patients with locally advanced rectal cancer: A randomized, multicenter, open-label phase 3 trial (Union).

TPS3638 Background: Short-course preoperative radiotherapy (SCPRT) and long-course chemoradiotherapy (LCCRT) are standard neoadjuvant treatments for locally advanced rectal cancer (LARC). Further, the RAPIDO trial found that SCPRT combined with consolidation chemotherapy produced better short- and long-term outcomes than SCPRT alone for patients with high-risk LARC. A phase 2, single-arm trial of neoadjuvant SCPRT followed by camrelizumab (an anti-PD-1 antibody) plus chemotherapy demonstrated promising short-term outcomes in patients with LARC. The Union trial is evaluating the efficacy and safety of neoadjuvant SCPRT followed by camrelizumab plus chemotherapy versus LCCRT followed by chemotherapy in patients with LARC. Methods: The Union trial is enrolling patients aged 18-75 with histologically confirmed clinical stage T3-4/N+ adenocarcinoma of the rectum, Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, and a tumor inferior margin less than 10 cm above the anal verge. Eligible patients are randomized in a 1:1 ratio to either arm A or arm B. Patients in arm A receive neoadjuvant treatment with SCPRT (a total of 25 Gy in 5 days) followed by camrelizumab (200 mg/m2 intravenous drip on day 1, every 3 weeks for 2 cycles) plus CAPOX (oxaliplatin 130 mg/m2 intravenous infusion over 2 hours on day 1, capecitabine 1000 mg/m2 oral twice daily, days 1–14, every 3 weeks for 2 cycles), surgery, and adjuvant treatment with camrelizumab plus CAPOX (6 cycles) followed by camrelizumab until the medication duration of camrelizumab reaches one year. Patients in arm B receive neoadjuvant treatment with LCCRT (capecitabine 825 mg/m2 twice daily, 5 days a week, combined with a total dose of 50.4 Gy in 28 days) followed by CAPOX (2 cycles), surgery, and adjuvant treatment with CAPOX (6 cycles). Randomization is stratified by clinical T stage (≤T3 vs T4) and clinical N stage (N0 vs N+). The primary endpoint is pathologic complete response (pCR). The secondary endpoints are 3-year event-free survival rate, overall survival, R0 resection rate, completion rate of neoadjuvant treatment, 3-year disease-free survival rate, tumor regression grading, safety, and quality of life. pCR is evaluated per the AJCC 8th Edition TRG scoring system as assessed by the blinded independent central review. Adverse events are graded by the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. Quality of life is assessed by the European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire Core 30. This study began enrollment in July 2021 with a planned enrollment of 230 patients. Clinical trial information: NCT04928807 .

Efficacy and safety of neoadjuvant preoperative short-course radiation followed by envafolimab plus CAPEOX in microsatellite stable (MSS)/mismatch repair proficient (pMMR) locally advanced rectal cancer.

134 Background: Chemoradiation is the standard neoadjuvant treatment for locally advanced rectal cancer. Microsatellite stable (MSS)/ mismatch repair proficient (pMMR) rectal cancer rarely responds to immune checkpoint inhibitor monotherapy, but combination with chemoradiation may improve sensitivity of MSS/pMMR tumors by inducing immune-stimulatory effects. Therefore, we aimed to investigate the efficacy and safety of patients treated with neoadjuvant preoperative short-course radiation followed by envafolimab plus CAPEOX for MSS/pMMR locally advanced rectal cancer. Methods: This is an open-label, single-center, phase ¢ò study. Patients (pts) with locally advanced rectal adenocarcinoma with MSS/pMMR were eligible. MMR protein expression was tested by immunohistochemistry (IHC) £¬and MSI status was confirmed by NGS (next generation sequencing). All pts included in this study underwent neoadjuvant short-course radiation (total dose of 5¡Á5Gy) in the first week after enrollment, then followed by 6 cycles of envafolimab (anti-PD-L1 inhibitor,150mg, d1, subcutaneous injection, QW) plus 2 cycles of CAPEOX in the next six weeks, and subsequently underwent total mesorectal excision (TME) in the ninth week. The primary endpoint is pathological complete response rate. Secondary endpoints include tumor regression grade (TRG), 3 year disease free survival, overall survival, toxicity, and quality of life (QoL). Results: This study intends to recruit 32 pts, and a total of 21 pts were enrolled from January 2022 to September 2022. Overall median age was 67 (42-79) years. 12 pts completed study designed treatment protocol (envafolimab plus CAPOX) followed with TME procedures, and 9 pts are still undergoing neoadjuvant treatment. All 12 pts achieved major partial response (MPR) evaluated by diffusion-weighted magnetic resonance imaging (DW-MRI), and 8 pts (8/12,76.6%) achieved pCR. During neoadjuvant treatment period, 20 pts (20/21, 95.2%) presented with treatment-related AEs (TRAEs) of any grade, 18 pts (18/21, 85.7%) had grade 1-2 and one each pts had grade 3 and 4 thrombocytopenia (2/21, 9.5%). The most common TRAEs were sensation of rectal tenesmus. Conclusions: Neoadjuvant preoperative short-course radiation followed by envafolimab plus CAPEOX in MSS/pMMR locally advanced rectal cancer achieved a promising pathologic response. Meanwhile, this combination neoadjuvant therapy is safe and worthy of application to clinical practice. (Funded by Sir Run Run Shaw Hospital Zhejiang University School of Medicine.) Clinical trial information: NCT05216653 .

Neoadjuvant Short-Course Radiotherapy Followed by Consolidation Chemotherapy before Surgery for Treating Locally Advanced Rectal Cancer: A Systematic Review and Meta-Analysis.

Neoadjuvant short course radiotherapy (SCRT) followed by consolidation chemotherapy (CCT) is an alternative treatment for locally advanced rectal cancer (LARC). We performed this systematic review and meta-analysis to explore the tumor response and oncological outcomes of this new approach compared to conventional chemoradiotherapy (CRT). An online search of the PubMed, Embase, and Cochrane Library databases was performed. This review included 7507 patients from 14 different cohorts. The pCR rate was higher with SCRT + CCT than that with CRT (RR: 1.60; 95% CI: 1.35–1.91; p < 0.01). SCRT + CCT provided a higher ypN0 response (RR: 1.06; 95% CI: 1.01–1.12; p = 0.02). There were no differences in R0 resection and positive CRM rates; however, more sphincter-preservation surgeries were performed in the SCRT + CCT arm (RR: 1.06; 95% CI: 1.01–1.11; p = 0.02). There was no difference in the OS and DFS between the SCRT + CCT and the CRT arms (OS: HR: 0.85, p = 0.07; DFS: HR: 0.88, p = 0.08). The compliance and toxicity were comparable between the SCRT and CRT groups. In the subgroup analysis, patients who underwent four or more cycles of CCT had better pCR and DFS events. Therefore, SCRT followed by consolidation chemotherapy might be an effective alternative treatment for LARC.