Primary Rectal Tumor Research Articles

Selection of rectal cancer patients for organ preservation after neoadjuvant therapy: value of T2W-MRI signal intensity.

Organ preservation strategies have been widely implemented for rectal cancer (RC) patients with a good response after neoadjuvant chemoradiation (nCRT). However, to accurately select eligible patients remains one of the key diagnostic challenges. To identify eligible candidates for organ preservation after nCRT in RC, by identifying luminal response and lymph node metastases, based on T2W-MRI signal intensities. A total of 171 RC patients underwent MRI before and after nCRT. The primary tumor (pre-nCRT-MRI) and tumor remnant (post-nCRT-MRI) were manually delineated. Ten signal intensity features were extracted and delta features were calculated by subtraction. Histopathological evaluation classified patients as lymph node negative (ypN0) or positive (ypN+), and as good responders (GR) or partial/poor responders (PR). Five models were constructed based on the timing of imaging. 42/170 (25%) patients had ypN+, and 72/152 (47%) patients were considered GR. Univariate analysis showed 13/40 signal intensity features were significantly different between luminal response groups and 4/40 between nodal response groups. In multivariate analysis, the Baseline + Restaging-model yielded the best results for both luminal and nodal response with AUCs in the test set of 0.81 (95% CI=0.67-0.95) and 0.74 (95% CI=0.59-0.90), respectively. To identify PR, the Delta-model yielded an AUC of 0.72 (95% CI=0.56-0.89) and the Delta + Restaging-model an AUC of 0.81 (95% CI=0.67-0.95), both were not able to differentiate nodal response. The models including solely baseline or restaging features were not predictive. T2W-MRI signal intensities of the primary rectal tumor are related to the luminal and nodal response after nCRT and hold promise to identify patients eligible for organ preservation.

Patterns of metastatic spread and survival outcomes for stage IV left-sided colon vs. rectal cancers: A real-world analysis.

75 Background: A growing body of literature has reported differences in biology, metastatic potential, and outcomes among patients with colorectal cancer based on the sidedness of their primary tumor (right vs. left). Left-sided primary tumors have comprised both colon and rectal tumors, despite differences in venous and lymphatic drainage patterns and treatment paradigms. The present work sought to investigate patterns of metastases and survival outcomes among patients with left sided colon primary tumors and rectal primary tumors. We hypothesized that these two disease sites metastasize differently and exhibit different survival patterns based on metastatic site. Methods: The National Cancer Database (NCDB) was queried for all patients with a diagnosis of metastatic left-sided colon (splenic flexure, descending colon, rectosigmoid) or rectal adenocarcinoma with known primary site and known metastatic site(s) between 2010 and 2021 using parameters outlined in the NCDB Data Dictionary. Patients with left-sided colon primaries (LP) were compared to patients with rectal primaries (RP) along clinicodemographic parameters. Incidence of metastases to the liver, lungs, bone, brain, and non-regional lymph nodes were also compared. Multivariable survival analyses were performed to analyze differences in overall survival (OS). Results: Among 84,958 patients, 51,931 (61.1%) had LP while 33,027 (38.9%) had RP. Patients with RP were less likely to have liver metastases than those with LP (79.4% vs. 90.3%), but more likely to have lung (40.7% vs. 29.2%), bone (8.3% vs. 6.0%), and distant lymph node metastases (11.3% vs. 8.6%) (all p<0.001). Compared to patients with LPs, patients with RP were less likely to undergo surgery to the primary tumor (25.1% vs. 46.3%) or any metastatic site (15.3% vs. 18.8%), more likely to receive chemotherapy for metastatic disease (80.8% vs. 75.2%), and more likely to receive radiation to the primary site (17.7% vs. 4.3%) (all p<0.001). Additionally, patients with RP had longer median OS than those with LP (27.3 months vs. 26.4 months, p<0.001). On multivariable analysis controlling for age, gender, tumor grade, RAS mutation status, MSI status, CEA level, clinical T and N category, and treatment details, patients with RP with liver metastases (HR 0.91, 95% CI 0.89-0.92), lung metastases (HR 0.85, 95% CI 0.82-0.87), and bone metastases (HR 0.89, 95% CI 0.84-0.95) (all p<0.001) demonstrated improved OS compared to those with LP. Conclusions: Patterns of metastases, treatment regimens, and, in certain instances, survival outcomes, differ among patients with stage IV left-sided colon cancer and rectal cancer. Future work evaluating the implications of sidedness in colorectal cancer as well as future staging efforts should consider assessing left-sided colon cancer separately from rectal cancer, as these demonstrate distinct clinical behavior and outcomes.

Colon and rectal peritoneal carcinomatosis: are we mixing apples with oranges? A propensity score-matched analysis.

Rectal cancer is universally considered a different disease entity as compared to colon cancer, except when dealing with colorectal peritoneal carcinomatosis (PC), in which the two cancers are deemed as the same one. The present study aims to investigate the influence of primary tumor location (colon vs. rectum) on oncologic outcomes in patients undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for colorectal peritoneal metastases. Data from three referral centers undergoing CRS plus HIPEC for PC of colorectal origin were prospectively collected. The primary outcomes were overall survival (OS) and disease-free survival (DFS) according to primary tumor location (colic vs. rectal). Univariate and multivariate analyses were performed using the Cox proportional hazard model first on the total number of patients. Then, a propensity score matching using the nearest-neighbour method with a 1:1 ratio was performed. The study included 167 patients: 126 colic and 41 rectal PC. After propensity score matching, rectal primary tumor location was independently predictive of a lower DFS (HR 1.91; 95%CI 1.06-3.45; p = 0.031) but not of a lower OS (HR 1.12; 95%CI 0.57-2.21; p = 0.73). Post-matching 3-year DFS rates were 49.2% (95%CI 34,3-70,5%) and 19.4% (95%CI 9,4-40,2%) for colic and rectal PC, respectively. The present study shows a significantly worse DFS for rectal cancer PC undergoing CRS and HIPEC compared to colon cancer PC, suggesting a possible need for dedicated pathways for rectal PC patients and posing a question for rectal PC to be considered as a unique disease entity.

Long-Term Follow-Up of Patients with Advanced Colorectal Liver Metastasis: A Survival Analysis from the Randomized Controlled Multicenter Trial LIGRO.

The objective of this study was to evaluate the long-term oncological outcomes of patients with colorectal liver metastasis (CRLM) randomized for associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) or 2-stage hepatectomy (TSH). For advanced CRLM, TSH or ALPPS may be needed for tumor freedom. The randomized, controlled, multicenter trial LIGRO showed an increased resection rate in patients who underwent ALPPS but no difference in morbidity or mortality. The 2-year survival analysis revealed better overall survival in the ALPPS group. Here, the long-term survival analysis from the LIGRO trial is reported. In the LIGRO trial, 100 patients were randomized to TSH or ALPPS, with the option of rescue ALPPS if insufficient growth was found after the initial step of TSH. Patients were enrolled between June 2014 and August 2016. Follow-up data for this study were collected between November 2022 and February 2023. In total, 16 patients were alive at the end of the follow-up period. The estimated median follow-up time was 93 months. Estimated median overall survival times were 45 months in the ALPPS group and 27 months in the TSH group (P = 0.057), with 5-year survival rates of 31% and 20%, respectively. Positive prognostic factors were liver tumor-free status at the first follow-up and rectal primary tumor. Negative prognostic factors were extrahepatic disease and increasing CLRM size. Liver tumor-free status is a predictor of long-term survival, along with extrahepatic disease, large CRLM size, and rectal primary tumor. Survival did not significantly differ between patients treated with ALPPS or TSH.

Clinical characteristics and survival analysis in patients with isolated pulmonary metastases from colorectal cancer (CRC).

60 Background: Recent studies seem to indicate that patients with metastatic colorectal cancer (mCRC) with exclusive pulmonary metastatic disease have better outcomes than those with other metastatic sites. The aim of this study is to identify differences in clinical and survival characteristics between the two groups in a cohort of a third level hospital. Methods: We retrospectively analyzed a sample of 569 patients with mCRC in a tumor registry from 2015 to 2021, studying clinical and molecular characteristics, as well as overall survival data of patients with isolated pulmonary metastases, versus the rest of patients. Results: Of the total sample analyzed, 61 patients (10.7%) had isolated pulmonary metastases. In these patients, several clinical characteristics were more frequent: primary rectal tumor (52.5% vs 23.4%, p < 0.000), resected primary tumor (95.1% vs 78.9%, p = 0.0026), metachronous metastatic disease (62.3% vs 42%, p = 0.0025) and complete response rate to the first line of treatment (19.3% vs 9.9%, p = 0.026). Furthermore, analytically, these patients were more likely to have normal CEA (75% vs 38.3%, p < 0.000), CA 19.9 (84.3% vs 57.7%, p = 0.0002) and LDH (91.1% vs 66.5%, p = 0.0007) levels. In our cohort, we found no statistically significant differences in tumor mutational status (KRAS, NRAS, BRAF, PI3K and HER2). There were no patients with exclusive pulmonary metastatic disease and microsatellite instability (MSI). 70.3% of patients with isolated pulmonary metastases received lung metastasectomy, and up to 58.3% received a second metastases surgery. We also found a numerical benefit in terms of overall survival (OS) in patients with exclusive metastatic lung disease, although it did not reach statistical signification (median OS 77.3 vs 58.1 months, HR for death 0.70, 95% CI, 0.49 – 1.01, p = 0.083). Conclusions: In our cohort, patients with isolated pulmonary metastases were more likely to have rectal tumors, primary tumor resection, metachronous metastatic disease, higher rate of complete responses and normal CEA, CA 19.9 and LDH levels, with a possible benefit in terms of OS.

Pneumonia with Intense 68Ga-FAPI Uptake Mimicking Metastasis on 68Ga-FAPI PET/CT in a Patient with Rectal Cancer.

A 70-year-old man with newly diagnosed rectum adenocarcinoma was referred to 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for staging, and 68Ga-fibroblast activation protein inhibitor (FAPI)-04 PET/CT for ongoing trial. Both 18F-FDG PET/CT and 68Ga-FAPI-04 PET/CT showed intense uptake in the primary rectal tumor, and also in nodular areas in the right lung. Due to intense 68Ga-FAPI-04 and 18F-FDG uptake, the lung lesions were considered as metastases. However the lesions were reduced in size on CT after 20 days antibiotherapy and diagnosed as pneumonia.

Perioperative and Oncological Outcomes of Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Peritoneal Metastasis of Rectal Origin

BackgroundThe peritoneum is a common metastatic site of colorectal cancer (CRC) and associated with worse oncological outcomes. Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) has been shown to improve outcomes in selected patients. Studies have demonstrated significant difference in survival of patients with primary colon and rectal tumors both in local and in metastatic setting; but only few assessed outcomes of CRS/HIPEC for rectal and colon tumors. We studied the perioperative and oncological outcomes of patients undergoing CRS/HIPEC for rectal cancer. MethodsA retrospective analysis of a prospectively maintained database between 2009 and 2021 was performed. Results199 patients underwent CRS/HIPEC for CRC. 172 patients had primary colon tumors and 27 had primary rectal tumors. Primary rectal location was associated with longer surgery (mean 4.32, hours vs 5.26 h, p = 0.0013), increased blood loss (mean 441cc vs 602cc, p = 0.021), more blood transfusions (mean 0.77 vs 1.37units, p = 0.026) and longer hospitalizations (mean 10 days vs 13 days, p = 0.02). Median disease-free survival (DFS) was shorter in rectal primary group; 7.03 months vs 10.9 months for colon primaries (p = 0.036). Overall survival was not statistically significant; 53.2 months for rectal and 60.8 months for colon primary tumors. Multivariate analysis indicated origin (colon vs rectum) and Peritoneal Cancer Index to be independently associated with DFS. ConclusionsPatients with rectal carcinoma undergoing CRS/HIPEC for peritoneal metastasis had worse peri-operative and oncological outcomes. Overall survival was excellent in both groups. This data may be used for risk stratification when considering CRS/HIPEC for patients with rectal primary.

High OCT4 Expression Might Be Associated with an Aggressive Phenotype in Rectal Cancer.

Rectal cancer (RC) is one of the most common malignant neoplasms, and cancer stem cells (CSCs) of the intestinal tract have been implicated in its origin. The oncofetal protein OCT4 has been linked to neoplastic processes, but its role and clinical significance in RC are unknown. This study investigates the expression of the stem cell marker OCT4 related to clinical-pathological characteristics and its clinical significance in RC patients. The expression level of stem cell marker OCT4 was analyzed in 22 primary rectal tumors by western blot. The association between OCT4 protein expression and the clinical-pathological features of tumors was evaluated by χ2 test and Fisher's exact test. We demonstrated that the expression of the stem cell marker OCT4 was observed in tumor tissue but not adjacent non-tumor tissue. High expression of the stem cell marker OCT4 was significantly associated with histological differentiation grade (p = 0.039), tumor invasion level (p = 0.004), lymph node involvement (p = 0.044), tumor-node-metastasis (TNM) stage (p = 0.002), and clinical stage (p = 0.021). These findings suggest that high OCT4 expression is associated with a more aggressive RC phenotype, with a greater likelihood of progression and metastasis. These results shed light on the importance of targeting this CSC marker to attenuate RC progression.

Hepatectomy Before Primary Tumor Resection as Preferred Approach for Synchronous Liver Metastases from Rectal Cancer.

For patients with synchronous liver metastases (LM) from rectal cancer, a consensus on surgical sequencing is lacking. We compared outcomes between the reverse (hepatectomy first), classic (primary tumor resection first), and combined (simultaneous hepatectomy and primary tumor resection) approaches. A prospectively maintained database was queried for patients with rectal cancer LM diagnosed before primary tumor resection who underwent hepatectomy for LM from January 2004 to April 2021. Clinicopathological factors and survival were compared between the three approaches. Among 274 patients, 141 (51%) underwent the reverse approach; 73 (27%), the classic approach; and 60 (22%), the combined approach. Higher carcinoembryonic antigen level at LM diagnosis and higher number of LM were associated with the reverse approach. Combined approach patients had smaller tumors and underwent less complex hepatectomies. More than eight cycles of pre-hepatectomy chemotherapy and maximum diameter of LM > 5 cm were independently associated with worse overall survival (OS) (p = 0.002 and 0.027, respectively). Although 35% of reverse-approach patients did not undergo primary tumor resection, OS did not differ between groups. Additionally, 82% of incomplete reverse-approach patients ultimately did not require diversion during follow-up. RAS/TP53 co-mutation was independently associated with lack of primary resection with the reverse approach (odds ratio: 0.16, 95% CI 0.038-0.64, p = 0.010). The reverse approach results in survival similar to that of combined and classic approaches and may obviate primary rectal tumor resections and diversions. RAS/TP53 co-mutation is associated with a lower rate of completion of the reverse approach.

Retrospective study of combined pelvic organ resection in the treatment of primary and recurrent pelvic malignant tumors.

e15635 Background: For locally advanced or recurrent pelvic malignancies, combined pelvic organ resection has been used to treat rectal, bladder, gynecological and other related malignancies. As an interdisciplinary and high-risk operation, the perioperative safety and future information are often very limited. We retrospectively analyzed the efficacy of PE surgery in our institution. Methods: In this retrospective study, 59 patients with pelvic malignant tumors received PE surgery from July 2015 to July 2021. They were divided into two groups according to the location of the disease: rectal tumor group (n = 40) and cervical cancer group (n = 19). The baseline data, gene detection reports, pathological reports, perioperative conditions and prognosis were analyzed. The two groups were compared by independent sample t-test; Comparison between groups χ2 test, the survival curve was drawn by Kaplan-Meier method and compared by log rank test. Results: Among these 59 patients treated with PE, the rectal tumor group and the cervical cancer group did not differ significantly in terms of demographics, operative time, hospital stay, intraoperative blood loss, and rates of use of preoperative and intraoperative radiotherapy. Compared with the two groups, the overall incidence of postoperative complications was 37% in the group with rectal tumours and 26% in the group with perineal wound infection being the most common, cervical cancer 46% and urinary tract infection being the most common. Comparing the postoperative survival OS between patients in the rectal tumor group and those in the cervical cancer group, the former was better, with 5-year overall survival rates of 37% in the rectal tumor group and 28% in the cervical cancer group. Within the group of rectal tumours, however, there are differences in survival between patients with primary (LARC) and recurrent (lrrc) rectal tumours; Patients with LARC have shown a significant survival benefit postoperatively, with 5-year overall survival rates of 40% for patients with LARC and 27% for patients with lrrc. OS was significantly better in patients with well differentiated tumors, N0 stage, and high microsatellite instability (MSI). On the basis of univariate analysis, poorly differentiated tumor, regional lymph node dissemination, MSI, and no chemotherapy received perioperatively were significant predictors of poor survival (P < 0.05). Conclusions: PE is currently an effective treatment for pelvic malignancies with aggressive radical resection of lesions, which can effectively improve their cure rate, improve quality of life, and careful patient selection can optimize outcomes.

Polypectomy or excisional biopsy versus combination polypectomy or excisional biopsy with interventional radiology local tumor destruction for rectal cancer: A SEER database analysis.

e15658 Background: Rectal cancer is a common and potentially debilitating form of gastrointestinal cancer. Despite advances in surgical and systemic therapies, a significant proportion of patients present with locally advanced or recurrent disease. Interventional radiology (IR) has emerged as a crucial tool in the management of rectal cancer, offering a number of minimally invasive treatments aimed at locally destroying the tumor. This study aims to evaluate the efficacy and prognostic significance of combining IR treatments with polypectomy or excisional biopsy in the management of rectal cancer, compared to polypectomy or excisional biopsy alone. Methods: We queried the Surveillance, Epidemiology, and End Results (SEER) database for patients diagnosed with primary rectal cancer from the cecum to the sigmoid (primary site codes C209), including the appendix, diagnosed between 2000-2019. Patients were included if management of the primary tumor included either excisional biopsy, polypectomy, or local tumor destruction (LTD) via photodynamic therapy, electrocautery, cryosurgery, or laser ablation (surgical codes 21-24). Variables included for statistical analyses were age at diagnosis, sex, race, stage, and surgical management subtype status. Results: A total of 24309 patients were collected from this search of which 1437 patients were selected that had undergone a combination polypectomy or excisional biopsy with LTD, 15005 patients underwent polypectomy alone, 7481 patients underwent excisional biopsy alone, 386 patients underwent curette and fulguration. On Kaplan-Meier, combination treatment showed a worse mean survival than polypectomy alone (p < 0.01). Combination treatment showed better mean survival than excisional biopsy alone ( < 0.001). The combination treatment showed similar survivability to curette and fulguration. The one-, three-, and five-year survival rates of combination treatment were 98.5%, 95.8%, and 94.8%, respectively, which is significantly greater than excisional biopsy at all points but significantly worse than polypectomy alone at all time points (p’s < 0.001). On Cox regression, combination treatment showed no difference in survival to polypectomy alone and curette fulguration. Combination treatment survival was significantly better than excisional biopsy alone (p < 0.001). Additionally, older age (p < 0.001), regional spread of tumor (p < 0.001), and distant spread of tumor (p < 0.0001) were all associated with worse survival outcomes. Conclusions: Combination polypectomy or excisional biopsy with IR LTD procedures are associated with improved survival compared to excisional biopsy alone for the treatment of rectal cancer. Our findings suggest that IR procedures may serve as an effective adjunct treatment option for primary rectal tumor management.

Efficacy of concurrent radiotherapy in patients with locally advanced rectal cancer and synchronous metastasis receiving systemic therapy.

Neoadjuvant chemoradiotherapy followed by total mesorectal excision is the standard treatment for patients with nonmetastatic locally advanced rectal cancer (LARC). However, for patients with LARC and synchronous metastasis, the optimal treatment strategy and sequence remain inconclusive. In the present study, we evaluated the efficacy and safety of concurrent radiotherapy in patients with de novo metastatic rectal cancer who received chemotherapy and targeted therapy. We retrospectively reviewed the data of 63 patients with LARC and synchronous metastasis who received intensive therapy at the study hospital between April 2015 and November 2018. The included patients were divided into two groups: RT-CT, those who received systemic chemotherapy with targeted therapy and concurrent radiotherapy (for primary rectal cancer), and CT, those who received only systemic chemotherapy with targeted therapy. Treatment response was better in the RT-CT group than in the CT group. The rate of primary tumor resection (PTR) was higher in the RT-CT group than in the CT group (71.4% and 42.9%, respectively; P = .0286). The RT-CT group exhibited considerably longer local recurrence-free survival (P = .0453) and progression-free survival (PFS; from 13.3 to 22.5 months) than did the CT group (P = .0091); however, the groups did not differ in terms of overall survival (OS; P = .49). Adverse events were almost similar between the groups, except frequent diarrhea, the prevalence of which was higher in the RT-CT group than in the CT group (59.5% and 23.8%, respectively; P = .0075). In the era of biologics, radiotherapy may increase the resectability of primary rectal tumors, reducing the risk of locoregional failure and prolonging PFS. Concurrent pelvic radiotherapy may not substantially improve OS, which is indicated by metastasis. Hence, the resection of the distant metastases may be essential for improving long-term OS. To further determine the efficacy of concurrent radiotherapy, additional prospective, randomized studies must combine preoperative pelvic radiotherapy with PTR and metastectomy to treat patients with stage IV LARC.

Multiple distant metastases arising from a single, low-grade rectal neuroendocrine tumor: an autopsy case report

BackgroundRectal neuroendocrine neoplasms are rare epithelial neoplasms of the rectum. The incidence of these tumors has increased over the past decades. However, many questions remain unanswered regarding their clinicopathology, including the possible mechanisms in which these tumors may grow and metastasize.Case presentationIn this case report, we report the findings of an autopsy of a 65-year-old Japanese woman diagnosed with multiple liver metastases from a single, low-grade rectal neuroendocrine tumor. The diagnosis was made in late 2018 to early 2019, and subsequently the patient underwent several rounds of standard chemotherapy. However, due to unfavorable side effects, she opted for palliative care at our hospital instead from December 2020. The patient’s condition was generally stable for the next 17 months, but in May 2022, she was hospitalized for increased abdominal pain. Despite enhanced pain control therapy, she eventually passed away. An autopsy was conducted to determine the exact cause of death. The primary rectal tumor was found to be small, but showed strong histological evidence of venous invasion. Metastases in the liver, pancreas, thyroid gland, adrenal glands, and vertebrae were also present. On the basis of the histological evidence obtained, we deduced that the tumor cells may have mutated and gained multiclonality as they spread vascularly to the liver, contributing to the distant metastases.ConclusionsThe results from this autopsy may provide an explanation for the possible mechanism by which small, low-grade rectal neuroendocrine tumors metastasize.

The repeatability and consistency of different methods for measuring the volume parameters of the primary rectal cancer on diffusion weighted images.

To determine the reproducibility of measuring the gross total volume (GTV) of primary rectal tumor with manual and semi-automatic delineation on the diffusion-weighted image (DWI), examine the consistency of using the same delineation method on DWI images with different high b-values, and find the optimal delineation method to measure the GTV of rectal cancer. 41 patients who completed rectal MR examinations in our hospital from January 2020 to June 2020 were prospectively enrolled in this study. The post-operative pathology confirmed the lesions were rectal adenocarcinoma. The patients included 28 males and 13 females, with an average age of (63.3 ± 10.6) years old. Two radiologists used LIFEx software to manually delineate the lesion layer by layer on the DWI images (b=1000 s/mm2 and 1500 s/mm2) and used 10% to 90% of the highest signal intensity as thresholds to semi-automatically delineate the lesion and measure the GTV. After one month, Radiologist 1 performed the same delineation work again to obtain the corresponding GTV. The inter- and intra-observer interclass correlation coefficients (ICC) of measuring GTV using semi-automatic delineation with 30% to 90% as thresholds were all >0.900. There was a positive correlation between manual delineation and semi-automatic delineation with 10% to 50% thresholds (P < 0.05). However, the manual delineation was not correlated with the semi-automatic delineation with 60%, 70%, 80%, and 90% thresholds. On the DWI images with b=1000 s/mm2 and 1500 s/mm2, the 95% limit of agreement (LOA%) of measuring GTV using semi-automatic delineation with 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% thresholds were -41.2~67.4, -17.8~51.5, -16.1~49.3, -26.2~50.1, -42.3~57.6, -57.1~65.4, -67.3~66.5, -101.6~91.1, -129.4~136.0, and -15.3~33.0, respectively. The time required for GTV measurement by semi-automatic delineation was significantly shorter than that of manual delineation (12.9 ± 3.6s vs 40.2 ± 13.1s). The semi-automatic delineation of rectal cancer GTV with 30% threshold had high repeatability and consistency, and it was positively correlated with the GTV measured by manual delineation. Therefore, the semi-automatic delineation with 30% threshold could be a simple and feasible method for measuring rectal cancer GTV.

Trends of sphincter-preserving surgeries for low lying rectal cancer: A 20-year experience in China.

Over the last 2 decades, patients with low rectal cancer have had better outcomes from improvements in surgical techniques in sphincter preservation. We aimed to quantify the trends in sphincter-preserving surgeries for low rectal cancer over 20 years in a top tertiary hospital in China. Between 1999 and 2021, a cohort of patients with primary malignant rectal tumor ≤5cm from the anal verge and who received elective surgeries at Changhai Hospital, Shanghai, China, was identified. Data were extracted from electronic medical records. A Joinpoint Regression Model was used to analyze trends in surgical procedures by average annual percentage change (AAPC). Adjusted Cox proportional hazards regression model was used to assess overall survival. Among a total of 4,172 patients during the study period, 3,111 (74.6%) underwent a sphincter-preserving surgery and 1,061 (25.4%) received APR. Sphincter-preserving surgery increased 3.6% per year (95%CI, 2.3-4.9). Low anterior resection was the most performed procedure (86.3%) and maintained a steady trend, while intersphincteric resection increased 49.4% annually (95%CI, 19.5-86.7) after initiation. Laparoscopic techniques increased 15.1% per year (95%CI, 8.4-43.4) after initiation. Sphincter-preserving surgery increased annually for tumors ≤2cm, 2-≤3cm and 3-≤4cm from the anal verge (AAPC 7.1, 4.5-9.8; 4.7, 3.1-6.3; 2.7, 1.7-3.6, respectively). Furthermore, patients with sphincter-preserving surgery had a better overall survival than abdominoperineal resection (APR) patients (adjusted HR 0.78, 95% CI, 0.65-0.93, p=.01). Utilization of sphincter-preserving surgeries increased significantly over the last 20 years. Patients with low rectal cancer who underwent sphincter preservation had better survival than similar patients who underwent APR.

Impact of endorectal filling on interobserver variability of MRI based rectal primary tumor delineation

BackgroundOnline adaptive MR-guided radiotherapy allows for the reduction of safety margins in dose escalated treatment of rectal tumors. With the use of smaller margins, precise tumor delineation becomes more critical. In the present study we investigated the impact of rectal ultrasound gel filling on interobserver variability in delineation of primary rectal tumor volumes. MethodsSix patients with locally advanced rectal cancer were scanned on a 1.5 T MRI-Linac without (MRI_e) and with application of 100 cc of ultrasound gel transanally (MRI_f). Eight international radiation oncologists expert in the treatment of gastrointestinal cancers delineated the gross tumor volume (GTV) on both MRI scans. MRI_f scans were provided to the participating centers after MRI_e scans had been returned. Interobserver variability was analyzed by either comparing the observers’ delineations with a reference delineation (approach 1) and by building all possible pairs between observers (approach 2). Dice Similarity Index (DICE) and 95 % Hausdorff-Distance (95 %HD) were calculated. ResultsRectal ultrasound gel filling was well tolerated by all patients. Overall, interobserver agreement was superior in MRI_f scans based on median DICE (0.81 vs 0.74, p < 0.005 for approach 1 and 0.76 vs 0.64, p < 0.0001 for approach 2) and 95 %HD (6.9 mm vs 4.2 mm for approach 1, p = 0.04 and 8.9 mm vs 6.1 mm, p = 0.04 for approach 2). Delineated median tumor volumes and inter-quartile ranges were 26.99 cc [18.01–50.34 cc] in MRI_e and 44.20 [19.72–61.59 cc] in MRI_f scans respectively, p = 0.012. ConclusionsAlthough limited by the small number of patients, in this study the application of rectal ultrasound gel resulted in higher interobserver agreement in rectal GTV delineation. The endorectal gel filling might be a useful tool for future dose escalation strategies.

A New Anorectal Melanoma Cell Line Derived from a Primary Human Rectal Tumor.

Anorectal melanoma is a rare disease with a poor prognosis. Symptoms are often nonspecific, which complicates preoperative diagnosis. Here, we describe the establishment of MELS, a new anorectal melanoma cell line derived from resection of a rectal tumor in a 40-year-old Japanese man. Histological, electron microscopic, and immunohistochemical features of S-100, HMB-45, Melan-A, and NSE positivity of the tumor were typical of surgically resected anorectal melanoma. MELS cells are round or oval and have sharp thorn-like protrusions on some or all cell membranes. The cells form irregular attached colonies with numerous floating cells in two-dimensional culture. Transmission electron microscopy revealed that some MELS cells have cytoplasmic melanosomes. Immunocytochemically, MELS cells and surgical tissues had the same staining pattern. MELS cells had lower growth rates than Caco-2 (a colon adenocarcinoma cell line) and A375 (a cutaneous melanoma cell line) cells. Oxaliplatin and irinotecan were more effective in MELS cells than in Caco-2 and A375 cells. No previous report provided detailed clinical information on an anorectal melanoma cell line. Thus, MELS cells should improve our understanding of the biological characteristics of anorectal melanoma and provide a novel platform for examining the effects of therapies for anorectal melanoma.

Trend of sphincter-preserving surgeries for resectable low rectal cancer: A 20-year experience in China.

3615 Background: Over the last decades, patients with low rectal cancer have realized better functional, morbidity, and quality-of-life outcomes from improvements in surgical techniques in sphincter preservation. We aimed to quantify the trend in sphincter-preserving surgeries for low rectal cancer over 20 years in China. Methods: Between November 1999 and October 2021, a cohort of patients with pathologically confirmed primary malignant rectal tumor ≤5cm from the anal verge and who received selective surgery at Changhai Hospital, was identified. Demographic and clinical data were extracted from electronic medical records. Survival data were collected from outpatient medical records and follow-up phone interviews. A Joinpoint Regression Model was used to analyze trends in surgical procedures by average annual percentage change (AAPC). A Cox proportional hazards regression model adjusting for demographic and clinicopathological confounders was used to assess the overall survival for patients with sphincter-preserving surgery vs. abdominoperineal resection (APR). Results: Among 19,276 patients with colorectal cancer, 4,072 (21.1%) had a tumor in the low rectum during the study period; 3,025 (74.2%) underwent a sphincter-preserving surgery and 1,047 (25.7%) received APR. Sphincter-preserving surgery increased 3.6% per year (AAPC 3.6, p=.006). Anterior resection was the most performed procedure (86.3%) and maintained a steady trend (AAPC 0.13, p=.49), while intersphincteric resection (including conformal sphincter preservation operation) increased 49.4% annually (AAPC 49.4, p=.003). Laparoscopic techniques increased 15.1% per year (AAPC 15.1, p=.035). Sphincter-preserving surgery increased annually for tumors ≤2cm, 2-3cm and 3-4cm from the anal verge (AAPC 7.08, p=.001; 4.69, p=.001; 2.66, p=.001, respectively). A total of 2,854 patients had sufficient vital status data for inclusion in the survival analysis. The characteristics of those with and without a follow-up encounter were comparable. Patients with sphincter-preserving surgery had a lower risk of death compared to APR (adjusted HR 0.78, 95% CI, 0.65-0.93, p=.01). Conclusions: Utilization of sphincter-preserving surgeries increased significantly over the last 20 years. Patients with low rectal cancer who underwent sphincter preservation had better survival than similar patients who underwent APR.[Table: see text]

Oligometastatic Rectal Adenocarcinoma Treated With Short-Course Radiation Therapy and Chemotherapy With Nonoperative Intent of the Primary for Locoregional Complete Responders

PurposeNonoperative management with short-course radiation therapy (SCRT) as a component of definitive therapy for oligometastatic rectal cancer has not been previously reported. This single-institution retrospective analysis evaluates treatment with SCRT in combination with chemotherapy (SCRT-CTX) with nonoperative intent for patients with a locoregional clinical complete response (cCR). Methods and MaterialsThirty-six patients with newly diagnosed oligometastatic rectal cancer were treated with SCRT-CTX between January 1, 2018, and May 31, 2020. Digital rectal examination, endoscopy, and imaging (computed tomography or magnetic resonance imaging) were used to determine cCR. Medically operable patients without cCR underwent surgical resection of the primary rectal tumor. Patients with cCR who experienced a local failure received salvage surgery. Rates of hospitalization related to primary tumor disease and pelvic symptoms were reviewed. Overall survival (OS) and progression free survival were evaluated. ResultsSeventeen percent (6/36) of patients achieved cCR after SCRT-CTX. Eleven percent (4) of patients experienced a local failure. OS for all patients was 83% (71%-96%) at 12 months and 57% (41%-80%) at 24 months. Progression free survival for all patients was 56% (41%-74%) at 12 months and 10% (3.1%-35%) at 24 months. On multivariate analysis, having received more than 4 months of chemotherapy (hazard ratio = 0.21; 95% confidence interval, 0.06-0.71; P = .01) and definitive treatment of metastatic site (hazard ratio = 0.17; 95% confidence interval, 0.05-0.66; P = .01) predicted for improved OS. The number of patients requiring hospitalization due to obstruction (8/36, 22%), rectal bleeding (5/36, 14%), or need for permanent ostomy placement (5/36, 14%) was low, and there was a decrease in endorsement of obstructive symptoms and rectal bleeding after completion of SCRT-CTX. ConclusionsSCRT-CTX with nonoperative intent for patients with a locoregional cCR may be a reasonable treatment option for patients with newly diagnosed oligometastatic rectal adenocarcinoma and demonstrates excellent control of pelvic disease and symptoms. Increased duration of chemotherapy within the treatment paradigm may improve oncologic outcomes.

Rectal cancer diagnosed after resection of isolated brain metastasis

BackgroundBrain metastasis of colorectal cancer is infrequent, and isolated brain metastases are more infrequent. Thus, when neurological symptoms, such as paralysis or disturbance of consciousness appear, there is a high probability that the cancer has spread to other organs.Case presentationHere, we present a 64-year-old man with a progressive headache, decreased motivation, and aphasia who was diagnosed with a brain tumor in the left frontal region. He underwent a craniotomy, and the brain tumor was diagnosed as adenocarcinoma. We performed a colonoscopy and diagnosed rectal cancer without other distant metastases. After whole-brain radiotherapy (WBRT), low anterior resection for primary rectal tumor was performed using a robotic system. The patient was discharged in good condition and received postoperative adjuvant therapy for rectal cancer. He showed no signs of recurrence after 1 year of follow-up.ConclusionsWe described a rare case of rectal cancer that was diagnosed after resection of isolated brain metastasis. A good prognosis was achieved with surgery and WBRT.