Optimal neoadjuvant strategy for signet ring cell carcinoma of the rectum-Is TNT the solution?

Patient-Derived Organoids and Xenografts Uncover Therapeutic Vulnerabilities in Colorectal Signet Ring Cell Carcinomas

PURPOSE

Identifying therapeutic targets for signet ring cell carcinoma (SRCC) of the colon and rectum is a clinical challenge because of the lack of patient-derived organoids (PDO) or patient-derived xenografts (PDX). To address this unmet need, we present a robust method for establishing PDO and PDX models. We demonstrate that these models identify novel therapeutic strategies targeting therapy resistance and peritoneal metastasis.

EXPERIMENTAL DESIGN

We derived nine PDO and PDX models from patients with colorectal SRCC. Detailed histopathologic characterization confirmed the fidelity of these models to the original tumors. Drug sensitivity assays were conducted in vitro and in vivo to assess the therapeutic efficacy and impact on peritoneal metastasis. An RNA sequencing analysis was performed to identify critical pathways contributing to therapy resistance and metastatic progression.

RESULTS

We successfully developed and characterized PDO and PDX models from nine patients with SRCC. The SRCC PDO and PDX models exhibited histopathologic features consistent with those of the original tumors, including high mucin content and eccentric nuclei. They demonstrated increased sensitivity to FOLFIRI combined with paclitaxel or vincristine, reducing peritoneal metastasis. RNA sequencing analysis revealed the upregulation of autophagy genes in SRCC. Treatment with chloroquine alone resulted in decreased tumor growth and peritoneal metastasis.

CONCLUSIONS

Our study establishes PDO and PDX models as robust platforms for studying SRCC and identifying potential therapeutic strategies. Combining FOLFIRI with paclitaxel/vincristine or chloroquine alone inhibits tumor growth and prevents peritoneal metastasis, showing promise for clinical translation. These findings suggest that combining FOLFIRI with intraperitoneal paclitaxel warrants further investigation in phase I clinical trials for patients with SRCC.

Inhibiting de novo lipogenesis identifies a therapeutic vulnerability in therapy-resistant colorectal cancer

A significant clinical challenge in patients with colorectal cancer (CRC), which adversely impacts patient survival, is the development of therapy resistance leading to a relapse. Therapy resistance and relapse in CRC is associated with the formation of lipid droplets (LD) by stimulating de novo lipogenesis (DNL). However, the molecular mechanisms underlying the increase in DNL and the susceptibility to DNL-targeted therapies remain unclear. Our study demonstrates that colorectal drug-tolerant persister cells (DTPs) over-express Lipin1 (LPIN1), which facilitates the sequestration of free fatty acids into LDs. The increased expression is mediated by the ETS1-PTPN1-c-Src-CEBPβ pathway. Blocking the conversion of free fatty acids into LDs by treatment with statins or inhibiting lipin1 expression disrupts lipid homeostasis, leading to lipotoxicity and ferroptotic cell death in both DTPs and patient-derived organoids (PDOs) in vitro. Ferroptosis inhibitors or N-acetylcysteine (NAC) can alleviate lipid ROS and cell death resulting from lipin1 inhibition. This strategy also significantly reduces tumor growth in CRC DTP mouse xenograft and patient-derived xenograft (PDX) models. Our findings highlight a new metabolic vulnerability in CRC DTPs, PDO, and PDX models and provide a framework for the rational repurposing of statins. Targeting the phosphatidic acid (PA) to diacylglycerol (DAG) conversion to prevent lipid droplet formation could be an effective therapeutic approach for therapy-resistant CRC.

Mucinous Rectal Adenocarcinoma-Challenges in Magnetic Resonance Imaging Interpretation

ABSTRACT

Mucinous rectal cancer (MRC) is defined by the World Health Organization as an adenocarcinoma with greater than 50% mucin content. Classic teaching suggests that it carries a poorer prognosis than conventional rectal adenocarcinoma. This poorer prognosis is thought to be related to mucin dissecting through tissue planes at a higher rate, thus increasing the stage of disease at presentation. Developments in immunotherapy have bridged much of this prognostic gap in recent years. Magnetic resonance imaging is the leading modality in assessing the locoregional spread of rectal cancer. Mucinous rectal cancer carries unique imaging challenges when using this modality. Much of the difficulty lies in the inherent increased T2-weighted signal of mucin on magnetic resonance imaging. This creates difficulty in differentiating mucin from the adjacent background fat, making the detection of both the primary disease process as well as the locoregional spread challenging. Computed tomography scan can act as a valuable companion modality as mucin tends to be more apparent in the background fat. After therapy, diagnostic challenges remain. Mucin is frequently present, and distinguishing cellular from acellular mucin can be difficult. In this article, we will discuss each of these challenges and present examples of such situations and strategies that can be used to overcome them.

The conundrum of total neoadjuvant therapy in rectal cancer

Total neoadjuvant therapy (TNT) has fast become the paradigm in the management of rectal cancer. The widespread adoption of this approach across the world, not only for locally advanced cancers but even for cancers that otherwise would not merit chemotherapy, leads both to an increase in treatment-related toxicity for patients and burdens the healthcare services of the country. It is important to tailor treatment to each patient based not only on the tumour but, even more importantly, on the patient's expectations and goals. The intent of treatment while prescribing TNT needs to be clear, understanding that not all patients are suitable for an organ preservation (watch and wait) approach and that the survival benefits of TNT are not as obvious as most proponents believe.

Pelvic exenterations combined with cytoreductions for T4 rectal cancers with peritoneal metastasis: a safety analysis

BACKGROUND

Pelvic exenterations and cytoreduction are individually morbid procedures with oncological validity. The combination of these simultaneously in patients with rectal cancers has not been evaluated. The present study aimed to assess the surgical and survival outcomes of the combined procedure.

METHODS

Retrospective, single-centre analysis of consecutive patients that underwent pelvic exenterations and cytoreductions for advanced or recurrent rectal cancers with peritoneal metastasis between 2013 and 2022. The primary outcome measure for safety was major complications (≥Grade IIIA). The threshold for considering the procedure unsafe was set at 50% for the upper confidence limit of major morbidity. Overall and recurrence-free survival were also assessed.

RESULTS

Thirty-nine patients underwent the combined procedure that included 24 total pelvic and 15 posterior pelvic exenterations. The median age of the cohort was 35 years, 18 (46.2%) had signet ring cell cancers, and eight patients (21%) had extraperitoneal disease as well. The median PCI was 4 and CC-0 was achieved in 38 patients (97.4%). Hyperthermic intraperitoneal chemotherapy was delivered in 15 patients, and four had placement of an intraperitoneal chemo port. Major complications were experienced by 7 patients (18%; 95% confidence interval: 7.5%-33.5%). Median recurrence-free and overall survivals were 9 and 17 months, respectively.

CONCLUSION

Combined pelvic exenterations and cytoreductions are safe operations in terms of morbidity. Survival, however, remains poor for this group of patients despite aggressive surgery.

Spatial Epidemiology of Signet-ring Cell Colorectal Cancer in India

BACKGROUND

Signet-ring cell colorectal carcinoma (SRCC) is an extremely aggressive yet uncommon histologic subtype of colorectal cancer (CRC) with an unknown etiology. There is a stark difference in the prevalence of signet cancers between Western countries and the Indian subcontinent; however, India itself is a vast and diverse country with variable cancer incidence.

OBJECTIVE

To study the spatial epidemiology of SRCC in India for identifying regions with high prevalence.

METHODS

This retrospective study included all patients diagnosed with colorectal adenocarcinoma at Tata Memorial Hospital, the largest colorectal cancer referral unit in India, between January 2020 and December 2022. Geocoding based on the location of the residence was done to map the incidences. Comparisons were performed between the proportion of signet cell and non-signet colorectal cancers.

RESULTS

A total of 4100 patients with colon or rectal adenocarcinomas were included, of which signet cell histology was found in 624 (15%) patients. SRCC accounted for the highest proportions of CRCs in the Central (19%) and Northern (19%) regions, and the lowest in the North-Eastern (10%) and Western (12%) regions of India (P < 0.001), with non-overlapping confidence intervals. Compared with patients with non-signet CRCs, those with SRCC more commonly had colon cancers (22% vs. 17%; P = 0.003) and belonged to a lower socioeconomic background (67% vs. 59%; P < 0.001).

CONCLUSIONS

This study found that SRCCs accounted for a significant proportion of CRC cases in India, but there was no substantial disparity in distribution across regions.

Impact of consolidation chemotherapy in poor responders to neoadjuvant radiation therapy: magnetic resonance imaging-based clinical-radiological correlation in high-risk rectal cancers

PURPOSE

The current study was conducted to examine the role of consolidation chemotherapy after neoadjuvant radiation therapy (NART) in decreasing the involvement of the mesorectal fascia (MRF) in high-risk locally advanced rectal cancers (LARCs).

METHODS

In total, 46 patients who received consolidation chemotherapy after NART due to persistent MRF involvement were identified from a database. A team of 2 radiologists, blinded to the clinical data, studied sequential magnetic resonance imaging (MRI) scans to assess the tumor response and then predict a surgical plan. This prediction was then correlated with the actual procedure conducted as well as histopathological details to assess the impact of consolidation chemotherapy.

RESULTS

The comparison of MRI-based parameters of sequential images showed significant downstaging of T2 signal intensity, tumor height, MRF involvement, diffusion restriction, and N category between sequential MRIs (P < 0.05). However, clinically relevant downstaging (standardized mean difference, > 0.3) was observed for only T2 signal intensity and diffusion restriction on diffusion-weighted imaging. No clinically relevant changes occurred in the remaining parameters; thus, no change was noted in the extent of surgery predicted by MRI. Weak agreement (Cohen κ coefficient, 0.375) and correlation (Spearman rank coefficient, 0.231) were found between MRI-predicted surgery and the actual procedure performed. The comparison of MRI-based and pathological tumor response grading also showed a poor correlation.

CONCLUSION

Evidence is lacking regarding the use of consolidation chemotherapy in reducing MRF involvement in LARCs. The benefit of additional chemotherapy after NART in decreasing the extent of planned surgery by reducing margin involvement requires prospective research.

What are the preoperative predictors of a futile pelvic exenteration in rectal cancers?

INTRODUCTION

Early recurrences and deaths after a morbid procedure like pelvic exenteration are devastating events. The present study aimed at determining the incidence and predictors of futile pelvic exenterations.

METHODS

Consecutive pelvic exenterations for advanced and recurrent rectal adenocarcinomas operated between January 2013 and January 2021 were included with a minimum of six months follow-up. Futility of exenteration was defined as recurrence or death within six months of operation. Multivariate logistic regression was used to define predictors of futility.

RESULTS

Two-hundred eighty-five patients were included and 61 patients (21.4%) had a futile resection. Poorly differentiated (or signet) histology, presence of lateral pelvic nodes, M1 disease, and the need for pelvic bone resections predicted a futile resection. The probability of futility was 10%, 20%, 35-40%, 55-60%, and >75% when none, one, two, three, and all four of the predictors were present. The model was able to correctly predict futility in 70% of the cases suggesting moderate discrimination, and showed good calibration.

CONCLUSIONS

Futile pelvic exenterations were observed in one-fifth of patients. Four strong predictors of futility were identified. The risk of early failures was additive when combination of these adverse features was present, and can be used for patient selection and prognostication.

Minimally invasive surgery for maximally invasive tumors: pelvic exenterations for rectal cancers

Purpose

Trials comparing minimally invasive rectal surgery have uniformly excluded T4 tumors. The present study aimed to determine the safety of minimally invasive surgery (MIS) for locally-advanced rectal cancers requiring pelvic exenterations based on benchmarked outcomes from the international PelvEx database.

Methods

Consecutive patients of T4 rectal cancers with urogenital organ invasion that underwent MIS exenterations between November 2015 and June 2022 were analyzed from a single center. A safety threshold was set at 20% for R1 resections and 40% for major complications (≥grade IIIA) for the upper limit of the 95% confidence interval (CI).

Results

The study included 124 MIS exenterations. A majority had a total pelvic exenteration (74 patients, 59.7%). Laparoscopic surgery was performed in 95 (76.6%) and 29 (23.4%) had the robotic operation. Major complications were observed in 35 patients (28.2%; 95% CI, 20.5%-37.0%). R1 resections were found pathologically in nine patients (7.3%; 95% CI, 3.4%-13.4%). The set safety thresholds were not crossed. At a median follow-up of 15 months, 44 patients (35.5%) recurred with 8.1% local recurrence rate. The 2-year overall and disease-free survivals were 85.2% and 53.7%, respectively.

Conclusion

MIS exenterations for locally-advanced rectal cancers demonstrated acceptable morbidity and safety in term of R0 resections at experienced centers. Longer follow-up is required to demonstrate cancer survival outcomes.

Bowel Functional Outcomes After Long-Course or Short-Course Radiation for Advanced Rectal Cancers: A Propensity-Matched Analysis

BACKGROUND

Despite short-course radiation and chemotherapy gaining popularity because of similar or better oncological outcomes, functional outcomes relative to long-course radiation have not been evaluated.

OBJECTIVE

To compare bowel function outcomes after long-course or short-course radiation and delayed operation for advanced rectal cancers.

DESIGN

Propensity-matched analysis.

SETTINGS

This study was conducted at a single tertiary cancer center. Patients were operated on between 2014 and 2020.

PATIENTS

The study included patients with locally advanced, nonmetastatic, mid, and low rectal cancers who underwent low anterior resection with stapled anastomosis and diverting ostomy. Extended or beyond total mesorectal excisions and lateral node dissections were excluded.

INTERVENTIONS

Long-course radiation delivered as a radiation dose of 50 Gy in 25 fractions or short-course radiation (5 Gy in 5 fractions) and delayed surgery after 4 to 6 weeks with or without chemotherapy.

MAIN OUTCOME MEASURES

One-time assessment of low anterior resections syndrome and Wexner incontinence scores at least 6 months after stoma reversal.

RESULTS

After matching 124 patients in the 1:2 ratio between short- and long-course radiations, 93 patients were included for analysis. Any low anterior resection syndrome was found in 90.3% of short-course patients compared to 54.8% after long-course radiation (p < 0.001). Major incontinence was detected in 6.5% after short-course radiation as opposed to 8.1% of patients after long-course radiation (p = 0.781). On multivariate logistic regression, short-course radiation predicted the development of any low anterior resection syndrome with an OR of 4.4.

LIMITATIONS

Selection and misclassification biases from retrospective recruitment.

CONCLUSIONS

For patients with locally advanced, nonmetastatic, mid, and low rectal cancers who underwent preoperative radiation followed by stapled low anterior resection, short-course radiation had higher probability of developing low anterior resection syndrome than long-course radiation. See Video Abstract at http://links.lww.com/DCR/C37.

RESULTADOS DE LA FUNCIN INTESTINAL DESPUS DE LA RADIACIN DE CICLO LARGO O CORTO EN CNCER DE RECTO AVANZADO UN ANLISIS EMPAREJADO DE PROPENSIN

ANTECEDENTES:A pesar de que la radiación de corta duración y la quimioterapia están ganando popularidad debido a resultados oncológicos similares o mejores, los resultados funcionales en relación con la radiación de larga duración no han sido evaluado.OBJETIVO:Comparar resultados de la función intestinal después de la radiación de ciclo largo o corto y cirugía diferida para los en cáncer de recto avanzado.DISEÑO:Análisis emparejado de propensión.ENTORNO CLINICO:Centro único de cáncer terciario. Pacientes operados entre 2014 y 2020.PACIENTES:Cánceres de recto medio y bajo localmente avanzados, no metastásicos, que se sometieron a resección anterior baja con anastomosis grapada y ostomía de derivación. Se excluyeron las escisiones total de mesorecto extendidas o más allá del plano y las disecciones de los ganglios laterales.INTERVENCIONES:Radiación de ciclo largo administrada como 50 Gy en 25 fracciones o radiación de ciclo corto (5 Gy en 5 fracciones) y cirugía diferida después de 4 a 6 semanas con o sin quimioterapia.PRINCIPALES MEDIDAS DE RESULTADO:Evaluación única del síndrome de reseccion anterior baja y escala de Wexner de incontinencia al menos seis meses después de la restitución del tránsito intestinal.RESULTADOS:Después de emparejar 124 pacientes en la proporción 1:2 entre radiación de ciclo corto y largo, se incluyeron 93 pacientes para el análisis. Se encontró cualquier síndrome de resección anterior baja en el 90,3% de los pacientes de ciclo corto en comparación con el 54,8% después de la radiación de ciclo largo (p < 0,001). Se detectó incontinencia grave en el 6,5% después de un tratamiento de corta duración frente al 8,1% de los pacientes que recibieron un tratamiento de radiación de larga duración (p = 0,781). En la regresión logística multivariable, la radiación de corta duración predijo el desarrollo de cualquier síndrome de resección anterior baja con una probabilidad de 4,4.LIMITACIONES:Sesgos de selección y clasificación errónea de reclutamiento retrospectivo.CONCLUSIONES:Para los cánceres de recto medio e inferior localmente avanzados, no metastásicos, que se sometieron a radiación preoperatoria seguida de resección anterior baja con grapas, curso corto tuvo una mayor probabilidad de desarrollar síndrome de resección anterior baja en comparación con radiación de curso largo. Consulte Video Resumen en http://links.lww.com/DCR/C37. (Traducción- Dr. Francisco M. Abarca-Rendon).

Early-onset non-metastatic colon cancers do not portend worse prognosis - implications for adjuvant chemotherapy

BACKGROUND

Early-onset colon cancers are increasing and the independent influence of age on prognosis and therapeutic efficacy of adjuvant therapy is unclear. The primary aim of the present study was to determine if young age was an independent prognostic factor for survival. Secondarily, age would be used in the context of known factors that predict benefit with adjuvant chemotherapy in stages II and III.

METHODS

Retrospective, single centre study of operated, non-metastatic colon cancer (> 15 cm from anal verge) without pre-operative therapy. Early onset cancers were defined as age ≤ 45 years. Primary endpoint was disease-free survival (DFS).

RESULTS

Six-hundred thirty-three patients were included with 206 (32.5%) early-onset cancers. With a median follow-up of 48 months, 5-year DFS was 79.5% and 76.2% for early and late-onset cancers, respectively (p - 0.585). In multivariate analysis, only tumour sidedness, family history, T4 stage, node positivity and microsatellite instability status influenced DFS and not the age of onset (HR - 0.969; 95% - 0.63-1.49). These results were consistent with different models and with stage-wise distribution.

CONCLUSIONS

Early-onset colon cancers treated with curative intent had survivals similar to older cohorts. Age was not an independent prognostic factor for recurrences. Age did not influence disease-free survival when stage-wise predictive variables for therapeutic benefit with adjuvant chemotherapy were considered.

Laparoscopic ovarian transposition in teenage and young women with locally advanced rectal cancer: Respite amidst cancer chaos

AIM

Ovarian transposition is an established surgical technique to salvage ovaries in premenopausal women requiring pelvic radiation. The success rate of ovarian transposition varies widely depending on the route, technique of surgery, type of cancer and treatment. Here, we aimed to analyse the effectiveness of laparoscopic ovarian transposition (LOT) in teenage and young women prior to pelvic radiation in locally advanced rectal cancers (LARC).

METHODS

Patients who underwent LOT for rectal cancers were retrieved from a prospectively maintained database from June 2013-September 2019. Disease characteristics, return of menstrual function and oncological outcomes were analysed.

RESULTS

A total of 46 women with a mean age of 25.2 years who underwent LOT at the cancer centre were included in the study. Seventy percent were nulliparous. All patients were fit for discharge by 24 h. Mean time to start radiation was 19.6 days (range 3-47 days). Median follow-up of patients was 42 months. A total of 41 patients were assessable for ovarian function, 65.5% had resumption of menses. Median ovarian survival was 79 months and 5-year ovarian survival was 54%. Median overall survival from rectal cancer was 51 months.

CONCLUSION

Laparoscopic ovarian transposition is a safe and effective technique of ovarian protection from the gonadotoxic effects of pelvic radiation in LARC. It does not delay primary treatment and does not compromise oncological outcomes. Long-term follow-up is required to evaluate fertility and quality of life.

Learning curve analysis for lateral pelvic lymph node dissection in rectal cancers - Outcomes improve with experience

INTRODUCTION

Lateral pelvic lymph node dissection (LPLND) is a technically challenging procedure and its learning curve has not been analysed against an oncologically relevant outcome. The purpose of the study was to determine the learning curve for LPLND in rectal cancers using nodal retrieval as performance measure.

METHODS

Consecutive LPLND for rectal adenocarcinomas from a single institution were retrospectively analysed. Cumulative sum (CUSUM) control charts were used to detect difference in performance with respect to lymph node yield. Negative binomial regression was used to determine factors influencing nodal harvest using Incidence Risk Ratios (IRR). Separate CUSUM curves were generated for open and minimally invasive surgeries (MIS).

RESULTS

One-hundred and twenty patients were included and all received preoperative radiation. MIS was used in 53.3%. Median lymph node yield was 6 with 20% nodal positivity. Increasing experience (IRR - 1.196) and MIS (IRR - 1.586) were the only factors that influenced nodal harvest. CUSUM charts revealed that learning curve was achieved after the 83rd case overall and after the 19 operations in MIS. There was a 20% increase in nodal yield after every 30 MIS LPLND performed.

CONCLUSIONS

Learning curve for LPLND is relatively long and only increasing experience and minimally invasive operations increased nodal yield.

Prospective study to assess the role of FDG PET/CT in detecting systemic metastatic spread in rectal cancers with lateral pelvic lymph nodes

INTRODUCTION

The utility of positron emission tomography (PET) in detecting additional M1 patients over conventional staging modalities is not known in rectal cancer patients with enlarged lateral pelvic nodes.

METHODS

Prospective, single center, single-arm interventional study of consecutive rectal cancer patients that had baseline lateral pelvic nodes on MRI (>10 mm) between February 2017 to December 2018. Such patients underwent PET after confirming non-metastatic status on CT of thorax and abdomen. Primary outcome measure was additional M1 sites detected on PET. A 10% distant metastasis rate was expected with 80% confidence interval (CI) set at 5% as the lower limit.

RESULTS

44 patients were included and the concordance between MRI and PET in detection of lateral nodes was 97.7% (43 patients). Additional sites of metastasis were detected in 5 patients (11.36%; 80% CI - 5.63%-20.6%), and there was a change in treatment plan in 7 (15.9%). The number needed to treat (NNT) for PET scans to detect additional metastatic sites and change treatment were 9 and 6 respectively. There was a change in treatment intent (curative to palliative) in 2 patients (4.5%, NNT - 22).

CONCLUSION

In rectal cancer patients with LPLN, the use of FDG-PET-CT over conventional staging studies led to the detection of additional extra-pelvic metastasis in 11.4% and changed the treatment plan in 15.9%. This met the pre-defined threshold to endorse the use of PET-CT in patients that match the study characteristics.