International consensus recommendations on key outcome measures for organ preservation after (chemo)radiotherapy in patients with rectal cancer

Locally advanced rectal cancer in a young adult affected with dyskeratosis congenita (Zinsser-Cole-Engman syndrome): a case report

BACKGROUND

Dyskeratosis congenita (DKC), also known as Zinsser-Cole-Engman syndrome, is a progressive genetic disease with a triad of reticulate skin pigmentation, nail dystrophy, and leukoplakia. Approximately 8-10% of patients with DKC develop malignancies, and cases of colorectal cancer with DKC in young people have been reported previously.

CASE PRESENTATION

A 25-year-old man with DKC since approximately 10 years of age developed fever and lower abdominal discomfort. Diagnostic imaging revealed locally advanced rectal cancer with lymph node metastasis, direct invasion of the prostate, and pelvic abscess due to tumor microperforation (cT4bN2M0 cStage IIIC). Biopsy showed well to moderately differentiated ductal adenocarcinoma. Genetic testing was negative for RAS and BRAF gene mutations, and microsatellite instability (MSI) testing was also negative. After sigmoid colostomy, the patient was treated with total neoadjuvant therapy (TNT) with systemic chemotherapy (six courses of FOLFOX + panitumumab) followed by chemoradiation therapy (50.4 Gy with capecitabine). After TNT, the primary tumor and metastatic lymph nodes shrank. According to the findings of colonoscopy and magnetic resonance image (MRI), we diagnosed near complete response (near-CR) and decided to follow the patient without surgery by every 3 months re-evaluation. However, 5 months after TNT, tumor regrowth was detected on colonoscopy and imaging, and the patient underwent total pelvic exenteration. He developed paralytic ileus as a postoperative complication, and was discharged on the 38th postoperative day. Pathological examination revealed a residual tumor with invasion of the periprostatic tissue. There was no metastasis in the pararectal and lateral pelvic lymph nodes, but one extramural non-contiguous cancerous extension (tumor deposit) was observed (ypT4bN1cM0 ypStage IIIC). The patient has been free of recurrence for one year after surgery.

CONCLUSIONS

DKC often develops into various tumors in the digestive system at an early age; therefore, appropriate surveillance may be required. In addition, considering that cancers in patients with DKC occur at a young age, fertility preservation and survivorship are also important, and adequate explanations and care should be provided to patients before and after treatment.

Oncological risks associated with the planned watch-and-wait strategy using total neoadjuvant treatment for rectal cancer: A narrative review

Overall survival benefit of total neoadjuvant treatment (TNT) remains unconfirmed. Thus, in our opinion, the main rationale for using TNT is a planned watch-and-wait (w&w) strategy to improve patients' long-term quality of life through organ preservation. The OPRA randomized trial, which examined a planned w&w strategy using TNT, showed a higher organ preservation rate but also a higher regrowth rate compared to studies on the opportunistic w&w strategy. Higher rates of complete clinical response with TNT did not improve disease-free survival compared to historical controls. Therefore, the gain in organ-sparing capability might not be balanced by the increased oncological risk. The ultimate local failure rate in the intention-to-treat analysis of the OPRA trial was 13% for induction chemotherapy and 16% for consolidation chemotherapy, which seems higher than expected compared to 8% in a meta-analysis of w&w studies or 12% after TNT and surgery in the PRODIGE-23 and RAPIDO trials, which enrolled patients with more advanced cancers than the OPRA trial. Other studies also suggest worse local control when surgery is delayed for radio-chemoresistant cancers. Our review questions the safety of the planned w&w strategy using TNT in unselected patients. To reduce the oncological risk while maintaining high organ preservation rates, we suggest that the planned w&w strategy using TNT requires a two-tier patient selection process: before treatment and after tumor response assessment at the midpoint of consolidation chemotherapy. These robust selections should identify patients who are unlikely to achieve organ preservation with TNT and would be better managed by preoperative chemoradiotherapy (without consolidation chemotherapy) and surgery, or by discontinuing consolidation chemotherapy and proceeding directly to surgery.

Management of Locally Advanced Rectal Cancer: ASCO Guideline

PURPOSE

To provide evidence-based guidance for clinicians who treat patients with locally advanced rectal cancer.

METHODS

A systematic review of the literature published from 2013 to 2023 was conducted to identify relevant systematic reviews, phase II and III randomized controlled trials (RCTs), and observational studies where applicable.

RESULTS

Twelve RCTs, two systematic reviews, and one nonrandomized study met the inclusion criteria for this systematic review. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations.

RECOMMENDATIONS

Following assessment with magnetic resonance imaging, for patients with microsatellite stable or proficient mismatch repair locally advanced rectal cancer, total neoadjuvant therapy (TNT; ie chemoradiation [CRT] and chemotherapy) should be offered as initial treatment for patients with tumors located in the lower rectum and/or patients who are at higher risk for local and/or distant metastases. Patients without higher-risk factors may discuss chemotherapy with selective CRT depending on extent of response, TNT, or neoadjuvant long-course CRT or short-course radiation. For patients who are candidates for TNT, the preferred timing for chemotherapy is after radiation, and neoadjuvant long-course CRT is preferred over short-course radiation therapy (RT), however short-course RT may also be a viable treatment option depending on circumstances. Nonoperative management may be discussed as an alternative to total mesorectal excision for patients who have a clinical complete response to neoadjuvant therapy. For patients whose tumors are microsatellite instability-high or mismatch repair deficient, immunotherapy is recommended.Additional information is available at http://www.asco.org/gastrointestinal-cancer-guidelines.

International Expert Consensus on Semantics of Multimodal Esophageal Cancer Treatment: Delphi Study

BACKGROUND

Recent developments in esophageal cancer treatment, including studies exploring active surveillance following chemoradiotherapy, have led to a need for clear terminology and definitions regarding different multimodal treatment options.

OBJECTIVE

The aim of this study was to reach worldwide consensus on the definitions and semantics of multimodal esophageal cancer treatment.

METHODS

In total, 72 experts working in the field of multimodal esophageal cancer treatment were invited to participate in this Delphi study. The study comprised three Delphi surveys sent out by email and one online meeting. Input for the Delphi survey consisted of terminology obtained from a systematic literature search. Participants were asked to respond to open questions and to indicate whether they agreed or disagreed with different statements. Consensus was reached when there was ≥75% agreement among respondents.

RESULTS

Forty-nine of 72 invited experts (68.1%) participated in the first online Delphi survey, 45 (62.5%) in the second survey, 21 (46.7%) of 45 in the online meeting, and 39 (86.7%) of 45 in the final survey. Consensus on neoadjuvant and definitive chemoradiotherapy with or without surgery was reached for 27 of 31 items (87%). No consensus was reached on follow-up after treatment with definitive chemoradiotherapy.

CONCLUSION(S)

Consensus was reached on most statements regarding terminology and definitions of multimodal esophageal cancer treatment. Implementing uniform criteria facilitates comparison of studies and promotes international research collaborations.

Arterial Mucosal Linear Enhancement at Contrast-enhanced MRI to Exclude Residual Tumor after Neoadjuvant Chemotherapy and Radiation Therapy for Rectal Cancer

Background A watch-and-wait regimen for locally advanced rectal cancer after neoadjuvant chemotherapy and radiation therapy (NCRT) relies on identifying complete tumor response. However, the concordance between a complete response at combined T2-weighted and diffusion-weighted MRI (T2DWI) and pathologic complete response (pCR; ie, ypT0N0) in the tumor is unsatisfactory. Purpose To assess whether identification of mucosal linear enhancement (MLE) at arterial-phase contrast-enhanced (CE) T1-weighted MRI is associated with ypT0 status in patients with locally advanced rectal cancer after NCRT and to evaluate whether combining MLE at CE T1-weighted MRI and negative lymph node metastasis (LNM) at T2DWI can improve identification of pCR. Materials and Methods This retrospective study included patients with locally advanced rectal cancer who underwent total mesorectal excision after NCRT between July 2020 and July 2023 at a tertiary referral academic center. Restaging MRI included T2DWI and arterial-phase CE T1-weighted MRI for primary tumor assessment and T2DWI for evaluation of LNM status. Imaging features associated with ypT0 status were identified at multivariable regression analysis. Results In total, 239 patients (mean age, 58 years ± 12 [SD]; 180 male patients) were assessed. MLE was more common in the ypT0 group than in the ypT1-4 group after NCRT (73% vs 4%, respectively; P < .001). MLE was associated with higher odds of ypT0 status in an adjusted analysis (odds ratio, 137; 95% CI: 25, 767; P < .001). The combination of MLE and negative LNM status achieved an area under the receiver operating characteristic curve of 0.84 (95% CI: 0.79, 0.88) for pCR. Conclusion MLE at CE MRI was associated with higher odds of complete tumor response. Combining MLE and negative LNM status showed good performance for identifying complete tumor response and may exclude residual tumors after NCRT in patients with locally advanced rectal cancer. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Schoellnast in this issue.

Outcomes associated with total neoadjuvant therapy with non-operative intent for rectal adenocarcinoma

Purpose/objectives

To evaluate rates of clinical complete response (cCR), surgery-free survival, permanent ostomy-free survival, and factors associated with these outcomes in patients treated with total neoadjuvant therapy (TNT) with intent for non-operative management of rectal adenocarcinoma.

Methods

A retrospective review was conducted of patients treated with TNT for stage II-IV rectal adenocarcinoma (n=45) at our institution between 2013 - 2022 with curative intent. All patients received radiation with concurrent capecitabine and additional chemotherapy, either prior to or following chemoradiation (CRT), with intent for non-operative management. Response rates were determined based on post-treatment MRI and endoscopy. Kaplan-Meier method was utilized to estimate the 1- and 2-year surgery- and permanent ostomy-free survivals. Cox regression was used to evaluate associations between surgery- and permanent ostomy-free survivals and various factors of interest, including patient and tumor characteristics and clinical response. Chi-squared analysis compared rates of cCR and surgery by sequence of TNT modality and cell count ratios.

Results

Of the 45 patients treated with TNT, most patients had low-lying rectal tumors with a median distance of 4.1 cm from the anal verge (range, 0.0 - 12.0). Overall, 64.4% (n=29) achieved cCR after TNT. 13 patients (28.9%) underwent surgical resection following TNT, 12 of whom had incomplete response and one who elected to undergo surgery after reaching cCR. At median follow up of 32.0 months (range, 7.1 - 86.1), 22.2% (n=10) of patients had a permanent colostomy, with only 2 of these completed for tumor regrowth after cCR. At one and two years, respectively, surgery-free survival was 77.3% and 66.2%, and permanent ostomy-free survival was 90.9% and 78.2%. Rates of cCR were higher in patients who received CRT first compared to those who received chemotherapy first (72.2% vs. 33.3%, p=0.029) and rates of surgery were also lower in patients who received CRT first compared to those who received chemotherapy first (19.4% vs. 66.7%, p=0.005). On Cox regression model, cCR on 6 month post-CRT endoscopy was associated with surgery-free survival (p=0.006) and permanent ostomy-free survival (p=0.033). Clinical response at earlier follow up points did not predict surgery- nor permanent ostomy-free survival.

Conclusion

These results support evidence that TNT may be a non-surgical option for select patients with rectal adenocarcinoma who desire organ preservation. In this investigation at a single institution, the treatment response on 6-month post-CRT endoscopy was the best predictor of surgery- and permanent ostomy-free survival, which are outcomes that are important to patient quality of life. CRT followed by consolidation chemotherapy was associated with higher rates of cCR and lower rates of surgery compared to those treated with induction chemotherapy.

Gold Nanocluster: A Photoelectric Converter for X-Ray-Activated Chemotherapy

Despite the promise of activatable chemotherapy, the development of a spatiotemporally controllable strategy for prodrug activation in deep tissues remains challenging. Herein, a proof-of-concept is proposed for a gold nanocluster-based strategy that utilizes X-ray irradiation to trigger the liberation of platinum (Pt)-based prodrug conjugates, thus enabling radiotherapy-directed chemotherapy. Mechanistically, the irradiated activation of prodrugs is achieved through direct photoelectron transfer from the excited-state gold nanoclusters to the Pt(IV) center, resulting in the release of cytotoxic Pt(II) agents. Compared to the traditional combination of chemotherapy and radiotherapy, this radiotherapy-directed chemotherapy strategy offers superior antitumor efficacy and safety benefits through spatiotemporal synergy at the tumor site. Additionally, this strategy elicits robust immunogenic cell death and yields profound outcomes for combined immunotherapy of breast cancer. This versatile strategy is ushering in a new era of radiation-mediated chemistry for controlled drug delivery and the precise regulation of biological processes.

Gut microbiome model predicts response to neoadjuvant immunotherapy plus chemoradiotherapy in rectal cancer

BACKGROUND

Accurate evaluation of the response to preoperative treatment enables the provision of a more appropriate personalized therapeutic schedule for locally advanced rectal cancer (LARC), which remains an enormous challenge, especially neoadjuvant immunotherapy plus chemoradiotherapy (nICRT).

METHODS

This prospective, multicenter cohort study enrolled patients with LARC from 6 centers who received nICRT. The dynamic variation in the gut microbiome during nICRT was evaluated. A species-level gut microbiome prediction (SPEED) model was developed and validated to predict the pathological complete response (pCR) to nICRT.

FINDINGS

A total of 50 patients were enrolled, 75 fecal samples were collected from 33 patients at different time points, and the pCR rate reached 42.4% (14/33). Lactobacillus and Eubacterium were observed to increase after nICRT. Additionally, significant differences in the gut microbiome were observed between responders and non-responders at baseline. Significantly higher abundances of Lachnospiraceaebacterium and Blautiawexlerae were found in responders, while Bacteroides, Prevotella, and Porphyromonas were found in non-responders. The SPEED model showcased a superior predictive performance with areas under the curve of 98.80% (95% confidence interval [CI]: 95.67%-100%) in the training cohort and 77.78% (95% CI: 65.42%-88.29%) in the validation cohort.

CONCLUSIONS

Programmed death 1 (PD-1) blockade plus concurrent long-course CRT showed a favorable pCR rate and is well tolerated in microsatellite-stable (MSS)/mismatch repair-proficient (pMMR) patients with LARC. The SPEED model can be used to predict the pCR to nICRT based on the baseline gut microbiome with high robustness and accuracy, thereby assisting clinical physicians in providing individualized management for patients with LARC.

FUNDING

This research was funded by the China National Natural Science Foundation (82202884).

Colorectal cancer

Despite decreased incidence rates in average-age onset patients in high-income economies, colorectal cancer is the third most diagnosed cancer in the world, with increasing rates in emerging economies. Furthermore, early onset colorectal cancer (age ≤50 years) is of increasing concern globally. Over the past decade, research advances have increased biological knowledge, treatment options, and overall survival rates. The increase in life expectancy is attributed to an increase in effective systemic therapy, improved treatment selection, and expanded locoregional surgical options. Ongoing developments are focused on the role of sphincter preservation, precision oncology for molecular alterations, use of circulating tumour DNA, analysis of the gut microbiome, as well as the role of locoregional strategies for colorectal cancer liver metastases. This overview is to provide a general multidisciplinary perspective of clinical advances in colorectal cancer.

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

BACKGROUND

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.

PATIENTS AND METHODS

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).

RESULTS

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.

CONCLUSIONS

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.

Chemoradiation, Consolidation Chemotherapy, and Watch and Wait for Early Rectal Cancer

As watch and wait has become an attractive management alternative among patients with rectal cancer who achieve a clinical complete response to neoadjuvant chemoradiation, the focus of organ preservation has now shifted toward the use of this approach in patients with early rectal cancer. These patients would otherwise be treated without the use of neoadjuvant therapy for oncological reasons. The sole purpose of any neoadjuvant treatment here would be the achievement of a complete clinical response in an attempt to avoid total mesorectal excision. This has become particularly interesting after the incorporation of total neoadjuvant therapy regimens. These regimens have resulted in significantly higher rates of complete tumor regression and therefore become an interesting alternative among early rectal cancer patients where organ preservation is desired. The present review provides an overview of the currently available evidence and the preliminary experience with this rather controversial approach.

The multidisciplinary management of locally advanced rectal cancer

INTRODUCTION

The classic paradigm for the management of locally advanced rectal cancer (LARC) consists of (chemo)radiotherapy (C)RT), total mesorectal excision, and adjuvant chemotherapy (CHT). At present, due to the high rate of distant metastasis (up to 30%), the total neoadjuvant therapy (TNT) with the administration of systemic CHT in the neoadjuvant setting has gained acceptance as standard of care.Our aim is to critically review the current literature on LARC management and summarize the different approaches recently proposed to improve clinical outcomes. It represents a starting step to develop an effective strategy that ultimately could harmonize the standard of care in daily clinical practice.

AREAS COVERED

Studies reporting the impact of TNT approaches were deemed eligible. De-escalation strategies, including non-operative management (NOM) after TNT, as well as RT omission or systemic therapy alone, were also investigated.

EXPERT OPINION

The year 2020 has seen promising new data from randomized phase III trials in the field of LARC management. Nowadays, TNT strategy has been accepted as the primary treatment for LARC. The role of de-escalation strategies is still unknown. The goal is to achieve better survival outcomes with improving quality of life. Only selected patients are likely to benefit from NOM or immunotherapy alone.

The effect of Inc parameter on VMAT radiotherapy plans quality for rectal cancer using Monaco TPS

BACKGROUND

To investigate the effect of the Increment of gantry angle (Inc) parameter setting of the Monaco Treatment planning system (Monaco TPS) on the dosimetry and quality parameters of the volumetric modulated arc therapy (VMAT) program for rectal cancer.

METHODS

A retrospective analysis was conducted on 50 patients with rectal cancer who underwent intensity modulated radiation therapy using the Monaco TPS system from 2020 to 2021. Under the same optimization function configuration and other parameter settings, the Inc parameters in the VMAT radiotherapy plan were set to 10°, 20°, 30°, and 40°. The dose-volume histogram (DVH) was used to evaluate the dose distribution of the target area and the radiation dose of the organs at risk (OAR). The differences in the dosimetry of the planning target volume (PTV) and OAR, as well as the gamma pass rate (GPR) were compared.

RESULTS

In terms of target dose, D98, Dmin, HI, and conformity index (CI) of Inc10 group was significantly lower than those of Inc20, 30, and 40 groups (P < 0.05), and D2 of Inc10 group was significantly higher than that of Inc20 group (P = 0.009). We also found CI of Inc20 and 30 were significantly better than that of Inc40 (both P < 0.05). In terms of OAR dose, the study found that the Dmean, Dmin, V50%, V45%, and V40% for the bladder of the Inc10 group were lower than those of the other groups (all P < 0.05), the Dmean for femoral head of the Inc20 group was lower than that of the Inc30 group (P < 0.05), and Inc20 showed a better protective effect on the femoral head. The MUs tend to decrease as the Inc parameter setting is increased. The monitor unit (MU) in Inc10 group were significantly higher than those in Inc20, Inc30, and Inc40 groups, and the MU of Inc20 group was significantly higher than that of Inc40 group (both P < 0.05). We found that for the 3%/3 mm and 2%/2 mm standards, the GPRs of each plan were > 90%, which met clinical requirements.

CONCLUSIONS

Different settings of Inc parameters have varying degrees of impact on target dose, OAR dose, and machine MU. It is important for doctors to choose different Inc parameters according to different clinical needs.

Organ and function preservation in gastrointestinal cancer: Current and future perspectives on endoscopic ablation

The escalating prevalence of gastrointestinal cancers underscores the urgency for transformative approaches. Current treatment costs amount to billions of dollars annually, combined with the risks and comorbidities associated with invasive surgery. This highlights the importance of less invasive alternatives with organ preservation being a central aspect of the treatment paradigm. The current standard of care typically involves neoadjuvant systemic therapy followed by surgical resection. There is a growing interest in organ preservation approaches by way of minimizing extensive surgical resections. Endoscopic ablation has proven to be useful in precursor lesions, as well as in palliative cases of unresectable disease. More recently, there has been an increase in reports on the utility of adjunct endoscopic ablative techniques for downstaging disease as well as contributing to non-surgical complete clinical response. This expansive field within endoscopic oncology holds great potential for advancing patient care. By addressing challenges, fostering collaboration, and embracing technological advancements, the gastrointestinal cancer treatment paradigm can shift towards a more sustainable and patient-centric future emphasizing organ and function preservation. This editorial examines the evolving landscape of endoscopic ablation strategies, emphasizing their potential to improve patient outcomes. We briefly review current applications of endoscopic ablation in the esophagus, stomach, duodenum, pancreas, bile ducts, and colon.

Survival prognostic in different age groups of patients undergoing local versus radical excision for rectal cancer: a study based on the SEER database

Age significantly affects the prognosis of patients with rectal cancer after radical excision (RE), and local excision (LE) is an alternative surgical procedure to RE. To compare the survival prognosis in different age groups of LE versus RE for rectal cancer. Patients diagnosed with rectal adenocarcinoma treated by LE or RE from 2010 to 2017 were obtained from the SEER database. The primary outcomes are 5-year OS and CSS. A total of 11,170 patients were eventually included, and there were 490 patients in LE and RE groups, respectively, after 1:1 propensity score matching. The 5-year OS and CSS after LE were significantly better in < 50 years and 50-66 years groups than in > 66 years group (5-year OS: 95.70% vs 88.40% vs 67.00%, P < 0.001; 5-year CSS: 95.70% vs 96.30% vs 82.60%, P < 0.001). No statistical significance was found for the differences in 5-year OS and CSS between LE and RE in < 50, 50-66, and > 66 years group (P > 0.05). Multivariate analysis showed age > 66 years, poorly differentiated or undifferentiated (Grade III/IV), and tumor size 3 to 5 cm was independent risk factors for 5-year OS after LE; age > 66 years, perineural invasion, and tumor size 3 to 5 cm were the 5-year CSS independent risk factors for after LE. We found that the survival prognosis of younger rectal cancer patients treated with LE was significantly better than older (> 66 years) patients, and the survival prognosis of rectal cancer patients in the three age groups was similar between LE and RE.

Future direction of total neoadjuvant therapy for locally advanced rectal cancer

Despite therapeutic advancements, disease-free survival and overall survival of patients with locally advanced rectal cancer have not improved in most trials as a result of distant metastases. For treatment decision-making, both long-term oncologic outcomes and impact on quality-of-life indices should be considered (for example, bowel function). Total neoadjuvant therapy (TNT), comprised of chemotherapy and radiotherapy or chemoradiotherapy, is now a standard treatment approach in patients with features of high-risk disease to prevent local recurrence and distant metastases. In selected patients who have a clinical complete response, subsequent surgery might be avoided through non-operative management, but patients who do not respond to TNT have a poor prognosis. Refined molecular characterization might help to predict which patients would benefit from TNT and non-operative management. Specifically, integrated analysis of spatiotemporal multi-omics using artificial intelligence and machine learning is promising. Three prospective trials of TNT and non-operative management in Japan, the USA and Germany are collaborating to better understand drivers of response to TNT. Here, we address the future direction for TNT.

Watch & wait - Post neoadjuvant imaging for rectal cancer

Rectal cancer management has evolved over the past decade with the emergence of total neoadjuvant therapy (TNT). For select patients who achieve a clinical complete response following TNT, organ preservation by means of the watch-and-wait (WW) strategy is an increasingly adopted alternative that preserves rectal function and quality of life without compromising oncologic outcomes. Recently, published 5-year results from the OPRA trial demonstrated that organ preservation can be achieved in approximately half of patients managed with the WW strategy, with most local regrowth events occurring within two years. Considering the potential for local regrowth, the implementation of the WW strategy mandates rigorous clinical and radiographic surveillance. Magnetic resonance imaging (MRI) serves as the conventional imaging modality for local staging and surveillance of rectal cancer given its excellent soft-tissue resolution. This review will discuss the current evidence for the WW strategy and the role of restaging rectal MRI in determining patient eligibility for this strategy. Restaging rectal MRI acquisition parameters and treatment response assessment, including important factors to assess, pitfalls, and classification systems, will be discussed in the context of the WW strategy.

Interdisciplinary Spanish consensus on a watch-and-wait approach for rectal cancer

Watch-and-wait has emerged as a new strategy for the management of rectal cancer when a complete clinical response is achieved after neoadjuvant therapy. In an attempt to standardize this new clinical approach, initiated by the Spanish Cooperative Group for the Treatment of Digestive Tumors (TTD), and with the participation of the Spanish Association of Coloproctology (AECP), the Spanish Society of Pathology (SEAP), the Spanish Society of Gastrointestinal Endoscopy (SEED), the Spanish Society of Radiation Oncology (SEOR), and the Spanish Society of Medical Radiology (SERAM), we present herein a consensus on a watch-and-wait approach for the management of rectal cancer. We have focused on patient selection, the treatment schemes evaluated, the optimal timing for evaluating the clinical complete response, the oncologic outcomes after the implementation of this strategy, and a protocol for surveillance of these patients.

The ypT may better predict the efficacy of neoadjuvant chemoradiotherapy than tumor regression grade in locally advanced rectal cancer patients diagnosed ypT1-4N0

PURPOSE

This study aimed to assess the impact of ypT stage and tumor regression grade (TRG) on the long-term prognosis of patients with locally advanced rectal cancer (LARC) stage ypT1-4N0 after neoadjuvant chemoradiotherapy (NCRT).

METHODS

We retrospectively analyzed 585 patients with histologically diagnosed middle-low LARC (cT3-4 or cN + by pelvic MRI) from 2014 to 2019. All patients underwent NCRT, followed by total mesorectal excision. Disease-free survival (DFS) rates were compared among patients with different ypT stages and TRGs by Kaplan-Meier survival analysis. The chi-square test was used to analyze the relationship between clinicopathological or therapeutic factors and ypT stage.

RESULTS

The median follow-up was 35.8 months (range 2.8-71.8 months). The 3-year DFS was 79.5%. A better 3-year DFS was achieved in patients with a pathologic complete response (94.0% vs. 74.3%, p < 0.001) and those in the ypT0-2 (86.5% vs. 66.6%, p < 0.001), ypN0 (85.0% vs. 60.2%, p < 0.001), and TRG0 + 1 (83.1% vs. 73.0%, p = 0.004) subgroups. A total of 309 patients (52.8%) achieved stage ypT1-4N0 after surgery. Among these patients, the ypT1-2N0 subgroup achieved a significantly higher 3-year DFS than the ypT3-4N0 subgroup (85.4% vs. 72.8%, p = 0.018); in contrast, the 3-year DFS did not significantly differ between the TRG1 and TRG2 + 3 subgroups (79.9% vs. 81.1%, p = 0.833). In the ypT1-2N0 or ypT3-4N0 subgroup, different TRG had no significant effect on failure patterns.

CONCLUSIONS

For LARC patients with a ypT1-4N0 status after NCRT, ypT stage may be a more effective predictor of long-term prognosis than TRG.

Early Efficacy End Points in Neoadjuvant Rectal Cancer Trials: Surrogacy Revisited

Trial-level surrogacy is critical before early response endpoints are used to approve new therapies.

Liquid biopsy in colorectal cancer: Onward and upward

Colorectal cancer (CRC) remains a leading cause of cancer-related deaths worldwide. In recent years, liquid biopsy has emerged as one of the most interesting areas of research in oncology, leading to innovative trials and practical changes in all aspects of CRC management. RNAs and cell free DNA (cfDNA) methylation are emerging as promising biomarkers for early diagnosis. Post-surgical circulating tumour DNA (ctDNA) can aid in evaluating minimal residual disease and personalising adjuvant treatment. In rectal cancer, ctDNA could improve response assessment to neoadjuvant therapy and risk stratification, especially in the era of organ-preservation trials. In the advanced setting, ctDNA analysis offers the opportunity to monitor treatment response and identify driver and resistance mutations more comprehensively than traditional tissue analysis, providing prognostic and predictive information. The aim of this review is to provide a detailed overview of the clinical applications and future perspectives of liquid biopsy in CRC.

PITPNC1 Suppress CD8+ T cell immune function and promote radioresistance in rectal cancer by modulating FASN/CD155

BACKGROUND

Radioresistance is a primary factor contributing to the failure of rectal cancer treatment. Immune suppression plays a significant role in the development of radioresistance. We have investigated the potential role of phosphatidylinositol transfer protein cytoplasmic 1 (PITPNC1) in regulating immune suppression associated with radioresistance.

METHODS

To elucidate the mechanisms by which PITPNC1 influences radioresistance, we established HT29, SW480, and MC38 radioresistant cell lines. The relationship between radioresistance and changes in the proportion of immune cells was verified through subcutaneous tumor models and flow cytometry. Changes in the expression levels of PITPNC1, FASN, and CD155 were determined using immunohistochemistry and western blotting techniques. The interplay between these proteins was investigated using immunofluorescence co-localization and immunoprecipitation assays. Additionally, siRNA and lentivirus-mediated gene knockdown or overexpression, as well as co-culture of tumor cells with PBMCs or CD8+ T cells and establishment of stable transgenic cell lines in vivo, were employed to validate the impact of the PITPNC1/FASN/CD155 pathway on CD8+ T cell immune function.

RESULTS

Under irradiation, the apoptosis rate and expression of apoptosis-related proteins in radioresistant colorectal cancer cell lines were significantly decreased, while the cell proliferation rate increased. In radioresistant tumor-bearing mice, the proportion of CD8+ T cells and IFN-γ production within immune cells decreased. Immunohistochemical analysis of human and animal tissue specimens resistant to radiotherapy showed a significant increase in the expression levels of PITPNC1, FASN, and CD155. Gene knockdown and rescue experiments demonstrated that PITPNC1 can regulate the expression of CD155 on the surface of tumor cells through FASN. In addition, co-culture experiments and in vivo tumor-bearing experiments have shown that silencing PITPNC1 can inhibit FASN/CD155, enhance CD8+ T cell immune function, promote colorectal cancer cell death, and ultimately reduce radioresistance in tumor-bearing models.

CONCLUSIONS

PITPNC1 regulates the expression of CD155 through FASN, inhibits CD8+ T cell immune function, and promotes radioresistance in rectal cancer.

Advances in MRI-Based Assessment of Rectal Cancer Post-Neoadjuvant Therapy: A Comprehensive Review

Rectal cancer presents significant diagnostic and therapeutic challenges, with neoadjuvant therapy playing a pivotal role in improving resectability and patient outcomes. MRI serves as a critical tool in assessing treatment response. However, differentiating viable tumor tissue from therapy-induced changes on MRI remains a complex task. In this comprehensive review, we explore treatment options for rectal cancer based on resectability status, focusing on the role of MRI in guiding therapeutic decisions. We delve into the nuances of MRI-based evaluation of treatment response following neoadjuvant therapy, paying particular attention to emerging techniques like radiomics. Drawing from our insights based on the literature, we provide essential recommendations for post-neoadjuvant therapy management of rectal cancer, all within the context of MRI-based findings.

Transanal local excision versus intersphincteric resection for low rectal cancer with stage ypT0-1ycN0 after neoadjuvant chemoradiotherapy: an inverse probability weighting analysis for oncological and functional outcomes

OBJECTIVES

This study aimed to compare the efficacy of local excision (LE) and intersphincteric resection (ISR) in patients with locally advanced rectal cancer who achieved a significant or complete pathological response following neoadjuvant chemoradiotherapy.

METHODS

We performed a retrospective analysis of data from patients with stage ypT0-1ycN0 low rectal cancer after neoadjuvant chemoradiotherapy who underwent LE or ISR between June 2016 and June 2021. Baseline characteristics, short-term outcomes, long-term oncological outcomes, and functional outcomes, were compared between the two groups. To reduce the selection bias, inverse probability of treatment weighting (IPTW) was performed.

RESULTS

This study included 106 patients (LE group: n = 51, ISR group: n = 55). There were significant differences in baseline characteristics between the two groups (P < 0.05). After IPTW, there were almost no significant differences in baseline data between the two groups. The LE group showed less postoperative complications and better function outcomes compared to the ISR group. The LE group had significantly lower rates of complications (13.7% vs. 36.4%, P = 0.014). There were no significant differences between the two groups in terms of long-term oncological outcomes.

CONCLUSIONS

For patients with locally advanced low rectal cancer achieving significant or complete pathological response after neoadjuvant therapy, both LE and ISR present comparable oncological outcomes. Yet, LE seems to show more advantages in terms of postoperative complications and functional outcomes. These findings offer important insights for surgical decision-making, emphasizing the necessity to consider both oncological and functional outcomes in selecting the optimal surgical approach.

Non-operative management involving chemoradiation therapy combined with high-dose-rate brachytherapy for T3 rectal cancer using a vaginal shielded cylindrical applicator: a technical report

It has been shown that a group of rectal cancer patients will achieve a pathological complete response following preoperative chemoradiotherapy, and non-operative management has recently gained attention. To escalate the tumour dose and increase the likelihood of pathological complete response, brachytherapy can play an important role in safely increasing the total dose. However, at the time this report was published, an applicator dedicated to rectal brachytherapy was unaffordable in Japan. Here, we report two T3 rectal cancer patients who were inoperable or refused surgery and treated by chemoradiotherapy following intracavitary brachytherapy involving a vaginal cylinder applicator with lead shielding.

Sense and non-sense of imaging in the era of organ preservation for rectal cancer

This review summarizes the current applications and benefits of imaging modalities for organ preservation in the treatment of rectal cancer. The concept of organ preservation in the treatment of rectal cancer has revolutionized the way rectal cancer is managed. Initially, organ preservation was limited to patients with locally advanced rectal cancer who needed neoadjuvant therapy to reduce tumor size before surgery and achieved complete response. However, neoadjuvant therapy is now increasingly utilized for smaller and less aggressive tumors to achieve primary organ preservation. Additionally, more intensive neoadjuvant strategies are employed to improve complete response rates and increase the chances of successful organ preservation. The selection of patients for organ preservation is a critical component of treatment, and imaging techniques such as digital rectal exam, endoscopy, and MRI are commonly used for this purpose. In this review, we provide an overview of what imaging modalities should be chosen and how they can aid in the selection and follow-up of patients undergoing organ-preserving strategies.

Long-term outcomes in a retrospective cohort of patients with rectal cancer with complete response after total neoadjuvant therapy: a propensity-score weighted analysis

Background

The watch-and-wait (W&W) strategy is a novel treatment option for patients with rectal cancer who have a strong desire for organ preservation. The study aimed to explore the long-term outcomes of the W&W strategy in a large cohort of rectal cancer patients who achieved a clinical complete response (cCR) after consolidation total neoadjuvant therapy (TNT), and to compare with patients who achieved a pathological complete response (pCR) after radical surgery.

Methods

The W&W group comprised patients who were assessed as having a cCR after consolidation TNT and adopted the W&W strategy. Patients who underwent standard resection and achieved a pCR were compared as a reference. Inverse probability of treatment weighting (IPTW)-adjusted Kaplan-Meier analysis with log-rank test was used to compare survival outcomes.

Results

We included 89 and 171 patients in the W&W and pCR groups, respectively. The median follow-up period was 45 and 58 months for the W&W and pCR groups, respectively. After IPTW adjustment, the 2-year local regrowth/recurrence rate for the W&W and pCR groups were 9.9% and 2.0%, respectively (p < 0.001). The W&W and pCR groups had similar 5-year outcomes, including overall survival, disease-free survival, and distant metastasis-free survival (all p > 0.05). No significant difference was observed in the rates of distant metastasis between patients in the W&W group with local regrowth and those without local regrowth (25% versus 6.2%, p = 0.119).

Conclusion

Patients who were managed with a W&W strategy after consolidation TNT had favorable survival outcomes, which were similar to those of patients with a pCR. The rate of local regrowth in W&W patients was lower in our study than in other studies as a result of the implementation of consolidation TNT.

Eastern Canadian Gastrointestinal Cancer Consensus Conference 2023

The annual Eastern Canadian Gastrointestinal Cancer Consensus Conference 2023 was held in Quebec City, Quebec 2-4 February 2023. The purpose of the conference was to develop consensus statements on emerging and evolving treatment paradigms. Participants included Canadian medical oncologists, radiation oncologists, pathologists and surgical oncologists from across Ontario, Quebec, and the Atlantic provinces. Consensus statements were developed following rapid review presentations and discussion of available literature. The recommendations proposed here represent the consensus opinions of physicians involved in the care of patients with gastrointestinal malignancies who participated in this meeting.

Rectal cancer lexicon 2023 revised and updated consensus statement from the Society of Abdominal Radiology Colorectal and Anal Cancer Disease-Focused Panel

The Society of Abdominal Radiology's Colorectal and Anal Cancer Disease-Focused Panel (DFP) first published a rectal cancer lexicon paper in 2019. Since that time, the DFP has published revised initial staging and restaging reporting templates, and a new SAR user guide to accompany the rectal MRI synoptic report (primary staging). This lexicon update summarizes interval developments, while conforming to the original lexicon 2019 format. Emphasis is placed on primary staging, treatment response, anatomic terminology, nodal staging, and the utility of specific sequences in the MRI protocol. A discussion of primary tumor staging reviews updates on tumor morphology and its clinical significance, T1 and T3 subclassifications and their clinical implications, T4a and T4b imaging findings/definitions, terminology updates on the use of MRF over CRM, and the conundrum of the external sphincter. A parallel section on treatment response reviews the clinical significance of near-complete response and introduces the lexicon of "regrowth" versus "recurrence". A review of relevant anatomy incorporates updated definitions and expert consensus of anatomic landmarks, including the NCCN's new definition of rectal upper margin and sigmoid take-off. A detailed review of nodal staging is also included, with attention to tumor location relative to the dentate line and locoregional lymph node designation, a new suggested size threshold for lateral lymph nodes and their indications for use, and imaging criteria used to differentiate tumor deposits from lymph nodes. Finally, new treatment terminologies such as organ preservation, TNT, TAMIS and watch-and-wait management are introduced. This 2023 version aims to serve as a concise set of up-to-date recommendations for radiologists, and discusses terminology, classification systems, MRI and clinical staging, and the evolving concepts in diagnosis and treatment of rectal cancer.

A primer on rectal MRI in patients on watch-and-wait treatment for rectal cancer

Total neoadjuvant treatment (TNT) for rectal cancer is becoming an accepted treatment paradigm and is changing the landscape of this disease, wherein up to 50% of patients who undergo TNT are able to avoid surgery. This places new demands on the radiologist in terms of interpreting degrees of response to treatment. This primer summarizes the Watch-and-Wait approach and the role of imaging, with illustrative "atlas-like" examples as an educational guide for radiologists. We present a brief literature summary of the evolution of rectal cancer treatment, with a focus on magnetic resonance imaging (MRI) assessment of response. We also discuss recommended guidelines and standards. We outline the common TNT approach entering mainstream practice. A heuristic and algorithmic approach to MRI interpretation is also offered. To illustrate management and common scenarios, we arranged the illustrative figures as follows: (I) Clinical complete response (cCR) achieved at the immediate post-TNT "decision point" scan time; (II) cCR achieved at some point during surveillance, later than the first post-TNT MRI; (III) near clinical complete response (nCR); (IV) incomplete clinical response (iCR); (V) discordant findings between MRI and endoscopy where MRI is falsely positive, even at follow-up; (VI) discordant cases where MRI seems to be falsely positive but is proven truly positive on follow-up endoscopy; (VII) cases where MRI is falsely negative; (VIII) regrowth of tumor in the primary tumor bed; (IX) regrowth outside the primary tumor bed; and (X) challenging scenarios, i.e., mucinous cases. This primer is offered to achieve its intended goal of educating radiologists on how to interpret MRI in patients with rectal cancer undergoing treatment using a TNT-type treatment paradigm and a Watch-and-Wait approach.

Validated Pretreatment Prediction Models for Response to Neoadjuvant Therapy in Patients with Rectal Cancer: A Systematic Review and Critical Appraisal

Pretreatment response prediction is crucial to select those patients with rectal cancer who will benefit from organ preservation strategies following (intensified) neoadjuvant therapy and to avoid unnecessary toxicity in those who will not. The combination of individual predictors in multivariable prediction models might improve predictive accuracy. The aim of this systematic review was to summarize and critically appraise validated pretreatment prediction models (other than radiomics-based models or image-based deep learning models) for response to neoadjuvant therapy in patients with rectal cancer and provide evidence-based recommendations for future research. MEDLINE via Ovid, Embase.com, and Scopus were searched for eligible studies published up to November 2022. A total of 5006 studies were screened and 16 were included for data extraction and risk of bias assessment using Prediction model Risk Of Bias Assessment Tool (PROBAST). All selected models were unique and grouped into five predictor categories: clinical, combined, genetics, metabolites, and pathology. Studies generally included patients with intermediate or advanced tumor stages who were treated with neoadjuvant chemoradiotherapy. Evaluated outcomes were pathological complete response and pathological tumor response. All studies were considered to have a high risk of bias and none of the models were externally validated in an independent study. Discriminative performances, estimated with the area under the curve (AUC), ranged per predictor category from 0.60 to 0.70 (clinical), 0.78 to 0.81 (combined), 0.66 to 0.91 (genetics), 0.54 to 0.80 (metabolites), and 0.71 to 0.91 (pathology). Model calibration outcomes were reported in five studies. Two collagen feature-based models showed the best predictive performance (AUCs 0.83-0.91 and good calibration). In conclusion, some pretreatment models for response prediction in rectal cancer show encouraging predictive potential but, given the high risk of bias in these studies, their value should be evaluated in future, well-designed studies.

Organ preservation strategies after neoadjuvant chemoimmunotherapy in resectable non-small cell lung cancer: a multicenter retrospective cohort study

BACKGROUND

Neoadjuvant chemoimmunotherapy has shown a good therapeutic effect on non-small cell lung cancer (NSCLC), which also opens up the possibility of applying organ preservation strategies. This study investigated the feasibility of modified surgery after potent neoadjuvant chemoimmunotherapy in central type NSCLC.

METHODS

In this multicenter retrospective cohort study, patients with central type NSCLC who received 2-4 cycles of neoadjuvant chemoimmunotherapy between January 2019 and June 2022 at Air Force Medical University Tangdu Hospital and Peking University People's Hospital were eligible. Patients were divided into modified and nonmodified groups according to the extent of surgery, after which, the safety and long-term prognosis of surgery were investigated.

RESULTS

A total of 84 patients were enrolled. Of 36 (42.9%) patients who underwent modified surgery, 21 patients underwent lobectomy, 12 patients underwent lobectomy with bronchoplasty, 2 patients underwent sleeve lobectomy, and 1 patient underwent bilobectomy. The modification rate for the initially estimated pneumonectomy, sleeve lobectomy, and bilobectomy was 48.6, 44.8, and 30%, respectively. Grades II-V postoperative complications were found in 5 (13.9%) patients in the modified group and 17 (35.4%) patients in the nonmodified group (relative risk, 0.393; 95% CI, 0.016-0.963; P =0.026). No significant difference was observed regarding the surgical approach, operative duration, blood loss, or R0 resection rate. The 2-year local recurrence rate was 3.7% (95% CI, 0.004-0.175) and 5.2% (95% CI, 0.012-0.168) in the modified group and nonmodified group, respectively. The 1-year PFS rate of modified and nonmodified groups was 97.1% (95% CI, 83.7-99.8) and 86.9% (95% CI, 73.4-94.4), respectively, while 2-year PFS were 89.8% (95% CI, 74.1-96.9) and 71.8% (95% CI, 56.7-83.4), respectively.

CONCLUSION

Applying organ preservation strategies, that is, undergoing modified surgery after neoadjuvant chemoimmunotherapy, is feasible for selected central type NSCLC patients with favorable safety and long-term survival.

Total Neoadjuvant Treatment for Locally Advanced Rectal Cancer Patients: Where Do We Stand?

The therapeutic landscape in locally advanced rectal cancer (LARC) has undergone a significant paradigm shift in recent years with the rising adoption of total neoadjuvant treatment (TNT). This comprehensive approach entails administering chemotherapy and radiation therapy before surgery, followed by optional adjuvant chemotherapy. To establish and deliver the optimal tailored treatment regimen to the patient, it is crucial to foster collaboration among a multidisciplinary team comprising healthcare professionals from various specialties, including medical oncology, radiation oncology, surgical oncology, radiology, and pathology. This review aims to provide insights into the current state of TNT for LARC and new emerging strategies to identify potential directions for future research and clinical practice, such as circulating tumor-DNA, immunotherapy in mismatch-repair-deficient tumors, and nonoperative management.

Short-course radiotherapy for rectal cancer: real-world evidence in Argentina

Background

Short-course radiotherapy (SCRT) of 25 Gy in five daily fractions is a recommended strategy in the neoadjuvant setting for resectable locally advanced rectal cancer (LARC), as well as in cases of metastatic disease for local control. There is scarce information regarding the use of SCRT for patients who have received nonoperative management.

Objectives

To describe the characteristics of patients who received treatment with SCRT for LARC and metastatic rectal cancer, toxicity, and the approach after radiation treatment.

Methods

This is a retrospective analysis of all patients who underwent SCRT for rectal cancer at the Alexander Fleming Institute from March 2014 to June 2022.

Results

In total, 44 patients were treated with SCRT. The majority were male (29, 66%), with a median age of 59 years (interquartile range 46-73). Most patients had stage IV disease (26, 59.1%), followed by LARC (18, 40.9%). Most lesions were located in the middle rectum (30, 68%). The majority of LARC patients underwent SCRT followed by consolidation chemotherapy (ChT) (16/18, 89%), while most patients with metastatic disease underwent SCRT followed by consolidation ChT (14/26, 53.8%). A clinical complete response (cCR) was documented in 8/44, 18.2% of patients. Most patients with LARC and cCR were managed by a watch and wait approach (5/18, 27.7%). Local recurrence was observed in LARC cases (2/18, 11.1%). Patients who underwent SCRT following consolidation ChT were more likely to have adverse events (AEs) than those undergoing induction ChT following SCRT (11/30, 36.7% versus 3/12, 25%, p = 0.02).

Conclusion

In a subgroup of patients diagnosed with LARC and treated with SCRT followed by ChT, surgical treatment could be omitted after they achieved a cCR. Local recurrence was similar to that reported in a previous study. SCRT is a reasonable option for local disease control in stage IV disease, yielding low toxicity rates. Therefore, decisions must be made by a multidisciplinary team. Prospective studies are necessary to reach further conclusions.

MRI-based radiomic score increased mrTRG accuracy in predicting rectal cancer response to neoadjuvant therapy

PURPOSE

To develop a magnetic resonance imaging (MRI)-based radiomics score, i.e., "rad-score," and to investigate the performance of rad-score alone and combined with mrTRG in predicting pathologic complete response (pCR) in patients with locally advanced rectal cancer following neoadjuvant chemoradiation therapy.

METHODS

This retrospective study included consecutive patients with LARC who underwent neoadjuvant chemoradiotherapy followed by surgery from between July 2011 to November 2015. Volumes of interest of the entire tumor on baseline rectal MRI and of the tumor bed on restaging rectal MRI were manually segmented on T2-weighted images. The radiologist also provided the ymrTRG score on the restaging MRI. Radiomic score (rad-score) was calculated and optimal cut-off points for both mrTRG and rad-score to predict pCR were selected using Youden's J statistic.

RESULTS

Of 180 patients (mean age = 63 years; 60% men), 33/180 (18%) achieved pCR. High rad-score (> - 1.49) yielded an area under the curve (AUC) of 0.758, comparable to ymrTRG 1-2 which yielded an AUC of 0.759. The combination of high rad-score and ymrTRG 1-2 yielded a significantly higher AUC of 0.836 compared with ymrTRG 1-2 and high rad-score alone (p < 0.001). A logistic regression model incorporating both high rad-score and mrTRG 1-2 was built to calculate adjusted odds ratios for pCR, which was 4.85 (p < 0.001).

CONCLUSION

Our study demonstrates that a rectal restaging MRI-based rad-score had comparable diagnostic performance to ymrTRG. Moreover, the combined rad-score and ymrTRG model yielded a significant better diagnostic performance for predicting pCR.

New Opportunities for Minimizing Toxicity in Rectal Cancer Management

Advances in multimodal management of locally advanced rectal cancer (LARC), consisting of preoperative chemotherapy and/or radiotherapy followed by surgery with or without adjuvant chemotherapy, have improved local disease control and patient survival but are associated with significant risk for acute and long-term morbidity. Recently published trials, evaluating treatment dose intensification via the addition of preoperative induction or consolidation chemotherapy (total neoadjuvant therapy [TNT]), have demonstrated improved tumor response rates while maintaining acceptable toxicity. In addition, TNT has led to an increased number of patients achieving a clinical complete response and thus eligible to pursue a nonoperative, organ-preserving, watch and wait approach, thereby avoiding toxicities associated with surgery, such as bowel dysfunction and stoma-related complications. Ongoing trials using immune checkpoint inhibitors in patients with mismatch repair-deficient tumors suggest that this subgroup of patients with LARC could potentially be treated with immunotherapy alone, sparing them the toxicity associated with preoperative treatment and surgery. However, the majority of rectal cancers are mismatch repair-proficient and less responsive to immune checkpoint inhibitors and require multimodal management. The synergy noted in preclinical studies between immunotherapy and radiotherapy on immunogenic tumor cell death has led to the design of ongoing clinical trials that explore the benefit of combining radiotherapy, chemotherapy, and immunotherapy (mainly of immune checkpoint inhibitors) and aim to increase the number of patients eligible for organ preservation.

Watch and wait after neoadjuvant treatment in rectal cancer: comparison of outcomes in patients with and without a complete response at first reassessment in the International Watch & Wait Database (IWWD)

BACKGROUND

In rectal cancer, watch and wait for patients with a cCR after neoadjuvant treatment has an established evidence base. However, there is a lack of consensus on the definition and management of a near-cCR. This study aimed to compare outcomes in patients who achieved a cCR at first reassessment versus later reassessment.

METHODS

This registry study included patients from the International Watch & Wait Database. Patients were categorized as having a cCR at first reassessment or at later reassessment (that is near-cCR at first reassessment) based on MRI and endoscopy. Organ preservation, distant metastasis-free survival, and overall survival rates were calculated. Subgroup analyses were done for near-cCR groups based on the response evaluation according to modality.

RESULTS

A total of 1010 patients were identified. At first reassessment, 608 patients had a cCR; 402 had a cCR at later reassessment. Median follow-up was 2.6 years for patients with a cCR at first reassessment and 2.9 years for those with a cCR at later reassessment. The 2-year organ preservation rate was 77.8 (95 per cent c.i. 74.2 to 81.5) and 79.3 (75.1 to 83.7) per cent respectively (P = 0.499). Similarly, no differences were found between groups in distant metastasis-free survival or overall survival rate. Subgroup analyses showed a higher organ preservation rate in the group with a near-cCR categorized exclusively by MRI.

CONCLUSION

Oncological outcomes for patients with a cCR at later reassessment are no worse than those of patients with a cCR at first reassessment.

Restaging rectal cancer following neoadjuvant chemoradiotherapy

Correct tumour restaging is pivotal for identifying the most personalised surgical treatment for patients with locally advanced rectal cancer undergoing neoadjuvant therapy, and works to avoid both poor oncological outcome and overtreatment. Digital rectal examination, endoscopy, and pelvic magnetic resonance imaging are the recommended modalities for local tumour restaging, while chest and abdominal computed tomography are utilised for the assessment of distant disease. The optimal length of time between neoadjuvant treatment and restaging, in terms of both oncological safety and clinical effectiveness of treatment, remains unclear, especially for patients receiving prolonged total neoadjuvant therapy. The timely identification of patients who are radioresistant and at risk of disease progression remains challenging.

[Rectal cancer update: postneoadjuvant staging]

Over the last two decades, magnetic resonance imaging (MRI) has continuously been gaining influence in modern management of rectal cancer. Bringing morphological and functional features together improves the differentiation of responders from nonresponders, provides for accurate surgical planning, intensified radiation therapy regimes, and watch-and-wait strategies. A shift from TNM staging towards risk stratification of rectal cancer patients, patient selection to increasingly individualized therapies, and intensified surveillance has contributed to the transformation of rectal MRI into a true gamechanger.

[Interpretation of Rectal MRI after Neoadjuvant Treatment in Patients with Rectal Cancer]

MRI is currently the imaging modality of choice to evaluate rectal cancer after neoadjuvant treatment. The purposes of restaging MRI are to assess the resectability of rectal cancer and to decide whether organ preservation strategies can be applied in patients with a complete clinical response. This review article indicates the key MRI features needed to evaluate rectal cancer after neoadjuvant treatment using a systematic approach. Assessment of primary tumor response including MRI findings to predict a complete response is discussed. Additionally, MRI evaluation of the relationship between the primary tumor and adjacent structures, lymph node response, extramural venous invasion, and tumor deposits after neoadjuvant treatment is presented. Knowledge of these imaging features and their clinical relevance may help radiologists provide an accurate and clinically valuable interpretation of restaging rectal MRI.

Polyphotosensitizer-Based Nanoparticles with Michael Addition Acceptors Inhibiting GST Activity and Cisplatin Deactivation for Enhanced Chemotherapy and Photodynamic Immunotherapy

Glutathione S-transferase (GST), which is a key enzyme in the conjugation reaction of glutathione (GSH), is overexpressed in cancer cells, leading to cisplatin deactivation and ultimately drug resistance. In addition, many tumors are immune "cold tumors," limiting the application of immune checkpoint inhibitors. Herein, a reactive oxygen species (ROS)-responsive polyphotosensitizer-based nanoparticle (NP2) with Michael addition acceptors inhibiting GST activity and cisplatin deactivation is designed. Under the 808 nm light irradiation, on the one hand, the Michael addition acceptor in NP2 can react with GST and inhibit its activity, thereby decreasing the GSH conjugation and reducing the GSH-mediated deactivation of cisplatin and improving its chemotherapeutic effect. On the other hand, NP2+L induces more ROS production in prostate tumor cells, which can further induce type II immunogenic cell death (ICD) and stimulate a stronger antitumor immune response. It is found that NP2 under the 808 nm light irradiation (NP2+L) can increase PD-L1 expression on the surface of prostate cancer cells. Subsequently, NP2+L combined with PD-L1 treatment is found to simultaneously enhance the efficacies of chemotherapy and photodynamic immunotherapy in prostate tumors, providing a new paradigm for the clinical multimodal treatment of tumors.

Total neoadjuvant treatment and organ preservation strategies in the management of localized rectal cancer: a narrative review and evidence-based algorithm

The multimodal approach with total mesorectal excision preceded by neoadjuvant (chemo)radiotherapy represented the mainstay treatment for locally advanced rectal cancer (LARC) for a long time. However, the benefit of adjuvant chemotherapy in terms of distant relapse reduction is limited. Recently, chemotherapy regimens administered before surgery and incorporated with (chemo)radiotherapy in total neoadjuvant treatment protocols have been established as new options in the management of LARC. Meanwhile, patients with clinical complete response to neoadjuvant treatment can benefit from organ preservation strategies, aimed at sparing surgery and long-term post-operative morbidities, while preserving an adequate disease control. However, the introduction of a non-operative management in clinical practice is a matter of debate with some concerns regarding the risk of local recurrence and long-term outcomes. In this review, we discuss how these recent advances are reshaping the multimodal management of localized rectal cancer and propose an algorithm to place them in the clinical practice.

Advances in Radiotherapy for Rectal Cancer

The current preferred standard of care management for patients with locally advanced rectal cancer is total neoadjuvant therapy, in which all chemotherapy and radiotherapy is delivered before surgery. Within this approach, developed in response to persistently high distant failure rates despite excellent local control with preoperative chemoradiotherapy, there remains questions regarding the optimal radiotherapy regimen (short course vs long course) and sequencing of chemotherapy (induction vs consolidation).

Watch-and-Wait Approach to Rectal Cancer: The Role of Imaging

The diagnosis and treatment of rectal cancer have evolved dramatically over the past several decades. At the same time, its incidence has increased in younger populations. This review will inform the reader of advances in both diagnosis and treatment. These advances have led to the watch-and-wait approach, otherwise known as nonsurgical management. This review briefly outlines changes in medical and surgical treatment, advances in MRI technology and interpretation, and landmark studies or trials that have led to this exciting juncture. Herein, the authors delve into current state-of-the-art methods to assess response to treatment with MRI and endoscopy. Currently, these methods for avoiding surgery can be used to detect a complete clinical response in as many as 50% of patients with rectal cancer. Finally, the limitations of imaging and endoscopy and future challenges will be discussed.