Organ Preservation in cT2N0 Rectal Cancer After Neoadjuvant Chemoradiation Therapy: The Impact of Radiation Therapy Dose-escalation and Consolidation Chemotherapy

OBJECTIVE

To demonstrate the difference in organ-preservation rates and avoidance of definitive surgery among cT2N0 rectal cancer patients undergoing 2 different chemoradiation (CRT) regimens.

BACKGROUND

Patients with cT2N0 rectal cancer are more likely to develop complete response to neoadjuvant CRT. Organ preservation has been considered an alternative treatment strategy for selected patients. Radiation dose-escalation and consolidation chemotherapy have been associated with increased rates of response and may improve chances of organ preservation among these patients.

METHODS

Patients with distal and nonmetastatic cT2N0 rectal cancer managed by neoadjuvant CRT were retrospectively reviewed. Patients undergoing standard CRT (50.4 Gy and 2 cycles of 5-FU-based chemotherapy) were compared with those undergoing extended CRT (54 Gy and 6 cycles of 5-FU-based chemotherapy). Patients were assessed for tumor response at 8 to 10 weeks. Patients with complete clinical response (cCR) underwent organ-preservation strategy ("Watch and Wait"). Patients were referred to salvage surgery in the event of local recurrence during follow-up.

RESULTS

Thirty-five patients underwent standard and 46 patients extended CRT. Patients undergoing extended CRT were more likely to undergo organ preservation and avoid definitive surgical resection at 5years (67% vs 30%; P = 0.001). After development of a cCR, surgery-free survival is similar between extended and standard CRT groups at 5 years (78% vs 56%; P = 0.12).

CONCLUSIONS

Dose-escalation and consolidation chemotherapy leads to increased long-term organ-preservation rates among cT2N0 rectal cancer. After achievement of a cCR, the risk for local recurrence and need for salvage surgery is similar, irrespective of the CRT regimen.

New Strategies in Rectal Cancer

In recent years, our understanding of rectal cancer has improved, including how locally advanced disease responds to chemotherapy and radiation. This has led to new innovations and advances in the treatment of rectal cancer, which includes organ-preserving strategies for responsive disease, and minimally invasive approaces for the performance of total mesorectal excision/protectomyh for persistently advanced disease. This article discusses new strategies for rectal cancer therapy, including Watch and Wait, local excision, minimally invasive proctectomy, and transanal total mesorectal excision particularly in the setting of preoperative multimodality treatment.

Is neoadjuvant chemoradiation with dose-escalation and consolidation chemotherapy sufficient to increase surgery-free and distant metastases-free survival in baseline cT3 rectal cancer?

Patients with cT3 rectal cancer are less likely to develop complete response to neoadjuvant chemoradiation (nCRT) and still face significant risk for systemic relapse. In this setting, radiation (RT) dose-escalation and consolidation chemotherapy in "extended" nCRT regimens have been suggested to improve primary tumor response and decrease the risks of systemic recurrences. For these reasons we compared surgery-free and distant-metastases free survival among cT3 patients undergoing standard or extended nCRT.

METHODS

Patients with distal and non-metastatic T3 rectal cancer managed by nCRT were retrospectively reviewed. Patients undergoing standard CRT (50.4 Gy and 2 cycles of 5FU-based chemotherapy) were compared to those undergoing extended CRT (54 Gy and 6 cycles of 5FU-based chemotherapy). Patients were assessed for tumor response at 8-10 weeks. Patients with complete clinical response (cCR) underwent organ-preservation strategy (Watch & Wait). Patients were referred to salvage surgery in the event of local recurrence during follow-up. Cox's logistic regression was performed to identify independent features associated with improved surgery-free survival after cCR and distant-metastases-free survival.

RESULTS

155 patients underwent standard and 66 patients extended CRT. Patients undergoing extended CRT were more likely to harbor larger initial tumor size (p = 0.04), baseline nodal metastases (cN+; p < 0.001) and higher tumor location (p = 0.02). Cox-regression analysis revealed that the type of nCRT regimen was not independently associated with distinct surgery-free survival after cCR or distant-metastases-free survival (p > 0.05).

CONCLUSIONS

Dose-escalation and consolidation chemotherapy are insufficient to increase long-term surgery-free survival among cT3 rectal cancer patients and provides no advantage in distant metastases-free survival.

Effect of Akt activation and experimental pharmacological inhibition on responses to neoadjuvant chemoradiotherapy in rectal cancer

BACKGROUND

Neoadjuvant chemoradiotherapy (CRT) is one of the preferred initial treatment strategies for locally advanced rectal cancer. Responses are variable, and most patients still require surgery. The aim of this study was to identify molecular mechanisms determining poor response to CRT.

METHODS

Global gene expression and pathway enrichment were assessed in pretreatment biopsies from patients with non-metastatic cT2-4 N0-2 rectal cancer within 7 cm of the anal verge. Downstream Akt activation was assessed in an independent set of pretreatment biopsies and in colorectal cancer cell lines using immunohistochemistry and western blot respectively. The radiosensitizing effects of the Akt inhibitor MK2206 were assessed using clonogenic assays and xenografts in immunodeficient mice.

RESULTS

A total of 350 differentially expressed genes were identified, of which 123 were upregulated and 199 downregulated in tumours from poor responders. Mitochondrial oxidative phosphorylation (P < 0·001) and phosphatidylinositol signalling pathways (P < 0·050) were identified as significantly enriched pathways among the set of differentially expressed genes. Deregulation of both pathways is known to result in Akt activation, and high immunoexpression of phosphorylated Akt S473 was observed among patients with a poor histological response (tumour regression grade 0-2) to CRT (75 per cent versus 48 per cent in those with a good or complete response; P = 0·016). Akt activation was also confirmed in the radioresistant cell line SW480, and a 50 per cent improvement in sensitivity to CRT was observed in vitro and in vivo when SW480 cells were exposed to the Akt inhibitor MK2206 in combination with radiation and 5-fluorouracil.

CONCLUSION

Akt activation is a key event in the response to CRT. Pharmacological inhibition of Akt activation may enhance the effects of CRT. Surgical relevance Organ preservation is an attractive alternative in rectal cancer management following neoadjuvant chemoradiotherapy (CRT) to avoid the morbidity of radical surgery. Molecular steps associated with tumour response to CRT may provide a useful tool for the identification of patients who are candidates for no immediate surgery. In this study, tumours resistant to CRT were more likely to have activation of specific genetic pathways that result in phosphorylated Akt (pAkt) activation. Pretreatment biopsy tissues with high immunoexpression of pAkt were more likely to exhibit a poor histological response to CRT. In addition, the introduction of a pAkt inhibitor to cancer cell lines in vitro and in vivo led to a significant improvement in sensitivity to CRT. Identification of pAkt-activated tumours may thus allow the identification of poor responders to CRT. In addition, the concomitant use of pAkt inhibitors to increase sensitivity to CRT in patients with rectal cancer may constitute an interesting strategy for increasing the chance of a complete response to treatment and organ preservation.

Management of the Complete Clinical Response

Organ preservation is considered in the management of selected patients with rectal cancer. Complete clinical response observed after neoadjuvant chemoradiation for rectal cancer is one of these cases. Patients who present complete clinical response are candidates to the watch-and-wait approach, when radical surgery is not immediately performed and is offered only to patients in the event of a local relapse. These patients are included in a strict follow-up, and up of 70% of them will never be operated during the follow-up. This strategy is associated with similar oncological outcomes as patients operated on, and the advantage of avoiding the morbidity associated to the radical operation. In this article we will discuss in detail the best candidates for this approach, the protocol itself, and the long-term outcomes.

Magnetic resonance imaging following neoadjuvant chemoradiation and transanal endoscopic microsurgery for rectal cancer

AIM

Full-thickness local excision after neoadjuvant chemoradiotherapy (CRT) for patients with rectal cancer and incomplete clinical response has been a treatment strategy for organ preservation. Follow-up of these patients is challenging since anatomic distortion and postoperative changes may be clinically indistinguishable from tumour recurrence. MRI may have a role in detecting recurrence. The aim of this study was to describe the MRI findings during follow-up in patients having local excision following CRT with and without local recurrence.

METHOD

The data were collected retrospectively from a single centre. Fifty-three patients with rectal cancer who had full-thickness local excision after neoadjuvant CRT and near-complete response were eligible for the study. Patients with local recurrence were treated by radical salvage surgery. The main outcome was local MRI assessment findings during follow-up.

RESULTS

Fifteen patients (five who developed local recurrence and 10 with no evidence of local recurrence) had MR images available for review and were included in the study. High signal intensity and thickening of the rectal wall were present in all patients with recurrent disease within the rectal wall. Overall, 80% of the patients with recurrence showed diffusion restriction. MRI mesorectal fascia status and circumferential resection margin showed agreement in all cases. A low signal intensity scar was seen in all patients without recurrent disease.

CONCLUSION

MRI shows high signal intensity and thickening of the rectal wall in recurrent disease in comparison to a low signal intensity fibrotic scar in non-recurrent disease. These findings may be useful in surveillance of these patients.

Local Excision and Endoscopic Resections for Early Rectal Cancer

Radical surgery is considered as the standard treatment for rectal cancer. Transanal local excision has been considered an interesting alternative for the management of selected patients with rectal cancers for many decades. Different approaches had been considered for local excision, from endoscopic submucosal dissection to resections using platforms, such as transanal endoscopic microsurgery or transanal minimally invasive surgery. Identifying the ideal candidate for this approach is crucial, as a local failure after local excision is associated with poor outcomes, even for an initial early rectal tumor. In this article, the diagnostic tools and criteria to select patients for local excision, the different modalities used, and the outcomes are discussed.

Laparoscopic colorectal surgery and discharge within 24 h-who is at risk for readmission?

AIM

The aim was to describe risk factors for hospital readmission in patients undergoing laparoscopic colorectal procedures and being discharged in ≤24 h.

METHOD

All consecutive patients undergoing minimally invasive colorectal surgery between 2010 and 2019 from a single institution were retrospectively reviewed. All patients were included in an enhanced recovery programme. Patients who met criteria for hospital discharge were compared according to the need for readmission in a 45-day follow-up.

RESULTS

In all, 664 patients underwent minimally invasive colorectal surgery during the study period and 237 (35.7%) were discharged in ≤24 h. Readmission was required in 16 (6.8%) patients discharged in ≤24 h and no postoperative mortality was observed in this group. Patients discharged in ≤24 h were more likely to have benign disease (P < 0.001), fewer associated procedures (P < 0.025) and intracorporeal anastomoses (P < 0.001). The type of surgical procedure (abdominoperineal resection), low rectal tumour, malignant disease, older age and longer operating time were associated with readmission. Age (OR 1.06; P = 0.037), malignant disease (OR 4.39; P = 0.05) and operating time (OR 1.03; P < 0.001) were identified as independent predictive factors for readmission amongst patients being discharged in ≤24 h.

CONCLUSION

Highly selected patients undergoing minimally invasive procedures in colorectal surgery may be safely discharged within 24 h following the procedure. High-risk features for readmission include older age, malignant disease and longer operating time.

Local tumor regrowth after clinical complete response following neoadjuvant therapy for rectal cancer: what happens when organ preservation falls short

Organ preservation strategies, especially watch and wait, after neoadjuvant treatment in locally advanced rectal cancer, have become topics that generate significant interest, for both patients and clinicians. The obvious advantage of these strategies is the avoidance of surgery with its associated risks and functional consequences. Over time, it has become evident that these strategies offer acceptable safety in oncological terms and, in most patients, allows preservation of the rectum without harming patients in terms of distant metastasis or survival. However, there is a small group of patients in whom the tumor returns after an initially diagnosed clinical complete response; patients with local tumor regrowth. The main threat in these patients is not simply local disease, which can be successfully managed in most cases, but the possible effects it may have on distant metastases. The pathophysiology of the phenomenon of local tumor regrowth is not well known and, therefore, strategies to minimize possible impact on survival are not well defined. Our aim is to review key issues in this subgroup that pose a substantial threat to the safety and viability of organ-preserving and watch-and-wait strategies. We also explore possible pathophysiologic explanations and future directions and perspectives that may improve both local and systemic disease control.

Transanal Local Excision of Rectal Cancer after Neoadjuvant Chemoradiation: Is There a Place for It or Should Be Avoided at All Costs?

Tumor response to neoadjuvant chemoradiation (nCRT) with tumor downsizing and downstaging has significantly impacted the number of patients considered to be appropriate candidates for transanal local excision (TLE). Some patients may harbor small residual lesions, restricted to the bowel wall. These patients, who exhibit major response ("near-complete") by digital rectal examination, endoscopic assessment, and radiological assessment may be considered for this approach. Although TLE is associated with minimal postoperative morbidity, a few clinical consequences and oncological outcomes must be evaluated in advance and with caution. In the setting of nCRT, a higher risk for clinically relevant wound dehiscences leading to a considerable risk for readmission for pain management has been observed. Worse anorectal function (still better than after total mesorectal excision [TME]), worsening in the quality of TME specimen, and higher rates of abdominal resections (in cases requiring completion TME) have been reported. The exuberant scar observed in the area of TLE also represents a challenging finding during follow-up of these patients. Local excision should be probably restricted for patients with primary tumors located at or below the level of the anorectal ring (magnetic resonance defined). These patients are otherwise candidates for abdominal perineal resections or ultra-low anterior resections with coloanal anastomosis frequently requiring definitive stomas or considerably poor anorectal function.

Nonoperative Management for T2 Low Rectal Cancer: A Western Approach

The possibility of organ preservation in early rectal cancer has gained popularity during recent years. Patients with early tumor stage and low risk for local recurrence do not usually require neoadjuvant chemoradiation for oncological reasons. However, these patients may be considered for chemoradiation exclusively for the purpose of achieving a complete clinical response and avoid total mesorectal excision. In addition, cT2 tumors may be more likely to develop complete response to neoadjuvant therapy and may constitute ideal candidates for organ-preserving strategies. In the setting where the use of chemoradiation is exclusively used to avoid major surgery, one should consider maximizing tumor response. In this article, we will focus on the rationale, indications, and outcomes of patients with early rectal cancer being treated by neoadjuvant chemoradiation to achieve organ preservation by avoiding total mesorectal excision.

Watch and Wait Approach for Rectal Cancer

The administration of neoadjuvant chemoradiotherapy (nCRT) followed by total mesorrectal excision (TME) and selective use of adjuvant chemotherapy can still be considered the standard of care in locally advanced rectal cancer (LARC). However, avoiding sequelae of TME and entering a narrow follow-up program of watch and wait (W&W), in select cases that achieve a comparable clinical complete response (cCR) to nCRT, is now very attractive to both patients and clinicians. Many advances based on well-designed studies and long-term data coming from big multicenter cohorts have drawn some important conclusions and warnings regarding this strategy. In order to safely implement W&W, it is important consider proper selection of cases, best treatment options, surveillance strategy and the attitudes towards near complete responses or even tumor regrowth. The present review offers a comprehensive overview of W&W strategy from its origins to the most current literature, from a practical point of view focused on daily clinical practice, without losing sight of the most important future prospects in this area.

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.

A multi-centre randomized controlled trial investigating Consolidation Chemotherapy with and without oxaliplatin in distal rectal cancer and Watch & Wait

BACKGROUND

Neoadjuvant chemoradiation(nCRT) has been considered the preferred initial treatment strategy for distal rectal cancer. Advantages of this approach include improved local control after radical surgery but also the opportunity for organ preserving strategies (Watch and Wait-WW). Consolidation chemotherapy(cCT) regimens using fluoropyrimidine-based with or without oxalipatin following nCRT have demonstrated to increase complete response and organ preservation rates among these patients. However, the benefit of adding oxaliplatin to cCT compared to fluoropirimidine alone regimens in terms of primary tumor response remains unclear. Since oxalipatin-treatment may be associated with considerable toxicity, it becomes imperative to understand the benefit of its incorporation into standard cCT regimens in terms of primary tumor response. The aim of the present trial is to compare the outcomes of 2 different cCT regimens following nCRT (fluoropyrimidine-alone versus fluoropyrimidine + oxaliplatin) for patients with distal rectal cancer.

METHODS

In this multi-centre study, patients with magnetic resonance-defined distal rectal tumors will be randomized on a 1:1 ratio to receive long-course chemoradiation (54 Gy) followed by cCT with fluoropyrimidine alone versus fluoropyrimidine + oxaliplatin. Magnetic resonance(MR) will be analyzed centrally prior to patient inclusion and randomization. mrT2-3N0-1 tumor located no more than 1 cm above the anorectal ring determined by sagittal views on MR will be eligible for the study. Tumor response will be assessed after 12 weeks from radiotherapy(RT) completion. Patients with clinical complete response (clinical, endoscopic and radiological) may be enrolled in an organ-preservation program(WW). The primary endpoint of this trial is decision to organ-preservation surveillance (WW) at 18 weeks from RT completion. Secondary endpoints are 3-year surgery-free survival, TME-free survival, distant metastases-free survival, local regrowth-free survival and colostomy-free survival.

DISCUSSION

Long-course nCRT with cCT is associated with improved complete response rates and may be a very attractive alternative to increase the chances for organ-preservation strategies. Fluoropyrimidine-based cCT with or without oxaliplatin has never been investigated in the setting of a randomized trial to compare clinical response rates and the possibility of organ-preservation. The outcomes of this study may significantly impact clinical practice of patients with distal rectal cancer interested in organ-preservation.

TRIAL REGISTRATION

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gov NCT05000697; registered on August 11^th, 2021.

Local Regrowth and the Risk of Distant Metastases Among Patients Undergoing Watch-and-Wait for Rectal Cancer: What Is the Best Control Group? Multicenter Retrospective Study

BACKGROUND

A proportion of rectal cancer patients who achieve a clinical complete response may develop local regrowth. Although salvage appears to provide appropriate local control, the risk of distant metastases is less known.

OBJECTIVE

To compare the risk of distant metastases between patients who achieve a clinical complete response (watch-and-wait strategy) and subsequent local regrowth and patients managed by surgery after chemoradiation.

DESIGN

Retrospective multicenter cohort study.

SETTINGS

This study used data of patients from 3 institutions who were treated between 1993 and 2019.

PATIENTS

Patients with initial clinical complete response (after neoadjuvant therapy) followed by local regrowth and patients with near-complete pathological response (≤10%) after straightforward surgery after chemoradiation were included.

MAIN OUTCOME MEASURES

Univariate and multivariate analyses were performed to identify risk factors for distant metastases. Kaplan-Meier curves were created (log-rank test) to compare survival outcomes. Analyses were performed using time zero as last day of radiation therapy or as date of salvage resection in the local regrowth group.

RESULTS

Twenty-one of 79 patients with local regrowth developed distant metastases, whereas only 10 of 74 after upfront total mesorectal excision following neoadjuvant chemoradiation therapy ( p  = 0.04). Local regrowth and final pathology (ypT3-4) were the only independent risk factors associated with distant metastases. When using date of salvage resection as time zero, distant metastases-free survival rates were significantly inferior for patients with local regrowth (70% vs 86%; p  = 0.01).

LIMITATIONS

Small number of patients, many neoadjuvant therapies, and selection bias.

CONCLUSIONS

Patients undergoing watch-and-wait strategy who develop local regrowth are at higher risk for development of distant metastases compared to patients with near-complete pathological response managed by upfront surgery after chemoradiation. See Video Abstract.

NUEVO CRECIMIENTO LOCAL Y EL RIESGO DE METSTASIS A DISTANCIA ENTRE PACIENTES SOMETIDOS A OBSERVACIN Y ESPERA POR CNCER DE RECTO CUL ES EL MEJOR GRUPO DE CONTROL ESTUDIO RETROSPECTIVO MUTICNTRICO

ANTECEDENTES:Una proporción de pacientes que logran una respuesta clínica completa pueden desarrollar un nuevo crecimiento local. Si bien el rescate parece proporcionar un control local apropiado, el riesgo de metástasis a distancia es menos conocido.OBJETIVO:Comparar el riesgo de metástasis a distancia entre los pacientes que logran una respuesta clínica completa (estrategia de observación y espera) y el nuevo crecimiento local posterior con los pacientes tratados con cirugía después de la quimiorradiación.DISEÑO:Estudio de cohorte multicéntrico retrospectivo.CONFIGURACIÓN:Este estudio utilizó datos de pacientes de 3 instituciones que fueron tratados entre 1993 y 2019.PACIENTES:Pacientes con respuesta clínica completa inicial (después de la terapia neoadyuvante) seguida de crecimiento local nuevo y pacientes con respuesta patológica casi completa (≤10 %) después de cirugía directa después de quimiorradiación.PRINCIPALES MEDIDAS DE RESULTADO:Se realizó un análisis univariante/multivariante para identificar los factores de riesgo de metástasis a distancia. Se crearon curvas de Kaplan-Meier (prueba de rango logarítmico) para comparar los resultados de supervivencia. El análisis se realizó utilizando el tiempo cero como último día de radioterapia (1) o como fecha de resección de rescate (2) en el grupo de recrecimiento local.RESULTADOS:Veintiuno de 79 pacientes con recrecimiento local desarrollaron metástasis a distancia, mientras que solo 10 de 74 después de una cirugía sencilla (p = 0,04). El recrecimiento local y la patología final (ypT3-4) fueron los únicos factores de riesgo independientes asociados con las metástasis a distancia. Cuando se utilizó la fecha de la resección de rescate como tiempo cero, las tasas de supervivencia sin metástasis a distancia fueron significativamente inferiores para los pacientes con recrecimiento local (70 frente a 86 %; p = 0,01).LIMITACIONES:Pequeño número de pacientes, muchas terapias neoadyuvantes, sesgo de selección.CONCLUSIONES:Los pacientes sometidos a observación y espera que desarrollan un nuevo crecimiento local tienen un mayor riesgo de desarrollar metástasis a distancia en comparación con los pacientes con una respuesta patológica casi completa manejados con cirugía por adelantado después de la quimiorradiación. (Traducción-Dr. Xavier Delgadillo ).

Risk of distant metastasis after local excision for near-complete response versus salvage surgery for local regrowth in rectal cancer: Results from an international registry

AIM

Watch and Wait (WW) strategy is currently used for mid/low rectal adenocarcinoma after neoadjuvant treatment (NAT). Local regrowth (LR) is a well-known risk, but its impact on distant metastasis (DM) is increasingly debated. This study aimed to assess the rate of DM after local excision (LE) for near-complete clinical response (ncCR) at restaging versus salvage surgery for regrowth following WW.

METHOD

Retrospective analysis of DM rates from a prospective international registry, comparing patients with ncCR after NAT who underwent LE and patients with initial complete clinical response (cCR) and WW strategy, who underwent salvage surgery for regrowth. The primary endpoint was the 5-year distant metastasis-free survival (5y-DMFS). Univariate/Multivariate analysis were performed to identify risk factors of DM.

RESULTS

Among 138 patients included, 59 had LE for ncCR and 79 had salvage surgery after regrowth including TME (n = 23), APR (n = 30) and LE (n = 26). The 5y-DMFS was lower in patients with surgery at regrowth, 71 % vs. 93 % (p = 0.006). LR was the only independent risk factor associated with DM (OR:3.89; 95 % CI:1.34-11.25; p = 0.012). When only patients managed by salvage LE for LR are considered, 5y-DMFS was equivalent to LE at restaging (87 vs. 93; p = 0.442).

CONCLUSION

Patients with rectal cancer undergoing LE for ncCR after NAT have a significantly lower rate of DM compared to patients undergoing salvage surgery after LR within WW approach. Patients managed by LE for regrowth may represent a distinct subgroup where the risk of subsequent DM is equivalent to patients managed by LE at restage.

The Estimate of the Impact of Coccyx Resection in Surgical Field Exposure During Abdominal Perineal Resection Using Preoperative High-Resolution Magnetic Resonance

OBJECTIVE

To estimate the improvement in surgical exposure by removal of the coccyx, during abdomino-perineal resection (APR), in rectal cancer patients.

METHODS

Retrospective study of 29 consecutive patients with rectal cancer was carried out. Using MR T2 sagittal series, the solid angle was estimated using the angle determined by the anterior resection margin and the tip of coccyx (no coccyx resection) or the tip of last sacral vertebra (coccyx resection). The solid angle provides an estimate of the tridimensional surface area provided by an original angle resulting in the best estimate of the surgeon's view/exposure to the critical dissecting point of choice (anterior rectal wall). The difference ("Gain") in surgical field exposure by removal of the coccyx was compared by the solid angle variation between the two estimates (with and without the coccyx).

RESULTS

Routine removal of the coccyx determines an average 42% (95% CI 27-57%) gain in surgical field exposure area facing the anterior rectal wall at the level of the prostate/vagina by the surgeon. Fifteen (51%) patients had ≥30% (median) estimated gain in surgical field exposure by coccygectomy. There was no association between BMI, age or gender and estimated gain in surgical field exposure area.

CONCLUSIONS

Routine removal of the coccyx during APR may result in an average increase in 42% in surgical field exposure during APR's perineal dissection. Precise estimation of surgical field exposure gain by removal of the coccyx may be predicted by MR sagittal series for each individual patient.