The 2017 Assisi Think Tank Meeting on rectal cancer: A positioning paper

BACKGROUND AND PURPOSES

To describe current practice in the management of rectal cancer, to identify uncertainties that usually arise in the multidisciplinary team (MDT)'s discussions ('grey zones') and propose next generation studies which may provide answers to them.

MATERIALS AND METHODS

A questionnaire on the areas of controversy in managing T2, T3 and T4 rectal cancer was drawn up and distributed to the Rectal-Assisi Think Tank Meeting (ATTM) Expert European Board. Less than 70% agreement on a treatment option was indicated as uncertainty and selected as a 'grey zone'. Topics with large disagreement were selected by the task force group for discussion at the Rectal-ATTM.

RESULTS

The controversial clinical issues that had been identified within cT2-cT3-cT4 needed further investigation. The discussions focused on the role of (1) neoadjuvant therapy and organ preservation on cT2-3a low-middle rectal cancer; (2) neoadjuvant therapy in cT3 low rectal cancer without high risk features; (3) total neoadjuvant therapy, radiotherapy boost and the best chemo-radiotherapy schedule in T4 tumors. A description of each area of investigation and trial proposals are reported.

CONCLUSION

The meeting successfully identified 'grey zones' and, in the light of new evidence, proposed clinical trials for treatment of early, intermediate and advanced stage rectal cancer.

Review of Neoadjuvant Chemotherapy Alone in Locally Advanced Rectal Cancer

BACKGROUND

Currently, the standard management of locally advanced rectal cancer (LARC) is neoadjuvant chemoradiotherapy followed by resection. Despite the significant improvement in local recurrence, survival benefits are not gained due to distant failure and radiotherapy-associated toxicity. Compliance to adjuvant chemotherapy after preoperative chemoradiotherapy is also poor. Neoadjuvant chemotherapy alone followed by surgery may be an alternative. The objective of this review is to determine the efficacy of neoadjuvant chemotherapy alone in operable LARC.

MATERIALS AND METHODS

Electronic databases searched (from database inception-December 2013) were Medline, PubMed, Embase, Scopus, Cochrane library, and the Clinical Trials Register. Specific journals were also hand searched. The selection criteria were studies published in English investigating stage II-III non-metastatic rectal cancer patients treated with neoadjuvant chemotherapy (oral, intravenous or rectal route) followed by curative resection. The primary outcome measure was tumour response. Secondary outcome measures included acute toxicity, operative morbidity, R0 resection, local recurrence, overall survival (OS) and disease-free survival (DFS).

RESULTS

One randomised phase III trial, six single-arm phase II trials and one retrospective case series study were eligible for inclusion. Six studies administered fluoropyrimidine-based multiple agent regimens and two studies administered fluorouracil-based monotherapy. The studies with multiple agents and stronger chemotherapy regimens (intravenous and/or oral) followed by delayed surgery showed better tumour response rates. The overall objective response rate was good and ranged from 62.5 to 93.7 %. Pathological complete response ranged from 3.8 to 33.3 %. The R0 resection and compliance rates were also high ranging from 90 to 100 % and 72 to 100 %, respectively. Grade 3-4 toxicities ranged from 2.3 to 39 %. Four- to 5-year OS and DFS ranged from 67.2 to 91 % and 60.5 to 84 %, respectively.

CONCLUSION

This review demonstrates that neoadjuvant chemotherapy could be affectively administered in LARC and could provide a good alternative to chemoradiotherapy in moderate-risk rectal cancers without compromising short- and long-term outcomes.

Bevacizumab and Combination Chemotherapy in rectal cancer Until Surgery (BACCHUS): a phase II, multicentre, open-label, randomised study of neoadjuvant chemotherapy alone in patients with high-risk cancer of the rectum

BACKGROUND

In locally advanced rectal cancer (LARC) preoperative chemoradiation (CRT) is the standard of care, but the risk of local recurrence is low with good quality total mesorectal excision (TME), although many still develop metastatic disease. Current challenges in treating rectal cancer include the development of effective organ-preserving approaches and the prevention of subsequent metastatic disease. Neoadjuvant systemic chemotherapy (NACT) alone may reduce local and systemic recurrences, and may be more effective than postoperative treatments which often have poor compliance. Investigation of intensified NACT is warranted to improve outcomes for patients with LARC. The objective is to evaluate feasibility and efficacy of a four-drug regimen containing bevacizumab prior to surgical resection.

METHODS/DESIGN

This is a multi-centre, randomized phase II trial. Eligible patients must have histologically confirmed LARC with distal part of the tumour 4-12 cm from anal verge, no metastases, and poor prognostic features on pelvic MRI. Sixty patients will be randomly assigned in a 1:1 ratio to receive folinic acid + flurourcil + oxaliplatin (FOLFOX) + bevacizumab (BVZ) or FOLFOX + irinotecan (FOLFOXIRI) + BVZ, given in 2 weekly cycles for up to 6 cycles prior to TME. Patients stop treatment if they fail to respond after 3 cycles (defined as ≥ 30 % decrease in Standardised Uptake Value (SUV) compared to baseline PET/CT). The primary endpoint is pathological complete response rate. Secondary endpoints include objective response rate, MRI tumour regression grade, involved circumferential resection margin rate, T and N stage downstaging, progression-free survival, disease-free survival, overall survival, local control, 1-year colostomy rate, acute toxicity, compliance to chemotherapy.

DISCUSSION

In LARC, a neoadjuvant chemotherapy regimen - if feasible, effective and tolerable would be suitable for testing as the novel arm against the current standards of short course preoperative radiotherapy (SCPRT) and/or fluorouracil (5FU)-based CRT in a future randomised phase III trial.

TRIAL REGISTRATION

Clinical trial identifier BACCHUS: NCT01650428.

Multidisciplinary Management of Locally Advanced Rectal Cancer--An Evolving Landscape?

For many years, the multidisciplinary approach of neoadjuvant radiotherapy with or without concurrent chemotherapy followed by total mesorectal excision and adjuvant fluoropyrimidine chemotherapy has remained the accepted standard management for locally advanced rectal cancers. Over this time period, many new systemic treatment options have become available, including: additional chemotherapeutic agents (oxaliplatin) and targeted therapies (vascular endothelial growth factor and epidermal growth factor receptor inhibitors), which can be added to neoadjuvant and adjuvant regimens or given in combination with radiotherapy as radio-sensitizing agents. Here we review the current literature, examining emerging data related to the impact of multiple modifications to the standard approach, including the role of neoadjuvant chemotherapy, the addition of new agents to standard chemoradiation, and postoperative fluoropyrimidine-based treatment, the optimal timing of surgery, and nonoperative approaches to the management of locally advanced rectal cancers.

Neoadjuvant chemotherapy without radiotherapy for locally advanced rectal cancer

ABSTRACT 

Chemoradiotherapy or short-course radiotherapy followed by surgery is a standard treatment for locally advanced rectal cancer. This multimodality strategy has reduced the risk of local recurrence but failed to improve survival. Moreover, mid- and long-term side effects of radiotherapy have been reported. Alternative strategies have been investigated in an attempt to minimize treatment-related toxicities and improve outcome. Neoadjuvant chemotherapy without radiotherapy is an attractive therapeutic option that yields theoretical advantages. Moreover, if carefully selected, patients may be spared the effects of radiotherapy without compromising the oncology outcome. The authors review the available evidence on neoadjuvant chemotherapy without radiotherapy in locally advanced rectal cancer and try to anticipate potential algorithms of treatment selection to implement in clinical practice in the future.

Neoadjuvant capecitabine and oxaliplatin (XELOX) combined with bevacizumab for high-risk localized rectal cancer

PURPOSE

Chemoradiotherapy followed by total mesorectal excision (TME) is the standard treatment for locally advanced rectal cancer. Although this approach decreases the risk of local recurrence, pelvic radiation is associated with long-term morbidity and delays systemic treatment. We conducted this study to evaluate the feasibility of neoadjuvant capecitabine and oxaliplatin (XELOX) plus bevacizumab as a treatment for high-risk localized rectal cancer.

METHODS

Patients with T4 or lymph node-positive rectal cancer were treated with three cycles of XELOX plus bevacizumab and one additional cycle of XELOX. This was followed by TME performed 3-8 weeks after the last chemotherapy session.

RESULTS

Twenty-five patients were recruited between December 2009 and November 2011. In seven of the patients (28.0 %), grade 3-4 adverse events occurred. After preoperative chemotherapy, the frequency of tumor (T) downstaging was 69.6 %, and that of lymph node (N) downstaging was 78.9 %. Seven patients discontinued the treatment after 2-3 cycles of XELOX plus bevacizumab. The frequency of subsequent surgery was 92 %, and all patients underwent R0 resections. Postoperative complications occurred in six patients (26.1 %). One patient achieved a pathological complete response (pCR) for the primary tumor and lymph nodes, whereas an additional four patients achieved near-pCR. After a median follow-up of 31 months, five patients displayed metastatic progression, including one who suffered local recurrence.

CONCLUSIONS

XELOX plus bevacizumab followed by TME is feasible for high-risk localized rectal cancer, as it achieves good tumor regression and causes manageable toxicity.

MRI and FDG-PET for assessment of response to neoadjuvant chemotherapy in locally advanced rectal cancer

BACKGROUND

The purpose of this study was to assess the value of magnetic resonance imaging (MRI) and additional (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for tumor response to neoadjuvant chemotherapy (NAC) in patients with locally advanced rectal cancer (LARC).

METHODS

Data on 40 patients with LARC, who were treated with NAC and underwent MRI and FDG-PET/CT before and after NAC, were analyzed retrospectively. Surgery was performed at a median of 6 weeks after NAC and the images were compared with the histological findings. The tumor regression grade 3/4 was classified as a responder.

RESULTS

Sixteen patients were pathological responders. Receiver operating characteristic (ROC) analysis revealed that MRI total volume after NAC (MRI-TV2) and ΔMRI-TV had the highest performance to assess responders (area under the ROC curve [AUC] 0.849 and AUC 0.853, respectively). The reduction rate of the maximum standardized uptake value (ΔSUVmax) was also an informative factor (AUC 0.719). There seems no added value of adding FDG-PET/CT to MRI-TV2 and ΔMRI-TV in assessment of NAC responders judging from changes in AUC (AUC of ΔSUVmax and MRI-TV2 was 0.844, and AUC of ΔSUVmax and ΔMRI-TV was 0.846).

CONCLUSIONS

MRI-TV2 and ΔMRI-TV were the most accurate factors to assess pathological response to NAC. Although ΔSUVmax by itself was also informative, the addition of FDG-PET/CT to MRI did not improve performance. Patients with LARC who were treated by induction chemotherapy should receive an MRI examination before and after NAC to assess treatment response. A more than 70 % volume reduction shown by MRI volumetry may justify the omission of subsequent radiotherapy.

Do t3 rectal cancers always need radiochemotherapy?

The limitation of the traditional method of stratifying patients with rectal cancer for prognosis using magnetic resonance imaging (MRI) and computerised tomography (CT)-TNM staging-is that cT3 tumors comprise the vast majority of rectal cancers. There is a wide variability in outcomes for cT3. Despite this observation, many still advocate routine short course preoperative radiotherapy (SCPRT) or chemoradiation (CRT) for all patients staged as cT3N0 regardless of tumour location, proximity to other structures or extent, despite the fact that advances in imaging with MRI now offer the ability to predict potential outcomes in terms of the risk of local and metastatic recurrence for the individual. Preoperative CRT is designed to reduce local recurrence. The majority of local recurrences historically reflected inadequate quality of the mesorectal resection. Currently, optimal quality-controlled surgery in terms of total mesorectal excision (TME) in the trial setting can be associated with much lower local recurrence rates of less than 10 % whether patients receive radiotherapy or not. Because of the high risk of metastatic disease in selected patients, integrating more active chemotherapy is now attractive. Chemoradiotherapy (CRT) achieves shrinkage and sometimes eradication of tumour-i.e. a pathological complete response (pCR), and reduces local recurrence, but has no impact on overall survival. CRT also increases surgical morbidity and impacts on anorectal, urinary and sexual function with an increased risk of second malignancies. Hence, the predominant aims of CRT have been to shrink/downstage a tumour to allow an R0 resection to be performed, or to increase the chances of performing sphincter-sparing surgery. However, it remains unclear why shrinkage/downstaging is meaningful to a patient unless the tumour is initially borderline resectable or unresectable (i.e. the CRM is threatened) or the aim is to perform a lesser operation (i.e. sphincter-sparing or local excision) or for organ-sparing, i.e. to avoid surgery altogether. If it is important to shrink the cancer-ie there is a predicted threat to the CRM, then CRT is currently the treatment of choice. If the cancer is resectable and the aim is simply to lower the risk of local recurrence and preoperative CRT does not impact on survival, can CRT be omitted in selected cases? The answer is yes-with the proviso that we are using good quality MRI and the surgeon is performing good quality TME surgery within the mesorectal plane.

Postoperative complications following neoadjuvant bevacizumab treatment for advanced colorectal cancer

PURPOSES

Attempts have been made to use bevacizumab (BEV) in an adjuvant or neoadjuvant setting. However, BEV is known to cause various adverse events, and the safety of neoadjuvant BEV has not yet been fully evaluated. This study assessed the postoperative complications in patients receiving neoadjuvant BEV for colorectal cancer.

METHODS

The data for 78 patients with resectable advanced or metastatic colorectal cancer who received neoadjuvant BEV followed by surgical resection were retrospectively analyzed.

RESULTS

The median interval between the last BEV dose and surgery was 9 weeks. The most common postoperative complication was pelvic sepsis, which occurred in 11 patients (14 %). A biliary fistula developed in four of 23 patients who underwent liver resection. Anastomotic leakage occurred in six of 24 patients with a colorectal anastomosis, four of whom required re-laparotomy. In a univariate analysis, male gender and a greater intraoperative blood loss were associated with postoperative complications of any grade. Colorectal anastomosis was a risk factor for major complications. In a multivariate analysis, intraoperative blood loss was an independent risk factor for postoperative complications of any grade (HR 6.338; P = 0.003). With regard to major postoperative complications, colorectal primary anastomosis was the only independent predictive risk factor (HR 8.285; P = 0.013).

CONCLUSIONS

In patients with colorectal cancer who underwent elective surgery after BEV treatment, the interval between BEV and surgery was not a risk factor for postoperative complications (based on a median interval of 9 weeks). Colorectal primary anastomosis was the only independent risk factor for major postoperative complications.

Selecting patients with locally advanced rectal cancer for neoadjuvant treatment strategies

Rectal cancer remains a significant problem worldwide. Outcomes vary significantly according to the stage of disease and prognostic factors, including the distance of the tumor from the circumferential resection margin. Accurate staging, including high-resolution magnetic resonance imaging, allows stratification of patients into low-, moderate-, and high-risk disease; this information can be used to inform multidisciplinary team decisions regarding the role of neoadjuvant therapy. Both neoadjuvant short-course radiotherapy and long-course chemoradiation reduce the risk of local recurrence compared with surgery alone, but they have little impact on survival. Although there remains a need to reduce overtreatment of those patients at moderate risk, evaluation of intensified regimens for those with high-risk disease is still required to reduce distant failure rates and improve survival in these patients with an otherwise poor prognosis.

Clinically relevant study end points in rectal cancer

In rectal cancer currently there are no clearly validated early end points which can serve as surrogates for long-term clinical outcome such as local control and survival. However, the use of a variety of response rates (i.e. pathological complete response, downsizing the primary tumor, tumor regression grade (TRG), radiological response) as endpoints in early (phase II) clinical trials is common since objective response to therapy is an early indication of activity. Disease-free survival (DFS) has been proposed as the most appropriate end point in adjuvant trials and is one of the most frequently used in newer rectal cancer trials. Due to the devastating nature of local recurrence in locally advanced rectal cancer, local control (which is itself a subset of the overall DFS endpoint) is still considered an important endpoint. Recently, circumferential resection margin (CRM) has been proposed as novel early end point because the CRM status can account for effects on DFS and overall survival after chemoradiation, radiation (RT), or surgery alone. Consensus is needed to define the most appropriate end points in both early and phase III trials in locally advanced cancer.