Neoadjuvant chemo-radiotherapy and rectal cancer: can the UK watch and wait with Brazil?

Stereotactic MR-guided adaptive radiotherapy (SMART) for primary rectal cancer: evaluation of early toxicity and pathological response

Background

The purpose of this study is to measure the effects of stereotactic MR-guided adaptive radiotherapy (SMART) for rectal cancer patients in terms of early toxicity and pathological response.

Materials and methods

For this prospective pilot study, patients diagnosed with locally advanced rectal cancer (LARC) with positive lymph node clinical staging underwent SMART on rectal lesion and mesorectum using hybrid MR-Linac (MRIdian ViewRay). Dose prescription at 80% isodose for the rectal lesion and mesorectum was 40 Gy (8 Gy/fr) and 25 Gy (5 Gy/fr), respectively, delivered on 5 days (3 fr/week). Response assessment by MRI was performed 3 weeks after SMART, then patients fit for surgery underwent total mesorectal excision. Primary endpoint was evaluation of adverse effect of radiotherapy. Secondary endpoint was pathological complete response rate. Early toxicity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE v5.0).

Results

From October 2020 to January 2022, twenty patients underwent rectal SMART. No grade 3-5 toxicity was recorded. Twelve patients were eligible for total mesorectal excision (TME). Mean interval between the completion of SMART and surgery was 4 weeks. Pathological downstaging occurred in all patients; rate of pathological complete response (pCR) was 17%. pCR occurred with a prolonged time to surgery (> 7 weeks).

Conclusion

To our knowledge, this is the first study to use stereotactic radiotherapy for primary rectal cancer. SMART for rectal cancer is well tolerated and effective in terms of tumor regression, especially if followed by delayed surgery.

Neoadjuvant Therapy and Surgery in Rectal Adenocarcinoma: Analysis of Patients with Complete Tumor Remission

Introduction: the standard treatment for locally advanced extra-peritoneal rectal adenocarcinoma, consists of neoadjuvant treatment with radiotherapy and chemotherapy followed by total mesorectal excision.

Objective: evaluate, retrospectively, the patients submitted to neoadjuvant therapy and surgery that presents with total remission of the lesion in the anatomopathological examination.

Methods: between 2000 and 2010, 212 patients underwent surgery at the Coloproctology Unit at DMAD at FCM–UNICAMP. They were grouped as: rectosigmoidectomy and colorectal anastomosis (n = 54), rectosigmoidectomy with coloanal anastomosis (n = 41), 114 abdominoperineal resection of the rectum (n = 114) and other (n = 3).

Results: thirty (14.2%) patients (mean age 57.6 years; 60% males) showed complete remission of the rectal lesion. 4 (13.3%) had compromised lymph nodes and/or lymphatic invasion

At follow-up (mean 51.9 months), 4 (13.3%) presented with local recurrence (one patient) or distant metastases (two patients had liver metastasis, one had liver and lung, and one had bone metastasis). The mean survival was 86.7%.

Conclusion: patients with a complete tumor response show ed an increased survival rate, however, the same patients without evidence of residual tumors could develop local recurrence or distant metastases on a later follow-up.

Adaptive radiation dose escalation in rectal adenocarcinoma: a review

Total mesorectal excision (TME) after neoadjuvant chemoradiotherapy (CRT) has offered superior control for patients with locally advanced rectal cancer, but can carry a quality of life cost. Fortunately, some patients achieve a complete response after CRT alone without the added morbidity caused by surgery. Efforts to increase fidelity of radiation treatment planning and delivery may allow for escalated doses of radiotherapy (RT) with limited off-target toxicity and elicit more pathological complete responses (pCR) to CRT thereby sparing more rectal cancer patients from surgery. In this review, methods of delivering escalated RT boost above 45-50.4 Gy are discussed including: 3D conformal, intensity-modulated radiotherapy (IMRT), and brachytherapy. Newly developed adaptive boost strategies and imaging modalities used in RT planning and response evaluation such as magnetic resonance imaging (MRI) and positron emission tomography (PET) are also discussed.

NEOADJUVANT THERAPY AND SURGERY FOR RECTAL CANCER. Comparative study between partial and complete pathological response

BACKGROUND

The approach of locally advanced extra-peritoneal rectal adenocarcinoma implies a treatment with neoadjuvant chemoradiotherapy associated with total mesorectal excision surgery. However, the tumors respond variably to this neoadjuvant therapy, and the mechanisms for response are not completely understood.

OBJECTIVE

Evaluate the variables related to the complete tumor response and the outcomes of patients who underwent surgery, comparing those with partial tumor regression and those with total remission of rectal lesion, at the pathological examination.

METHODS

Retrospective analysis of medical records of 212 patients operated between 2000 and 2010, in which 182 (85.9%) obtained partial remission at neoadjuvant therapy (Group 1) and 30 (14.1%), total remission (Group 2).

RESULTS

No difference was found between the groups in relation to gender, ethnicity, age, tumor distance from the anal verge, occurrence of metastases and synchronous lesions on preoperative staging, dose of radiotherapy and performed surgery. In Group 2, was verified high rate of complete remission when the time to surgery after neoadjuvant therapy was equal or less than 8 weeks (P=0.027), and a tendency of lower levels of pretreatment carcinoembryonic antigen (P=0.067). In pathological analysis, the Group 1 presented in relation to Group 2, more affected lymph nodes (average 1.9 and 0.5 respectively; P=0.003), more angiolymphatic (19.2% and 3.3%; P=0.032) and perineural involvement (15.4% and 0%; P=0.017) and greater number of lymph nodes examined (16.3 and 13.6; P=0.023). In the late follow-up, Group 1 also had lower overall survival than Group 2 (94.1 months and 136.4 months respectively; P=0.02) and disease-free survival (85.5 months and 134.6 months; P=0.004). There was no statistical difference between Group 2 and Group 1 in local recurrence (15% and 3.4%, respectively) and distant metastasis (28% and 13.8%, respectively).

CONCLUSION

In this study, the only factor associated with complete remission of rectal adenocarcinoma was the time between neoadjuvant therapy and surgery. This group of patients had less affected lymph nodes, less angiolymphatic and perineural involvement, a longer overall and disease-free survival, but no significant statistical difference was observed in local recurrence and distant metastasis. Although the complete pathologic remission was associated with better prognosis, this not implied in the cure of the disease for all patients.

Utility of rectoscopy in the assessment of response to neoadjuvant treatment for locally advanced rectal cancer

BACKGROUND/AIMS

The management of locally advanced rectal cancer has changed substantially over the last few decades with neoadjuvant chemoradiotherapy. The aim of the present study is to compare the results between neoadjuvant post-treatment rectoscopy and the anatomopathological findings of the surgical specimen.

PATIENTS AND METHODS

We conducted a prospective study of 67 patients with locally advanced adenocarcinoma of the rectum (stages II and III). Two groups were established: One with complete clinical response (cCR) and one without (non-cCR), based on the findings at rectoscopy. Assessment of tumor regression grade in the surgical specimen was determined using Mandard's tumor regression scale.

RESULTS

Seventeen patients showed a cCR. Thirty-five biopsies were negative and 32 were positive for malignancy. All the cCR patients had a negative biopsy (P < 0.0001). All 32 positive biopsies revealed the presence of adenocarcinoma, and of the 35 negative biopsies, 18 had no malignancy and 17 were diagnosed with adenocarcinoma (P < 0.0001). Sixteen of the 17 cCR patients showed a complete pathological response and one patient showed the presence of adenocarcinoma. Of the 50 non-cCR patients 48 revealed the presence of adenocarcinoma and two had absence of malignancy. According to the Mandard classification, 16 of the 17 cCR patients were grade I and 1 grade II; 2 non-cCR patients were grade I, 7 grade II, 13 grade III, 19 grade IV, and 9 grade V.

CONCLUSIONS

Endoscopic and histological findings could be determinants in the assessment of response to neoadjuvant treatment.

Can We Predict Complete or Major Response after Chemoradiotherapy for Rectal Cancer by Noninvasive Methods? Results of a Prospective Study on 61 Patients

Rectal preservation has been proposed as an alternative to radical resection in patients with presumed complete or major response to chemoradiotherapy (CRT). The aim of this prospective study was to evaluate the accuracy of digital rectal examination (DRE) and magnetic resonance imaging (MRI) to predict major or complete rectal cancer response to CRT. Over 2 years, 61 patients underwent radical resection after CRT for rectal cancer. DRE and MRI were carried out before and 6 to 8 weeks after the end of CRT. Data from DRE and MRI post-CRT were compared with pathological examinations. At pathological examination, major/complete responses were recorded for tumors classified ypT1N0 and ypT0N0, respectively. DRE post-CRT showed major/complete response in 26 cases, of which 14 (54%) were confirmed by pathology. The positive (PPV) and negative (NPV) predictive values of DRE to predict major/complete response were 54 and 88 per cent, respectively. MRI post-CRT showed major/complete response in 12 cases, of which nine (75%) were confirmed by pathology. The PPV and NPV of MRI to predict major/complete response were 75 and 82 per cent, respectively. Data from DRE and RMI post-CRT were concordant in 45 patients. The PPV and NPV of concordant DRE and MRI to predict major/complete response were 82 and 91 per cent, respectively. DRE and MRI do not appear to be sufficiently accurate for safe selection of patients appropriate for a rectum-sparing strategy because the risk of leaving an invasive tumor untreated is 18 per cent.

Evolving treatment strategies for colorectal cancer: A critical review of current therapeutic options

Management of rectal cancer has markedly evolved over the last two decades. New technologies of staging have allowed a more precise definition of tumor extension. Refinements in surgical concepts and techniques have resulted in higher rates of sphincter preservation and better functional outcome for patients with this malignancy. Although, preoperative chemoradiotherapy followed by total mesorectal excision has become the standard of care for locally advanced tumors, many controversial matters in management of rectal cancer still need to be defined. These include the feasibility of a non-surgical approach after a favorable response to neoadjuvant therapy, the ideal margins of surgical resection for sphincter preservation and the adequacy of minimally invasive techniques of tumor resection. In this article, after an extensive search in PubMed and Embase databases, we critically review the current strategies and the most debatable matters in treatment of rectal cancer.

Future directions for monitoring treatment response in colorectal cancer

Treatment of advanced colon and rectal cancer has significantly evolved with the introduction of neoadjuvant chemoradiation therapy so much that, along with more effective chemotherapy regimens, surgery has been considered unnecessary among some institutions for select patients. The tumor response to these treatments has also improved and ultimately has been shown to have a direct effect on prognosis. Yet, the best way to monitor that response, whether clinically, radiologically, or with laboratory findings, remains controversial. The authors' aim is to briefly review the options available and, more importantly, examine emerging and future options to assist in monitoring treatment response in cases of locally advanced rectal cancer and metastatic colon cancer.

Risk factors for local recurrence following neoadjuvant chemoradiotherapy for rectal cancers

Local recurrence (LR) has an adverse impact on rectal cancer treatment. Neoadjuvant chemoradiotherapy (nCRT) is increasingly administered to patients with progressive cancers to improve the prognosis. However, LR still remains a problem and its pattern can alter. Correspondingly, new risk factors have emerged in the context of nCRT in addition to the traditional risk factors in patients receiving non-neoadjuvant therapies. These risk factors are decisive when reviewing treatment options. This review aims to elucidate the distinctive risk factors related to LR of rectal cancers in patients receiving nCRT and to clarify their clinical significance. A search was conducted on PubMed to identify original studies investigating patients with rectal cancer receiving nCRT. Outcomes of interest, especially potential risk factors for LR in patients with nCRT, were then analyzed. The clinical importance of these risk factors is discussed. Remnant cancer cells, lymph-nodes and tumor response were found to be major risk factors. Remnant cancer cells decide the status of resection margins. Local excision following nCRT is promising in ypT0-1N0M0 cases. Dissection of lateral lymph nodes should be considered in advanced low-lying cancers. Although better tumor response resulted in a relatively lower recurrence rate, the evidence available is insufficient to justify a non-operative approach in clinical complete responders to nCRT. LR cannot be totally avoided by current multidisciplinary approaches. The related risk factors resulting from nCRT should be considered when making decisions regarding treatment selection.

Critical appraisal of the 'wait and see' approach in rectal cancer for clinical complete responders after chemoradiation

BACKGROUND

Some 10-20 per cent of patients with locally advanced rectal cancer achieve a pathological complete response (pCR) at surgery following preoperative chemoradiation (CRT). Some demonstrate a sustained clinical complete response (cCR), defined as absence of clinically detectable residual tumour after CRT, and do not undergo resection. The aim of this review was to evaluate non-operative treatment of rectal cancer after CRT, and the outcome of patients observed without radical surgery.

METHODS

A systematic computerized search identified 30 publications (9 series, 650 patients) evaluating a non-operative approach after CRT. Original data were extracted and tabulated, and study quality evaluated. The primary outcome measure was cCR. Secondary outcome measures included locoregional failure rate, disease-free survival and overall survival.

RESULTS

The most recent Habr-Gama series reported a low locoregional failure rate of 4·6 per cent, with 5-year overall and disease-free survival rates of 96 and 72 per cent respectively. These findings were supported by a small prospective Dutch study. However, other retrospective series have described higher recurrence rates. All studies were heterogeneous in staging, inclusion criteria, study design and rigour of follow-up after CRT, which might explain the different outcomes. The definition of cCR was inconsistent, with only partial concordance with pCR. The results suggested that patients who are observed, but subsequently fail to sustain a cCR, may fare worse than those who undergo immediate tumour resection.

CONCLUSION

The rationale of a 'wait and see' policy relies mainly on retrospective observations from a single series. Proof of principle in small low rectal cancers, where clinical assessment is easy, should not be extrapolated uncritically to more advanced cancers where nodal involvement is common. Long-term prospective observational studies with more uniform inclusion criteria are required to evaluate the risk versus benefit.

Preoperative treatment does not improve the therapeutic results of abdominosacral amputation of the rectum

BACKGROUND

This study reviewed the impact of preoperative chemoradiotherapy/short-term radiotherapy on abdominosacral amputations of the rectum (ASAR) for the treatment of low-rectum cancers in terms of postoperative morbidity, local recurrence rates, and survival.

METHODS

A total of 198 patients with stage II and III tumors located within 6 cm of the anorectal junction underwent ASAR between 1998 and 2008 and were selected for further analysis. Patients were compared according to the following groups: those who had surgery only (Group A) and those who had preoperative chemoradiotherapy/short-term radiotherapy (Group B).

RESULTS

There were 44 and 154 patients in Groups A and B, respectively, including 135 males. The median age of the subjects was 63 years (range = 35-88). The median follow-up period was 81 months (range = 23-138). Neither the local recurrence rates (6.8% in Group A vs. 4.6% in Group B, p = 0.544) nor the 5-year relative survival rates (72.4% in Group A vs. 69.3% in Group B, p = 0.127) differed significantly between the groups.

CONCLUSION

Preoperative therapy in low-rectum cancer does not improve the therapeutic results of ASAR.

Combination of differentiation and T stage can predict unresponsiveness to neoadjuvant therapy for rectal cancer

AIM

The study aimed to identify the factors predictive for extreme unresponsiveness to neoadjuvant therapy for rectal cancer.

METHOD

Ninety-six patients with rectal cancer received neoadjuvant therapy (41 were treated with radiotherapy and 55 with chemoradiotherapy) before surgery. Tumour response, downstaging, pathological complete response (pCR) and disease-free survival were evaluated.

RESULTS

Tumour response, downstaging and pCR occurred in 70 (72.9%), 47 (49.0%) and 14 (14.6%) patients, respectively. Univariate analyses showed that a large tumour size, T4 stage, elevated serum tumour markers, poor differentiation, radiotherapy alone and mucinous tumour were indicators of poor tumour response and/or downstaging. On multivariate analysis, chemoradiotherapy was found to be predictive for tumour response and downstaging, whereas mucinous type and T4 stage negatively affected tumour response. No variable was found to be associated with pCR, but poor differentiation and T4 stage together predicted extreme unresponsiveness with a high specificity and a high positive predictive value. Very poor disease-free survival was also observed in patients simultaneously carrying these phenotypes.

CONCLUSION

Neoadjuvant chemoradiotherapy is superior to radiotherapy alone in producing a response of rectal cancer. Unresponsiveness was most likely to occur in patients with poor differentiation and T4 disease.