Accuracy of positron emission tomography/computed tomography and clinical assessment in the detection of complete rectal tumor regression after neoadjuvant chemoradiation: long-term results of a prospective trial (National Clinical Trial 00254683)

Consolidation chemotherapy during neoadjuvant chemoradiation (CRT) for distal rectal cancer leads to sustained decrease in tumor metabolism when compared to standard CRT regimen

Background

Neoadjuvant CRT may lead to significant tumor regression in patients with rectal cancer. Different CRT regimens with consolidation chemotherapy may lead to increased rates of complete tumor regression. The purpose of this study was to understand tumor metabolic activity following two different neoadjuvant CRT regimens using sequential PET/CT imaging in two different intervals following RT.

Methods

Patients with cT2-4 N0-2 M0 rectal cancer treated by standard CRT (54Gy and 2 cycles of 5FU-based chemotherapy) or extended CRT (54Gy and 6 cycles of 5FU-based chemotherapy) underwent sequential PET/CT imaging at baseline, 6 weeks and 12 weeks from radiation completion.

Results

99 patients undergoing standard CRT were compared to 12 patients undergoing CRT with consolidation chemotherapy. Patients treated with consolidation CRT had increased rates of complete clinical or pathological response (66 % vs. 23 %; p < 0.001). SUVmax variation between baseline and 6 weeks (88 % vs. 63 %; p < 0.001) and between baseline and 12 weeks (90 % vs. 57 %; p < 0.001) were significantly more pronounced among patients undergoing extended CRT with consolidation chemotherapy. An increase in SUVmax between 6 and 12 weeks was observed in 51 % of patients undergoing standard and 18 % of patients undergoing consolidation CRT (p = 0.04).

Conclusions

Most of the reduction in tumor metabolism after neoadjuvant CRT occurs within the first 6 weeks from RT completion. In patients undergoing CRT with consolidation chemotherapy, tumors are less likely to regain metabolic activity between 6 and 12 weeks. Therefore, assessment of tumor response may be safely postponed to 12 weeks in patients undergoing extended CRT with consolidation chemotherapy.

Trial registration

NCT00254683

Predictors of Complete Response and Disease Recurrence Following Chemoradiation for Rectal Cancer

OBJECTIVE

Approximately 10-40% of rectal patients have a complete response (CR) to neoadjuvant chemoradiation (CRT), and these patients have improved survival. Thus, non-operative management ("watch-and-wait" approach) may be an option for select patients. We aimed to identify clinical predictors of CR following CRT.

METHODS

Patients treated with definitive CRT for T3-T4, locally unresectable T1-T2, low-lying T2, and/or node-positive rectal cancer from August 2004 to February 2015 were retrospectively reviewed. Most patients were treated with 50.4 Gy radiation and concurrent 5-fluoruracil or capecitabine. Patients were considered to have a CR if surgical pathology revealed ypT0N0M0 (operative management), or if they had no evidence of residual disease on clinical and radiographic assessment (non-operative management). Statistical analysis was carried out to determine predictors of CR and long-term outcomes.

RESULTS

Complete records were available on 138 patients. The median follow-up was 24.5 months. Thirty-six patients (26.3%) achieved a CR; 30/123 operatively managed patients (24.5%) and 6/15 (40%) non-operatively managed patients. None of the 10 patients with mucinous adenocarcinoma achieved a CR. Carcinoembryonic antigen (CEA) ≥5 μg/L at diagnosis (OR 0.190, 95% CI 0.037-0.971, p = 0.046), tumor size ≥3 cm (OR 0.123, 95% CI 0.020-0.745, p = 0.023), distance of tumor from the anal verge ≥3 cm (OR 0.091, 95% CI 0.013-0.613, p = 0.014), clinically node-positive disease at diagnosis (OR 0.201, 95% CI 0.045-0.895, p = 0.035), and interval from CRT to surgery ≥8 weeks (OR 5.267, 95% CI 1.068-25.961, p = 0.041) were independent predictors of CR. The CR group had longer 3-year distant metastasis-free survival (DMFS) (93.7 vs. 63.7%, p = 0.016) and 3-year disease-free survival (DFS) (91.1 vs. 67.8%, p = 0.038). Three-year locoregional control (LRC) (96.6 vs. 81.3%, p = 0.103) and overall survival (97.2 vs. 87.5%, p = 0.125) were higher in the CR group but this did not achieve statistical significance. CR was not an independent predictor of LRC, DMFS, or DFS.

CONCLUSION

CEA at diagnosis, tumor size, tumor distance from the anal verge, node positivity at diagnosis, and interval from CRT to surgery were predictors of CR. These clinical variables may offer insight into patient selection and timing of treatment response evaluation in the watch-and-wait approach.

Optimal therapy for resectable rectal cancer

A lot can be gained by improving our understanding of the optimal sequence of existing therapies in rectal cancer, with the more difficult task of balancing the morbidity of recurrence with the morbidity of prescribed therapies that are particularly toxic owing to tumour location. This review aims to highlight a recent shift in treatment strategies in the opposite direction, with a focus on earlier, more intense systemic treatments with reduced local therapies. Understanding the rationale for and evidence to support this shift will help identify gaps, shape future trials, and ultimately answer the question of whether this is indeed the right path to follow with regards to maintaining local control rates and long-term outcomes for patients, and improving distal disease control and local treatment-related morbidities without compromising quality of life.

Neoadjuvant chemoradiation therapy and pathological complete response in rectal cancer

The management of rectal cancer has evolved significantly in the last few decades. Significant improvements in local disease control were achieved in the 1990s, with the introduction of total mesorectal excision and neoadjuvant radiotherapy. Level 1 evidence has shown that, with neoadjuvant chemoradiation therapy (CRT) the rates of local recurrence can be lower than 6% and, as a result, neoadjuvant CRT currently represents the accepted standard of care. This approach has led to reliable tumor down-staging, with 15-27% patients with a pathological complete response (pCR)-defined as no residual cancer found on histological examination of the specimen. Patients who achieve pCR after CRT have better long-term outcomes, less risk of developing local or distal recurrence and improved survival. For all these reasons, sphincter-preserving procedures or organ-preserving options have been suggested, such as local excision of residual tumor or the omission of surgery altogether. Although local recurrence rate has been stable at 5-6% with this multidisciplinary management method, distal recurrence rates for locally-advanced rectal cancers remain in excess of 25% and represent the main cause of death in these patients. For this reason, more recent trials have been looking at the administration of full-dose systemic chemotherapy in the neoadjuvant setting (in order to offer early treatment of disseminated micrometastases, thus improving control of systemic disease) and selective use of radiotherapy only in non-responders or for low rectal tumors smaller than 5 cm.

The value of forceps biopsy and core needle biopsy in prediction of pathologic complete remission in locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy

Patients with pathological complete remission (pCR) after treated with neoadjuvant chemoradiotherapy (nCRT) have better long-term outcome and may receive conservative treatments in locally advanced rectal cancer (LARC). The study aimed to evaluate the value of forceps biopsy and core needle biopsy in prediction of pCR in LARC treated with nCRT. In total, 120patients entered this study. Sixty-one consecutive patients received preoperative forceps biopsy during endoscopic examination. Ex vivo core needle biopsy was performed in resected specimens of another 43 consecutive patients. The accuracy for ex vivo core needle biopsy was significantly higher than forceps biopsy (76.7% vs. 36.1%; p < 0.001). The sensitivity for ex vivo core needle biopsy was significantly lower in good responder (TRG 3) than poor responder (TRG ≤ 2) (52.9% vs. 94.1%; p = 0.017). In vivo core needle biopsy was further performed in 16 patients with good response. Eleven patients had residual cancer cells in final resected specimens, among whom 4 (36.4%) patients were biopsy positive. In conclusion, routine forceps biopsy was of limited value in identifying pCR after nCRT. Although core needle biopsy might further identify a subset of patients with residual cancer cells, the accuracy was not substantially increased in good responders.

Assessing pathological complete response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer: a systematic review

AIM

Pathological complete response to neoadjuvant chemoradiotherapy is found in 20% of patients with rectal cancer undergoing long-course chemoradiotherapy. Some authors have suggested that these patients do not need to undergo surgery and can be managed with careful follow-up, with surgery only used in the event of clinical failure. Widespread adoption of this regimen is limited by the accuracy of methods to confirm a pathological complete response (pCR).

METHOD

A systematic search of PubMed, Medline and Cochrane databases was conducted to identify clinical, histological and radiological features in those patients with rectal cancer who achieved a pCR following chemoradiotherapy. Searches were conducted with the following keywords and MeSH search terms: 'rectal neoplasm', 'response', 'neoadjuvant', 'preoperative chemoradiation' and 'tumour response'. After review of title and abstracts, 89 articles addressing the assessment of pCR were identified.

RESULTS

Histology and clinical assessment are the most effective methods of assessment of pCR, with histology considered the gold standard. Clinical assessment is limited to low rectal tumours and is open to significant inter-rater variability, while histological examination requires a surgical specimen. Diffusion-weighted MRI and (18) F-fluorodeoxyglucose positron emission tomography/CT demonstrate the greatest potential for the assessment of pCR, but both modalities have limited accuracy.

CONCLUSION

Determination of a pCR is crucial if a nonoperative approach is to be undertaken proactively. Various methods are available, but currently they lack sufficient sensitivity and specificity to define management. This is likely to be an area of further research in the future.

[Organ preserving strategies for rectal cancer treatment]

For rectal cancers, the current standard of care consists of chemoradiation followed by radical surgery with total mesorectal excision. Oncologic results are good, especially regarding local recurrence rates, but at the cost of high morbidity rates and poor anorectal, urinary and sexual function results. Since chemoradiation yields 15 to 25% pathological complete response, the role of radical surgery is questioned for patients presenting with good response after chemoradiation and two organ preservation strategies have been offered: watch and wait strategy and local excision strategy. The aim of this review is to give the results of organ preservation after chemoradiotherapy series and to highlight different questions regarding initial patient's selection, complete clinical response definition, risk of mesorectal nodal involvement, follow-up modalities as well as oncologic and functional results.

Surgeon perspectives on the use and effects of neoadjuvant chemoradiation in the treatment of rectal cancer: a comprehensive review of the literature

BACKGROUND

Despite screening initiatives, rectal cancer remains one of the most prevalent malignancies diagnosed in patients worldwide with a high mortality. The introduction of neoadjuvant therapy has resulted in a paradigm shift in the treatment and outcomes of rectal cancer. Surgeons play an intricate role in the pre-operative, operative, and post-operative management of these patients.

PURPOSE

The purpose of this comprehensive literature review was to summarize the evolution of the use chemotherapy and radiation and the process of differentiation into specific neoadjuvant chemoradiation protocols in the treatment of locally advanced rectal cancer. This will provide a concise summary for practicing surgeons of the current evidence for neoadjuvant chemoradiation as well as the various implications of therapy on operative outcomes.

CONCLUSION

The initial benefit of adjuvant therapy in the treatment of rectal cancer patients became evident with prospective studies demonstrating improvements in various oncologic survival outcomes. Due to the improved compliance and reduced toxicity, as well as the potential for tumor down-staging and sphincter preservation, neoadjuvant approaches became the preferred method of administering chemotherapy and radiation. Furthermore, a subgroup of patients has been shown to present with complete clinical response to neoadjuvant therapy. This has resulted in the development of the non-operative "watch and wait" approach, which has initiated discussions on changing the interval from the completion of neoadjuvant therapy to surgical resection. The continued development of the multidisciplinary approach will only further improve our ability to provide patients with the best possible oncologic outcomes.

Nonoperative management of rectal cancer: identifying the ideal patients

Neoadjuvant chemoradiation (CRT) is considered one of the preferred treatment strategies for patients with locally advanced rectal cancer. This strategy may lead to significant tumor regression, ultimately leading to a complete pathologic response in up to 42% of patients. Assessment of tumor response following CRT and before radical surgery may identify patients with a complete clinical response who could possibly be managed nonoperatively with strict follow-up (watch-and-wait strategy). The present article deals with critical issues regarding appropriate selection of patients for this approach.

High-dose chemoradiotherapy and watchful waiting for distal rectal cancer: a prospective observational study

BACKGROUND

Abdominoperineal resection is the standard treatment for patients with distal T2 or T3 rectal cancers; however, the procedure is extensive and mutilating, and alternative treatment strategies are being investigated. We did a prospective observational trial to assess whether high-dose radiotherapy with concomitant chemotherapy followed by observation (watchful waiting) was successful for non-surgical management of low rectal cancer.

METHODS

Patients with primary, resectable, T2 or T3, N0-N1 adenocarcinoma in the lower 6 cm of the rectum were given chemoradiotherapy (60 Gy in 30 fractions to tumour, 50 Gy in 30 fractions to elective lymph node volumes, 5 Gy endorectal brachytherapy boost, and oral tegafur-uracil 300 mg/m(2)) every weekday for 6 weeks. Endoscopies and biopsies of the tumour were done at baseline, throughout the course of treatment (weeks 2, 4, and 6), and 6 weeks after the end of treatment. We allocated patients with complete clinical tumour regression, negative tumour site biopsies, and no nodal or distant metastases on CT and MRI 6 weeks after treatment to the observation group (watchful waiting). We referred all other patients to standard surgery. Patients under observation were followed up closely with endoscopies and selected-site biopsies, with surgical resection given for local recurrence. The primary endpoint was local tumour recurrence 1 year after allocation to the observation group. This study is registered with ClinicalTrials.gov, number NCT00952926. Enrolment is closed, but follow-up continues for secondary endpoints.

FINDINGS

Between Oct 20, 2009, and Dec 23, 2013, we enrolled 55 patients. Patients were recruited from three surgical units throughout Denmark and treated in one tertiary cancer centre (Vejle Hospital, Vejle, Denmark). Of 51 patients who were eligible, 40 had clinical complete response and were allocated to observation. Median follow-up for local recurrence in the observation group was 23·9 months (IQR 15·3-31·0). Local recurrence in the observation group at 1 year was 15·5% (95% CI 3·3-26·3). The most common acute grade 3 adverse event during treatment was diarrhoea, which affected four (8%) of 51 patients. Sphincter function in the observation group was excellent, with 18 (72%) of 25 patients at 1 year and 11 (69%) of 16 patients at 2 years reporting no faecal incontinence at all and a median Jorge-Wexner score of 0 (IQR 0-0) at all timepoints. The most common late toxicity was bleeding from the rectal mucosa; grade 3 bleeding was reported in two (7%) in 30 patients at 1 year and one (6%) of 17 patients at 2 years. There were no unexpected serious adverse reactions or treatment-related deaths.

INTERPRETATION

High-dose chemoradiotherapy and watchful waiting might be a safe alternative to abdominoperineal resection for patients with distal rectal cancer.

FUNDING

CIRRO-The Lundbeck Foundation Center for Interventional Research in Radiation Oncology and The Danish Council for Strategic Research.

Role of fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography in gastrointestinal cancers

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) has become a routine imaging modality for many malignancies and its use is currently increasing. In the present review article, we will summarize the evidence for FDG-PET/CT use in digestive cancers (excluding neuroendocrine tumours), and review the existing recommendations. While PET/CT is nowadays considered to be an important tool in the initial workup of oesophageal and anal cancers, new data are emerging regarding its use in assessing therapeutic efficacy, radiotherapy treatment planning, and detection of recurrence in case of isolated tumour marker elevation. Moreover, PET/CT may help decision making by detecting distant metastatic sites especially in potentially resectable metastatic colorectal cancer and, to a lesser extent, in localized gastric and pancreatic cancers. Finally, incidental focal colonic FDG uptakes require exploration by colonoscopy, as they are often associated with premalignant or malignant lesions.

Comprehensive evaluation of the effectiveness of gene expression signatures to predict complete response to neoadjuvant chemoradiotherapy and guide surgical intervention in rectal cancer

Neoadjuvant chemoradiotherapy (nCRT) may lead to complete tumor regression in rectal cancer patients. Prediction of complete response to nCRT may allow a personalized management of rectal cancer and spare patients from unnecessary radical total mesorectal excision with or without sphincter preservation. To identify a gene expression signature capable of predicting complete pathological response (pCR) to nCRT, we performed a gene expression analysis in 25 pretreatment biopsies from patients who underwent 5FU-based nCRT using RNA-Seq. A supervised learning algorithm was used to identify expression signatures capable of predicting pCR, and the predictive value of these signatures was validated using independent samples. We also evaluated the utility of previously published signatures in predicting complete response in our cohort. We identified 27 differentially expressed genes between patients with pCR and patients with incomplete responses to nCRT. Predictive gene signatures using subsets of these 27 differentially expressed genes peaked at 81.8% accuracy. However, signatures with the highest sensitivity showed poor specificity, and vice-versa, when applied in an independent set of patients. Testing previously published signatures on our cohort also showed poor predictive value. Our results indicate that currently available predictive signatures are highly dependent on the sample set from which they are derived, and their accuracy is not superior to current imaging and clinical parameters used to assess response to nCRT and guide surgical intervention.

Pitfalls of transanal endoscopic microsurgery for rectal cancer following neoadjuvant chemoradiation therapy

Transanal endoscopic microsurgery has become a very useful surgical tool for the management of selected cases of rectal cancer. However, the considerably high local recurrence rates led to the introduction of neoadjuvant therapies including radiation with or without chemotherapy. This treatment strategy may result in significant rates of tumor regression allowing the procedure to be offered to a significant proportion of cases. On the other hand, neoadjuvant chemoradiation (CRT) may also determine wound-healing difficulties with significant postoperative pain. In addition, salvage total mesorectal excision in the case of local recurrence may also be a challenging task. Finally, accurate selection criteria for this minimally invasive approach are still lacking and may be influenced by baseline staging, post-treatment staging and final pathology information. Ultimately, selection of patients for this treatment modality remains a significant challenge for the colorectal surgeon who should be aware of the pitfalls of this procedure in the setting of neoadjuvant CRT.

Prediction of response to preoperative chemoradiotherapy in patients with locally advanced rectal cancer

Preoperative chemoradiotherapy (CRT) combined with surgery has become a standard treatment strategy for patients with locally advanced rectal cancer (LARC). The pathological response is an important prognostic factor for LARC. The variety of tumor responses has increased the need to find a useful predictive model for the response to CRT to identify patients who will really benefit from this multimodal treatment. Magnetic resonance imaging (MRI), positron emission tomography-computed tomography (PET-CT), serum carcinoembryogenic antigen (CEA), molecular biomarkers analyzed by immunohistochemistry and gene expression profiling are the most used predictive models in LARC. The majority of predictors have yielded encouraging results, but there is still controversy. Diffusion-weighted MRI may be the best model to detect the dynamic changes of rectal cancer and predict the response at an early stage. Gene expression profiling and single nucleotide polymorphisms hold considerable promise to unveil the underlying complex genetics of response to CRT. Because each parameter has its own inherent shortcomings, combined models may be the future trend to predict the response.

Long-term outcome of local excision after preoperative chemoradiation for ypT0 rectal cancer

BACKGROUND

Local excision, as an alternative to radical resection for patients with pathological complete response (ypT0) after preoperative chemoradiation, is under investigation.

OBJECTIVE

The aim of the present study was to evaluate the long-term clinical outcome of a selected group of patients with ypT0 rectal cancer who underwent local excision with transanal endoscopic microsurgery as a definitive treatment.

PATIENTS

Between 1993 and 2013, 43 patients with rectal adenocarcinoma underwent complete full-thickness local excision with a transanal endoscopic microsurgery procedure after a regimen of chemoradiation. In all patients, rectal wall penetration was preoperatively assessed by endorectal ultrasound and/or magnetic resonance. Chemoradiation and transanal endoscopic microsurgery were indicated in patients refusing radical procedures or patients unfit for major abdominal procedures.

MAIN OUTCOME MEASURES

Patient characteristics, operative record, pathology report, and tumor recurrence were analyzed at a median follow-up of 81 months. The potential prognostic factors for recurrence, screened in univariate analysis, were analyzed by multivariate analysis by using the Cox regression model.

RESULTS

Thirteen patients (30.2%), without residual tumor in the surgical specimen (ypT0), were treated with transanal endoscopic microsurgery only. In this ypT0 group, 2 patients (15.4%) had postoperative complications: 1 bleeding and 1 suture dehiscence. Postoperative mortality was nil. No local and distal recurrences were observed, and no tumor-related mortality occurred. In 30 patients (69.8%), partial tumor chemoradiation response or the absence of tumor chemoradiation response was observed. In this group, recurrence occurred in 17 patients (56.7%).

LIMITATIONS

The study was limited by its retrospective nature, different protocols of chemoradiation and preoperative staging over time, and the small sample size.

CONCLUSIONS

Local excision with transanal endoscopic microsurgery can be considered a definitive therapeutic option in patients with rectal cancer treated with preoperative chemoradiation, when no residual tumor is found in the specimen. In this selected group, local excision offers excellent results in terms of survival and recurrence rates. In the presence of residual tumor, transanal endoscopic microsurgery should be considered as a large excisional biopsy (see Video, Supplemental Digital Content 1, http://links.lww.com/DCR/A157).

Is diffusion-weighted MRI superior to FDG-PET or FDG-PET/CT in evaluating and predicting pathological response to preoperative neoadjuvant therapy in patients with rectal cancer?

OBJECTIVE

This meta-analysis aimed to compare the diagnostic accuracy of diffusion-weighted magnetic resonance imaging (DW-MRI) and fluorodeoxyglucose-positron emission tomography (FDG-PET) or FDG-PET/computed tomography (CT) in evaluating and predicting pathological response to preoperative neoadjuvant chemoradiotherapy (NCRT) in patients with rectal cancer.

METHODS

A comprehensive literature research was conducted to identify the relevant studies for this meta-analysis. Combined sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated.

RESULTS

A total of 33 studies including 1564 patients met the inclusion criteria. The pooled sensitivity (81% [95% CI 74-86%] vs 85% [95% CI 75-91%]) and NPV (80% [95% CI 68-89%] vs 91% [95% CI 80-95%]) for FDG-PET or FDG-PET/CT were significantly lower than those for DW-MRI (P < 0.05). No differences were observed in pooled specificity and PPV between DW-MRI and FDG-PET or FDG-PET/CT. Further subgroup analyses showed that DW-MRI had higher sensitivity on adenocarcinomas alone than on those including mucinous-type adenocarcinomas (92% [95% CI 83-99%] vs 76% [95% CI 63-90%], P = 0.00).

CONCLUSIONS

DW-MRI is superior to FDG-PET or FDG-PET/CT in predicting and evaluating pathological responses to preoperative NCRT in patients with rectal cancer. However, its relatively low specificity and PPV limit its application in clinic, making it currently inappropriate to monitor such patients, especially those with mucinous-type rectal adenocarcinomas.

Multidisciplinary treatment of rectal cancer in 2014: Where are we going?

In the present review we discuss the recent developments and future directions in the multimodal treatment of locally advanced rectal cancer, with respect to staging and re-staging modalities, to the current role of neoadjuvant chemo-radiation and to the conservative and more limited surgical approaches based on tumour response after neoadjuvant combined therapy. When initial tumor staging is considered a high accuracy has been reported for T pre-treatment staging, while preoperative lymph node mapping is still suboptimal. With respect to tumour re-staging, all the current available modalities still present a limited accuracy, in particular in defining a complete response. The role of short vs long-course radiotherapy regimens as well as the optimal time of surgery are still unclear and under investigation by means of ongoing randomized trials. Observational management or local excision following tumour complete response are promising alternatives to total mesorectal excision, but need further evaluation, and their use outside of a clinical trial is not recommended. The preoperative selection of patients who will benefit from neoadjuvant radiotherapy or not, as well as the proper identification of a clinical complete tumour response after combined treatment modalities,will influence the future directions in the treatment of locally advanced rectal cancer.

Barium enema and CT volumetry for predicting pathologic response to preoperative chemoradiotherapy in rectal cancer patients

BACKGROUND

Preoperative chemoradiotherapy has been widely used for the prevention of local recurrence of locally advanced rectal cancer, and the effect of chemoradiotherapy is known to be associated with overall survival.

OBJECTIVE

We aimed to evaluate the association of the pathologic response grade with tumor recurrence rate after chemoradiotherapy, using radiographic analysis and the Response Evaluation Criteria in Solid Tumors as the parameters.

DESIGN

This study was conducted at a single tertiary care institution in Japan.

SETTING

This was a retrospective cohort study of patients undergoing preoperative chemoradiotherapy.

PATIENTS

A total of 101 low rectal cancer patients receiving preoperative chemoradiotherapy from July 2004 to August 2012 were enrolled.

MAIN OUTCOME MEASURES

The tumor reduction rate was measured with the use of traditional Response Evaluation Criteria in Solid Tumors, barium enema, and CT volumetry, and the correlation between the reduction rate and the pathologic response grade was examined.

RESULTS

The tumor reduction rate assessed according to Response Evaluation Criteria in Solid Tumors showed no association with the pathologic response grade (p =0.61). In contrast, the radiographic response rate by both barium enema and CT volumetry strongly correlated with the pathologic response grade (p < 0.0001 and p = 0.001).In terms of local tumor recurrence, those diagnosed as high responders by the pathologic response grade, Response Evaluation Criteria in Solid Tumors, barium enema, and CT volumetry had a lower recurrence rate (p =0.03, p =0.03, p =0.0002, and p =0.001). The difference between high responders and low responders was especially prominent by barium enema and CT volumetry.

LIMITATIONS

The study is limited by its retrospective nature.

CONCLUSIONS

Double-contrast barium enema and CT volumetry were superior to Response Evaluation Criteria in Solid Tumors in evaluating the effect of chemoradiotherapy and predicting the likelihood of tumor recurrence.

Multicenter Evaluation of Rectal cancer ReImaging pOst Neoadjuvant (MERRION) Therapy

OBJECTIVE

The aim of this study was to evaluate the utility of reimaging rectal cancer post-CRT (chemoradiotherapy) with magnetic resonance (MR) imaging of the pelvis for local staging and computed tomography of thorax, abdomen, and pelvis (CT TAP) to identify distant metastases.

BACKGROUND

The success of neoadjuvant CRT for locally advanced rectal cancer has changed an already complex management algorithm. There is no consensus whether patients should be restaged before surgery.

METHODS

Data from 5 institutions with prospectively maintained databases including patients who received neoadjuvant CRT for locally advanced rectal cancer were acquired. Only patients who had been staged pre- and post-CRT with MR imaging and CT TAP were included. MR findings were correlated with histopathological stage using weighted κ (kappa) statistics to test agreement, where a κ value of less than 0.5 was deemed unacceptable.

RESULTS

A total of 285 patients fulfilled the criteria for the study; 84% had American Joint Committee for Cancer stage 3 disease pre-CRT, and the remainder had stage 2 disease. Fourteen patients did not proceed to surgery post-CRT-2 were observed as "complete responders," and the remainder either had unresectable disease or were unfit for surgery. MR imaging could not predict T stage (κ = 0.212) or nodal involvement (κ = 0.336). Most pertinently, MR imaging was unable to detect a complete pathological response (κ = 0.021), nor could it discriminate T4 disease (κ = 0.445). CT TAP restaging altered management in 6.7% of patients, who had metastatic disease.

CONCLUSIONS

MR reimaging using standard protocols is of limited value in determining surgical approaches; a better modality of local restaging is required.

Local excision after preoperative chemoradiotherapy for rectal cancer: results of a multicenter phase II clinical trial

BACKGROUND

Transanal local excision has been suggested as an attractive approach for patients with rectal cancer who show a major clinical response after preoperative chemoradiotherapy.

OBJECTIVE

To evaluate the impact of transanal local excision on the local recurrence of rectal cancer in patients who had a major clinical response after preoperative chemoradiotherapy.

DESIGN

Sequential 2-stage phase II study for early efficacy.

SETTING

Multicenter study.

PATIENTS

Patients with clinical T3 or low-lying T2 rectal adenocarcinoma that showed a major clinical response after a preoperative chemoradiotherapy. Eligible patients underwent a full-thickness transanal local excision. According to their histopathology, the patients staged as ypT0-1 were observed, while the remaining patients were recommended to undergo a subsequent total mesorectal excision.

MAIN OUTCOME MEASURES

A local recurrence rate of ≤5% was set as a successful rate for stopping the trial early after the first stage.

RESULTS

The study group included 63 patients. Before chemoradiotherapy, patients were staged as clinical T3 (n = 42) and T2 (n = 21). After the local excision, 43 patients fulfilled the criteria to be observed with no further treatment. Nine of the remaining 20 patients for whom a subsequent total mesorectal excision was recommended refused surgery. Two of these patients who refused surgery had intraluminal local recurrence; both had a ypT2 tumor and underwent salvage surgery. The estimated cumulative 3-year overall survival, disease-free survival and local disease-free survival were 91.5% (95% CI: 75.9-97.2), 91.0% (95% CI: 77.0-96.6) and 96.9% (95% CI: 80.3-99.5), respectively.

LIMITATIONS

The time of follow-up is still short and the sample size is limited.

CONCLUSIONS

Our data suggest that local excision is a good option for patients with a major clinical response after chemoradiotherapy. A longer period of follow-up is required to confirm these findings.

Watch and wait approach following extended neoadjuvant chemoradiation for distal rectal cancer: are we getting closer to anal cancer management?

BACKGROUND

No immediate surgery (Watch and Wait) has been considered in select patients with complete clinical response after neoadjuvant chemoradiation to avoid postoperative morbidity and functional disorders after radical surgery.

OBJECTIVE

The purpose of this study was to demonstrate the long-term results of patients who had a complete clinical response following an alternative chemoradiation regimen and were managed nonoperatively.

DESIGN

This is a prospective study.

SETTINGS

This study was conducted at a single center.

PATIENTS

Seventy consecutive patients with T2-4N0-2M0 distal rectal cancer were studied. Neoadjuvant chemoradiotherapy included 54 Gy and 5-fluorouracil/leucovorin delivered in 6 cycles every 21 days. Patients were assessed for tumor response at 10 weeks from radiation completion. Patients with incomplete clinical response were referred to immediate surgery. Patients with complete clinical response were not immediately operated on and were monitored.

MAIN OUTCOME MEASURES

The primary outcomes measured were the initial complete clinical response rates after 10 weeks and the sustained complete clinical response rates after 12 months from chemoradiotherapy.

RESULTS

One patient died during chemoradiotherapy because of cardiac complications. Forty-seven (68%) patients had initial complete clinical response. Of these, 8 developed local regrowth within the first 12 months of follow-up (17%). Thirty-nine sustained complete clinical response at a median follow-up of 56 months (57%). An additional 4 patients (10%) developed late local recurrences (>12 months of follow-up). Overall, 35 patients never underwent surgery (50%).

LIMITATIONS

This study is limited by the short follow-up and small sample size.

CONCLUSION

Extended chemoradiation therapy with additional chemotherapy cycles and 54 Gy of radiation may result in over 50% of sustained (>12 months) complete clinical response rates that may ultimately avoid radical rectal resection. Local failures occur more frequently during the initial 12 months of follow-up in up to 17% of cases, whereas late recurrences are less common but still possible, leading to 50% of patients who never required surgery. Strict follow-up may allow salvage therapy in the majority of these patients (see Video, Supplemental Digital Content 1, http://links.lww.com/DCR/A113.).

How reliable is current imaging in restaging rectal cancer after neoadjuvant therapy?

In patients with advanced rectal cancer, neoadjuvant chemo radiotherapy provides tumor downstaging and downsizing and complete pathological response in up to 30% of cases. After proctectomy complete pathological response is associated with low rates of local recurrence and excellent long term survival. Several authors claim a less invasive surgery or a non operative policy in patients with partial or clinical complete response respectively, however to identify patients with true complete pathological response before surgical resection remains a challenge. Current imaging techniques have been reported to be highly accurate in the primary staging of rectal cancer, however neoadjuvant therapy course produces deep modifications on cancer tissue and on surrounding structures such as overgrowth fibrosis, deep stroma alteration, wall thickness, muscle disarrangement, tumor necrosis, calcification, and inflammatory infiltration. As a result, the same imaging techniques, when used for restaging, are far less accurate. Local tumor extent may be overestimated or underestimated. The diagnostic accuracy of clinical examination, rectal ultrasound, computed tomography, magnetic resonance imaging, and positron emission tomography using 18F-fluoro-2’-deoxy-D-glucose ranges between 25% and 75% being less than 60% in most studies, both for rectal wall invasion and for lymph nodes involvement. In particular the ability to predict complete pathological response, in order to tailor the surgical approach, remains low. Due to the radio-induced tissue modifications, combined with imaging technical aspects, low rate accuracy is achieved, making modern imaging techniques still unreliable in restaging rectal cancer after chemo-radiotherapy.

Neither FDG-PET Nor CT can distinguish between a pathological complete response and an incomplete response after neoadjuvant chemoradiation in locally advanced rectal cancer: a prospective study

OBJECTIVE

To prospectively compare the ability of flourodeoxyglucose-positron emission tomography (FDG-PET) and computed tomography (CT) to identify a pathological complete response (pCR) in patients with rectal cancer treated by chemoradiation.

BACKGROUND

A major obstacle in pursuing nonoperative management in patients with rectal cancer after chemoradiation is the inability to identify a pCR preoperatively.

METHODS

A total of 121 patients with rectal cancer were prospectively enrolled. FDG-PET scans and helical CT scans were obtained before and after neoadjuvant chemoradiation. Consensus readings of PET and CT scans were used to classify certainty of disease (5-point confidence rating scale). The ability of PET and CT scans to accurately distinguish a pCR (ypT0) from an incomplete response (ypT1-4) was estimated using the area under the receiver operating characteristic curve (AUC).

RESULTS

Of the 121 patients, 26 (21%) had a pCR. PET and CT scans were equally inadequate at distinguishing a pCR from an incomplete response (AUC = 0.64 for both, P = 0.97). Among the 26 patients with a pCR, 14 (54%) and 5 (19%) were classified as complete responders on PET and CT scans, respectively. Among the 95 patients with an incomplete pathological response, 63 (66%) and 90 (95%) were classified as incomplete responders on PET and CT scans, respectively. None of the individual PET parameters, including visual response score, mean standard uptake value (SUVmean), maximum SUV (SUVmax), and total lesion glycolysis, accurately distinguished a pCR (AUCs = 0.57-0.73).

CONCLUSIONS

Neither PET nor CT scans have adequate predictive value to be clinically useful in distinguishing a pCR from an incomplete response and, therefore, should not be obtained for the purpose of attempting to predict a pCR after neoadjuvant chemoradiation for rectal cancer.

Future directions in combined modality therapy for rectal cancer: reevaluating the role of total mesorectal excision after chemoradiotherapy

Most patients who develop rectal cancer present with locoregionally advanced (T3 or node-positive) disease. The standard management of locoregionally advanced rectal cancer is neoadjuvant concurrent chemoradiotherapy (nCRT), followed by radical resection (low-anterior resection or abdominoperineal resection with total mesorectal excision). Approximately 15% of patients can have a pathologic complete response (pCR) at the time of surgery, indicating that some patients can have no detectable residual disease after nCRT. The actual benefit of surgery in this group of patients is unclear. It is possible that omission of surgery in these patients, termed selective nonoperative management, can limit the toxicities associated with standard, multimodal combined modality therapy without compromising disease control. In this review, we discuss the clinical experiences to date using selective nonoperative management and various attempts at escalation of nCRT to improve the number of patients who have a pCR. We also explore several clinical, laboratory, imaging, histopathologic, and genetic biomarkers that have been tested as tools to predict which patients are most likely to have a pCR after nCRT.

Non-operative management for locally advanced rectal cancer: critical review and future perspective

SUMMARY Over the last few decades we have observed important advances in diagnostic imaging, surgery, pathology and multimodal treatments for rectal cancer, as well as increased efforts to reduce treatment-related toxicities and preserve quality of life for curatively treated patients. Neoadjuvant short-course radiotherapy and long-course chemoradiotherapy followed by total mesorectal excision remain widely accepted as the standard of care for patients with locally advanced rectal cancer. However, a carefully selected group of patients achieving a complete response to neoadjuvant chemoradiotherapy may be spared the effects of surgery and achieve satisfactory oncologic outcomes with a ‘wait-and-see’ strategy. Although supported by the results of previous studies, this intriguing paradigm shift needs prospective evaluation within a clinical trial setting and a more accurate prediction and assessment of response by means of tumor biomarkers and diagnostic imaging.

Clinical relevance of positron emission tomography/computed tomography-positive inguinal nodes in rectal cancer after neoadjuvant chemoradiation

AIM

Inguinal nodes may be a possible route for lymphatic spread in patients with distal rectal cancer. The outcome was examined for patients with distal rectal cancer undergoing neoadjuvant chemoradiation (CRT) and having 2-fluorine-18-fluoro-2-deoxy-d-glucose (FDG)-avid inguinal nodes using positron emission tomography/computed tomography (PET/CT) imaging.

METHOD

Ninety-nine consecutive patients with cT2-4N0-2M0 distal rectal adenocarcinoma were enrolled in a clinical trial (NCT00254683) and underwent baseline PET/CT followed by 54 Gy and 5-fluorouracil-based CRT. After CRT, patients underwent 6- and 12-week PET/CT. Patients with positive inguinal node uptake were compared with patients with negative uptake. The inguinal region was not included in the field of radiation therapy.

RESULTS

Seventeen (17%) patients had baseline positive inguinal node FDG uptake. They were more likely to have the tumour closer to the anal verge (2.0 vs 4.2 cm; P = 0.001). Of these, eight (47%) demonstrated a positive inguinal uptake at PET/CT after 12 weeks from CRT. Patients with inguinal node FDG uptake after CRT (positive PET at baseline and 12 weeks) had a significantly worse 3-year overall and disease-free survival (P = 0.02 and P = 0.03). After a median follow-up period of 22 months, none of these patients had developed inguinal recurrence.

CONCLUSION

Uptake of inguinal nodes at PET/CT may be present in up to 17% of patients with distal rectal cancer, particularly with ultra-low tumours. Nearly half of these nodes no longer show uptake after CRT despite the groin area not being included in the radiation field. Persistence of inguinal node uptake 12 weeks after CRT completion may be a marker for worse oncological outcome.

Application of FDG-PET/CT in Radiation Oncology

Positron emission tomography (PET)/computed tomography (CT), which combines the advantages of high sensitivity and specificity of PET and high resolution of CT, is a unique tool for cancer management. PET/CT has been widely used in cancer diagnosis and treatment. The article reviews the recent applications of PET/CT in radiation oncology, with a focus on ¹⁸F-fluorodeoxyglucose (FDG)-PET/CT, addressing the applications in treatment planning and treatment response assessment of radiation therapy.

Management of distal rectal cancer: results from a national survey

Owing to the complexity of distal rectal cancer its management requires a multidisciplinary approach. The diagnosis and the response after neoadjuvant chemoradiotherapy are not easy to assess and therefore the surgical approach is heterogeneous. The purpose of this survey is to evaluate the experiences of members of the Italian Society of Surgery in diagnosis and treatment strategies for rectal cancer and compare it with international practice. A questionnaire was devised comprising 18 questions with 11 sub-items making a total of 29 questions and submitted online to all the 2,500 members of the SIC starting from July 2010. The survey was completed in June 2011. The overall response rate was 17.8 % (444). The majority of the Italian surgeons' responses were in line with the international consensus reflecting the complex management of distal rectal cancer. Other opinions, especially those on staging, diverge from the common view of MRI being the gold standard in the assessment of loco-regional diffusion of the disease and on the superiority of FDG PET-CT versus CT for systemic staging. The timing for the re-staging and for surgery following neoadjuvant chemoradiotherapy does not reflect the international opinion. Italian surgeons are also exposed to the common difficulties encountered internationally in the management of distal rectal cancer. Probably, the implementation of an Italian rectal cancer registry and of many national and international multicentre studies may improve the management of rectal cancer in Italy.

Shifting concepts in rectal cancer management: a review of contemporary primary rectal cancer treatment strategies

The management of rectal cancer has transformed over the last 3 decades and continues to evolve. Some of these changes parallel progress made with other cancers: refinement of surgical technique to improve organ preservation, selective use of neoadjuvant (and adjuvant) therapy, and emergence of criteria suggesting a role for individually tailored therapy. Other changes are driven by fairly unique issues including functional considerations, rectal anatomic features, and surgical technical issues. Further complexity is due to the variety of staging modalities (each with its own limitations), neoadjuvant treatment alternatives, and competing strategies for sequencing multimodal treatment even for nonmetastatic disease. Importantly, observations of tumor response made in the era of neoadjuvant therapy are reshaping some traditionally held concepts about tumor behavior. Frameworks for prioritizing and integrating complex data can help to formulate treatment plans for patients.