Dose-Effect Relationship in Chemoradiotherapy for Locally Advanced Rectal Cancer: A Randomized Trial Comparing Two Radiation Doses

Tumor compactness improves the preoperative volumetry-based prediction of the pathological complete response of rectal cancer after preoperative concurrent chemoradiotherapy

In addition to clinical factors (tumor and node stage) and treatment factors (equivalent radiotherapy dose and chemotherapy regimen), we assessed whether different performances of various tumor volume measurements help predict the pathological complete response (pCR) of locally advanced rectal cancer (LARC) after preoperative concurrent chemoradiotherapy (CCRT). A total of 122 patients with LARC treated with a long course of CCRT, between December 2009 and March 2015, were enrolled in this bi-institutional study. Tumor delineation was based on standard T2-weighted magnetic resonance imaging or contrast-enhanced computed tomography before CCRT. Tumor compactness was defined as the ratio of the volume and the surface area. The tumor compactness-corrected TV (TCTV) was defined as the ratio of the real TV (RTV) and tumor compactness. Twenty-three (18.9%) patients had a pCR. Areas under the curve of the receiver operating characteristic for pCR prediction calculated using the RTV, cylindrical approximated TV (CATV), and TCTV were 0.724, 0.747, and 0.780, respectively. The prediction performance of TCTV was significantly more efficient than that of both RTV (P = 0.0057) and CATV (P = 0.0329). Multivariate logistic regression analysis revealed tumor compactness (P = 0.001), RTV (P = 0.042), and preoperative clinical nodal status (P = 0.044) as significant predictors of a pCR. In addition, poor tumor compactness was closely associated with lymphovascular space invasion (P = 0.008) and pathological nodal status (P = 0.003). For patients with LARC receiving preoperative CCRT, tumor compactness is a useful radiomic parameter for improving the volumetric based prediction model.

Definitive high-dose radiotherapy with concurrent chemotherapy for locally advanced rectal cancer: A case report and literature review

BACKGROUND

Standard management for locally advanced rectal cancer (LARC) involves preoperative chemoradiotherapy (CRT) and radical surgery. However, this level of treatment may be unnecessary for a subgroup of LARC patients. Previous reports have shown that approximately 20% of LARC patients experience a complete tumor response to preoperative CRT. Post-CRT nonoperative management of these patients may prevent morbidities associated with radical surgery. To our knowledge, this case report firstly presents the favorable long-term outcomes of a LARC patient who underwent definitive aim CRT.

METHODS

The patient was 73 years' old, and staging workups revealed T3N2bM0 rectal adenocarcinoma. He agreed to receive CRT, but refused surgery. A radiotherapy (RT) dose of 64.8 Gy was prescribed, which was higher than conventional (50.4 Gy) preoperative aim RT. The regimen of concurrent chemotherapy was the same as that used in preoperative aim CRT: 2 cycles of 5-fluorouracil and leucovorin.

RESULTS

Three months after CRT completion, a complete tumor response was identified clinically. Colonoscopic biopsy after 1 year showed no tumor cells. This patient is alive after 4 years with no evidence of recurrence or severe toxicity.

CONCLUSION

The long-term outcomes of this case indicate the feasibility of definitive high-dose RT with concurrent chemotherapy for LARC.

Clinicopathological outcomes of preoperative chemoradiotherapy using S-1 plus Irinotecan for T4 lower rectal cancer

PURPOSE

To investigate the clinicopathological outcomes of patients with T4 lower rectal cancer treated using preoperative chemoradiotherapy with S-1 plus Irinotecan.

METHODS

Between 2005 and 2011, 35 patients with T4M0 lower rectal cancer, diagnosed initially as T4a in 12 and as T4b in 23, were treated with 45 Gy of radiotherapy concomitantly with S-1 plus Irinotecan. The median follow-up period was 50.6 months (range 2-123 months).

RESULTS

A total of 32 patients (91.4 %) completed the radiotherapy and 26 (74.3 %) completed the full chemotherapy regimen. Radical surgery was then performed in 33 (94.3 %) of the 35 patients after the exclusion of two patients, who had macroscopic residual disease. The pathological diagnosis was downstaged from T4a to ypT0-3 in all 12 of those patients (100 %) and from T4b to ypT0-4a in 20 of those 23 patients (87.0 %). The tumor regression grade of 1a/1b/2/3 (complete response) was 10/8/15/2, respectively. In terms of long-term survival, the 5-year local relapse-free survival rate was 74.8 % and the recurrence-free survival rate was 52.0 %.

CONCLUSIONS

This regimen may result in favorable downstaging. Moreover, in this series, pathological evidence of involvement of adjacent organs was rare following preoperative chemoradiotherapy, in the patients with disease diagnosed as T4b at the initial staging.

Preoperative chemoradiation for locally advanced rectal cancer: comparison of three radiation dose and fractionation schedules

Purpose:

The standard radiation dose for patients with locally rectal cancer treated with preoperative chemoradiotherapy is 45–50 Gy in 25–28 fractions. We aimed to assess whether a difference exists within this dose fractionation range.

Materials and Methods:

A retrospective analysis was performed to compare three dose fractionation schedules. Patients received 50 Gy in 25 fractions (group A), 50.4 Gy in 28 fractions (group B), or 45 Gy in 25 fractions (group C) to the whole pelvis, as well as concurrent 5-fluorouracil. Radical resection was scheduled for 8 weeks after concurrent chemoradiotherapy.

Results:

Between September 2010 and August 2013, 175 patients were treated with preoperative chemoradiotherapy at our institution. Among those patients, 154 were eligible for analysis (55, 50, and 49 patients in groups A, B, and C, respectively). After the median follow-up period of 29 months (range, 5 to 48 months), no differences were found between the 3 groups regarding pathologic complete remission rate, tumor regression grade, treatment-related toxicity, 2-year locoregional recurrence-free survival, distant metastasis-free survival, disease-free survival, or overall survival. The circumferential resection margin width was a prognostic factor for 2-year locoregional recurrence-free survival, whereas ypN category was associated with distant metastasis-free survival, disease-free survival, and overall survival. High tumor regression grading score was correlated with 2-year distant metastasis-free survival and disease-free survival in univariate analysis.

Conclusion:

Three different radiation dose fractionation schedules, within the dose range recommended by the National Comprehensive Cancer Network, had no impact on pathologic tumor regression and early clinical outcome for locally advanced rectal cancer.

Increasing the Interval Between Neoadjuvant Chemoradiotherapy and Surgery in Rectal Cancer: A Meta-analysis of Published Studies

OBJECTIVE

The aim of this meta-analysis was to demonstrate whether a longer interval between the end of neoadjuvant chemoradiotherapy (CRT) and surgery is associated with a better rate of pathological complete response (pCR) in rectal cancer.

BACKGROUND

The standard of care in locally advanced rectal cancer is preoperative, long course (5-fluorouracil-based) CRT. After this neoadjuvant CRT, surgical exploration is undertaken 6 to 8 weeks later.

METHODS

PubMed, EMBASE, the ISI Web of Science, and The Cochrane Library (CENTRAL) were searched systematically for prospective or retrospective studies reporting oncological results for intervals longer or shorter than 6 to 8 weeks between the end of CRT and surgery, in rectal cancer. The primary endpoint, reported as relative risk (RR), was the rate of pCR. Secondary endpoints were overall survival (OS), disease-free survival (DFS), R0 resection rates, sphincter preservations, and wound/anastomotic complications. A meta-analysis was performed, using the fixed- or random-effects model, with Review Manager 5.1.

RESULTS

Thirteen trials, including 3584 patients, were identified, and overall, an interval longer than 6 to 8 weeks from the end of neoadjuvant CRT and surgery significantly improved the pCR (RR = 1.42, 95% confidence interval: 1.19-1.68; P < 0.0001). Pathological complete responses increased from 13.7% to 19.5% in the longer interval group, and the OS, DFS, R0 resection rates, sphincter preservation, and complication rates were similar in the 2 groups.

CONCLUSIONS

A longer waiting interval (more than the classical 6-8 weeks) from the end of preoperative CRT increases the rate of pCR by 6% in rectal cancer, with similar outcomes and complication rates. These results should be validated prospectively in a randomized trial.

Drug Combinations in Preoperative Chemoradiation for Rectal Cancer

Preoperative radiotherapy has an accepted role in reducing the risk of local recurrence in locally advanced resectable rectal cancer, particularly when the circumferential resection margin is breached or threatened, according to magnetic resonance imaging. Fluoropyrimidine-based chemoradiation can obtain a significant down-sizing response and a curative resection can then be achieved. Approximately, 20% of the patients can also obtain a pathological complete response, which is associated with less local recurrences and increased survival. Patients who achieve a sustained complete clinical response may also avoid radical surgery. In unresectable or borderline resectable tumors, around 20% of the patients still fail to achieve a sufficient down-staging response with the current chemoradiation schedules. Hence, investigators have aspired to increase pathological complete response rates, aiming to improve curative resection rates, enhance survival, and potentially avoid mutilating surgery. However, adding additional cytotoxic or biological agents have not produced dramatic improvements in outcome and often led to excess surgical morbidity and higher levels of acute toxicity, which effects on compliance and in the global efficacy of chemoradiation.

Sequential boost in neoadjuvant irradiation for T3N0-1 rectal cancer: long-term results from a single-center experience

PURPOSE

To evaluate the influence of radiation dose on tumor regression grade (TRG) and sphincter preservation rate in a series of cT3N0-1 rectal cancer patients treated with neoadjuvant chemoradiotherapy (CT-RT) with or without a sequential radiation boost.

MATERIALS AND METHODS

Between May 2002 and September 2013, 116 cases were eligible for retrospective evaluation. Radiotherapy was delivered for a total dose of 45 Gy (no boost arm) or 50.4 Gy (boost arm). TRG was evaluated with the Dworak scale.

RESULTS

Median follow-up was 62 months (range, 12-138 months). The 5-year overall survival and local control rates were 72% and 93%, respectively. Fifty-five patients (47%) were treated with a sequential radiation boost and 61 (53%) without a boost. Eighty patients (72%) presented T3N0 disease and 32 (28%) T3N1 disease. Concomitant capecitabine was administered in 92 cases (79%) and intravenous 5-fluorouracil in 24 cases (21%). Sphincter preservation was performed in 82% of patients in the boost arm and 66% in the no-boost arm. A higher TRG was related to a longer interval between neoadjuvant treatment and surgery (p&lt;0.001). The probability of a TRG ≥2 was 2.5 times higher in the boost arm. A gain in local control, estimated at 4% during the first 3 years after CT-RT, favored the boost arm.

CONCLUSIONS

The long-term results from our single-center experience confirm literature data on the role of a sequential boost in tumor response after neoadjuvant CT-RT in a series of cT3N0-1 rectal cancer patients.

Efficacy and Safety of Low-Dose-Rate Endorectal Brachytherapy as a Boost to Neoadjuvant Chemoradiation in the Treatment of Locally Advanced Distal Rectal Cancer: A Phase-II Clinical Trial

PURPOSE

Despite advances in rectal cancer treatment over the last decade, local control and risk of late side effects due to external beam radiation therapy (EBRT) remain as concerns. The present study aimed to investigate the efficacy and the safety of low-dose-rate endorectal brachytherapy (LDRBT) as a boost to neoadjuvant chemoradiation for use in treating locally advanced distal rectal adenocarcinomas.

METHODS

This phase-II clinical trial included 34 patients (as the study arm) with newly diagnosed, locally advanced (clinical T3-T4 and/or N1/N2, M0) lower rectal cancer. For comparative analysis, 102 matched patients (as the historical control arm) with rectal cancer were also selected. All the patients were treated with LDRBT (15 Gy in 3 fractions) and concurrent chemoradiation (45-50.4 Gy). Concurrent chemotherapy consisted of oxaliplatin 130 mg/m(2) intravenously on day 1 plus oral capecitabine 825 mg/m(2) twice daily during LDRBT and EBRT.

RESULTS

The study results revealed a significant differences between the study arm and the control arm in terms in the pathologic tumor size (2.1 cm vs. 3.6 cm, P = 0.001), the pathologic tumor stage (35% T3-4 vs. 65% T3-4, P = 0.003), and the pathologic complete response (29.4% vs. 11.7%, P < 0.028). Moreover, a significantly higher dose of EBRT (P = 0.041) was found in the control arm, and a longer time to surgery was observed in the study arm (P < 0.001). The higher rate of treatment-related toxicities, such as mild proctitis and anemia, in the study arm was tolerable and easily manageable.

CONCLUSION

A boost of LDRBT can optimize the pathologic complete response, with acceptable toxicities, in patients with distal rectal cancer.

Functional Radiotherapy Targeting using Focused Dose Escalation

Various quantitative and semi-quantitative imaging biomarkers have been identified that may serve as valid surrogates for the risk of recurrence after radiotherapy. Tumour characteristics, such as hypoxia, vascularity, cellular proliferation and clonogen density, can be geographically mapped using biological imaging techniques. The potential gains in therapeutic ratio from the precision targeting of areas of intrinsic resistance makes focused dose escalation an exciting field of study. This overview will explore the issues surrounding biologically optimised radiotherapy, including its requirements, feasibility, technical considerations and potential applicability.

MRI volumetry for prediction of tumour response to neoadjuvant chemotherapy followed by chemoradiotherapy in locally advanced rectal cancer

OBJECTIVE

To investigate if MRI-assessed tumour volumetry correlates with histological tumour response to neoadjuvant chemotherapy (NACT) and subsequent chemoradiotherapy (CRT) in locally advanced rectal cancer (LARC).

METHODS

Data from 69 prospectively enrolled patients with LARC receiving NACT followed by CRT and radical surgery were analysed. Whole-tumour volumes were contoured in T2 weighted MR images obtained pre-treatment (VPRE), after NACT (VNACT) and after the full course of NACT followed by CRT (VCRT). VPRE, VNACT and tumour volume changes relative to VPRE, ΔVNACT and ΔVCRT were calculated and correlated to histological tumour regression grade (TRG).

RESULTS

61% of good histological responders (TRG 1-2) to NACT followed by CRT were correctly predicted by combining VPRE < 10.5 cm(3), ΔVNACT > -78.2% and VNACT < 3.3 cm(3). The highest accuracy was found for VNACT, with 55.1% sensitivity given 100% specificity. The volume regression after completed NACT and CRT (VCRT) was not significantly different between good and poor responders (TRG 1-2 vs TRG 3-5).

CONCLUSION

MRI-assessed small tumour volumes after NACT correlated with good histological tumour response (TRG 1-2) to the completed course of NACT and CRT. Furthermore, by combining tumour volume measurements before, during and after NACT, more good responders were identified.

ADVANCES IN KNOWLEDGE

MRI volumetry may be a tool for early identification of good and poor responders to NACT followed by CRT and surgery in LARC in order to aid more individualized, multimodal treatment.

How can we determine the best neoadjuvant chemoradiotherapy regimen for rectal cancer?

SUMMARY 

The current management of patients with clinically defined ‘locally advanced rectal cancer’ often involves fluoropyrimidine-based preoperative chemoradiotherapy (CRT) followed by total mesorectal excision. The focus remains primarily on reducing local recurrence, and improving survival, with organ preservation an increasing target. The best neoadjuvant CRT is the most effective regimen, balanced against the tolerability and late functional consequences, which should be selected for the individual according to their individual risk of local and distant recurrence. Hence, what makes the best neoadjuvant treatment depends on the activity and toxicity of the particular schedule, the aims of treatment, the individual disease characteristics and the individual patient pharmacogenomics. Current research efforts focus on enhancing the efficacy of CRT by integrating additional cytotoxics and biologically targeted agents.

Dose-response of acute urinary toxicity of long-course preoperative chemoradiotherapy for rectal cancer

BACKGROUND

Long-course preoperative chemoradiotherapy (chemo-RT) improves outcomes for rectal cancer patients, but acute side effects during treatment may cause considerable patient discomfort and may compromise treatment compliance. We developed a dose-response model for acute urinary toxicity based on a large, single-institution series.

MATERIAL AND METHODS

In total 345 patients were treated with (chemo-)RT for primary rectal cancer from January 2007 to May 2012. Urinary toxicity during RT was scored prospectively using the CTCAE v 3.0 cystitis score (grade 0-5). Clinical variables and radiation dose to the bladder were related to graded toxicity using multivariate ordinal logistic regression. Three models were optimized, each containing all available clinical variables and one of three dose metrics: Mean dose (Dmean), equivalent uniform dose (EUD), or relative volume given x Gy or above (dose cut-off model, Vx). The optimal dose metric was chosen using the Akaike Information Criterion (AIC).

RESULTS

Grade 1 cystitis was experienced by 138 (40%), grade 2 by 39 (11%) and grade 3 by two (1%) patients, respectively. Dose metrics were significantly correlated with toxicity in all models, but the dose cut-off model provided the best AIC value. The only significant clinical risk factors in the Vx model were male gender (p = 0.006) and brachytherapy boost (p = 0.02). Reducing the model to include gender, brachytherapy boost and Vx yielded odds ratios ORmale = 1.82 (1.17-2.80), ORbrachy = 1.36 (1.02-1.80 for each 5 Gy), x = 35.1 Gy (28.6-41.5 Gy). The predicted risk of grade 2 and above cystitis ranged from 2% to 26%.

CONCLUSION

Acute cystitis correlated significantly with radiation dose to the bladder; the dose-cut-off model (V35Gy) was superior to Dmean and EUD models. Male gender and brachytherapy boost increased the risk of toxicity. Wide variation in predicted risks suggests room for treatment optimization using individual dose constraints.

Organ preservation in rectal cancer: have all questions been answered?

Improved treatment strategies have eliminated local control as the major problem in rectal cancer. With increasing awareness of long-term toxic effects in survivors of rectal cancer, organ-preservation strategies are becoming more popular. After chemoradiotherapy, both watchful waiting and local excision are used as possible alternatives for radical surgery. Although these seem attractive strategies, many issues about the safety of organ preservation remain. Additionally, radiotherapy strategies are mainly aimed at intermediate and high-risk rectal tumours, and adaptation of this standard practice for a completely new treatment indication has yet to start. This Review will discuss the options and problems of organ preservation, and address the research questions that need to be answered in the coming years, with a specific focus on radiotherapy.

Neoadjuvant radiotherapy in rectal cancer

SUMMARY 

In the treatment of rectal cancer, neoadjuvant (chemo)radiotherapy is used to decrease the locoregional recurrence risk. The most common treatment consists of neoadjuvant radiotherapy to a dose of 45–50 Gy, combined with 5-fluorouracil or capecitabine-based chemotherapy. In parts of Europe, a short-course radiotherapy schedule of 5 × 5 Gy in 1 week is practiced for patients in whom no downstaging is required to achieve a radical resection. With the increased interest in organ preserving strategies, indications for chemoradiotherapy are changing and the focus has changed from achieving radical resections toward maximal downstaging. In this review, indications for and types of neoadjuvant treatment in rectal cancer are discussed, as well as new aspects related to organ preservation.

Impact of radiotherapy boost on pathological complete response in patients with locally advanced rectal cancer: a systematic review and meta-analysis

PURPOSE

We conducted a systematic review and meta-analysis to quantify the pathological complete response (pCR) rate after preoperative (chemo)radiation with doses of ⩾60Gy in patients with locally advanced rectal cancer. Complete response is relevant since this could select a proportion of patients for which organ-preserving strategies might be possible. Furthermore, we investigated correlations between EQD2 dose and pCR-rate, toxicity or resectability, and additionally between pCR-rate and chemotherapy, boost-approach or surgical-interval.

METHODS AND MATERIALS

PubMed, EMBASE and Cochrane libraries were searched with the terms 'radiotherapy', 'boost' and 'rectal cancer' and synonym terms. Studies delivering a preoperative dose of ⩾60 Gy were eligible for inclusion. Original English full texts that allowed intention-to-treat pCR-rate calculation were included. Study variables, including pCR, acute grade ⩾3 toxicity and resectability-rate, were extracted by two authors independently. Eligibility for meta-analysis was assessed by critical appraisal. Heterogeneity and pooled estimates were calculated for all three outcomes. Pearson correlation coefficients were calculated between the variables mentioned earlier.

RESULTS

The search identified 3377 original articles, of which 18 met our inclusion criteria (1106 patients). Fourteen studies were included for meta-analysis (487 patients treated with ⩾60 Gy). pCR-rate ranged between 0.0% and 44.4%. Toxicity ranged between 1.3% and 43.8% and resectability-rate between 34.0% and 100%. Pooled pCR-rate was 20.4% (95% CI 16.8-24.5%), with low heterogeneity (I2 0.0%, 95% CI 0.00-84.0%). Pooled acute grade ⩾3 toxicity was 10.3% (95% CI 5.4-18.6%) and pooled resectability-rate was 89.5% (95% CI 78.2-95.3%).

CONCLUSION

Dose escalation above 60 Gy for locally advanced rectal cancer results in high pCR-rates and acceptable early toxicity. This observation needs to be further investigated within larger randomized controlled phase 3 trials in the future.

MR imaging for rectal cancer: the role in staging the primary and response to neoadjuvant therapy

Pre-operative staging is an essential aspect of modern rectal cancer management and radiological assessment is central to this process. An ideal radiological assessment should provide sufficient information to reliably guide pre-operative decision-making. Technical advances allow high-resolution imaging to not only provide prognostic information but to define the anatomy, helping the surgeon to anticipate potential pitfalls during the operation. The main imaging modality for local staging of rectal cancer is Magnetic Resonance Imaging (MRI), as it defines the tumour and relevant anatomy providing the most detail on the important prognostic factors that influence treatment choice. In addition, there is an emerging role for MRI in the assessment of the response to neoadjuvant therapy. This article is an evidence-based review of rectal cancer staging focusing on post-treatment assessment of response using MRI. The discussion extends into the implications for reliably assessing response and how this may influence future rectal cancer management.

Long-term results of a randomized trial in locally advanced rectal cancer: no benefit from adding a brachytherapy boost

PURPOSE/OBJECTIVE(S)

Mature data on tumor control and survival are presented from a randomized trial of the addition of a brachytherapy boost to long-course neoadjuvant chemoradiation therapy (CRT) for locally advanced rectal cancer.

METHODS AND MATERIALS

Between March 2005 and November 2008, 248 patients with T3-4N0-2M0 rectal cancer were prospectively randomized to either long-course preoperative CRT (50.4 Gy in 28 fractions, per oral tegafur-uracil and L-leucovorin) alone or the same CRT schedule plus a brachytherapy boost (10 Gy in 2 fractions). The primary trial endpoint was pathologic complete response (pCR) at the time of surgery; secondary endpoints included overall survival (OS), progression-free survival (PFS), and freedom from locoregional failure.

RESULTS

Results for the primary endpoint have previously been reported. This analysis presents survival data for the 224 patients in the Danish part of the trial. In all, 221 patients (111 control arm, 110 brachytherapy boost arm) had data available for analysis, with a median follow-up time of 5.4 years. Despite a significant increase in tumor response at the time of surgery, no differences in 5-year OS (70.6% vs 63.6%, hazard ratio [HR] = 1.24, P=.34) and PFS (63.9% vs 52.0%, HR=1.22, P=.32) were observed. Freedom from locoregional failure at 5 years were 93.9% and 85.7% (HR=2.60, P=.06) in the standard and in the brachytherapy arms, respectively. There was no difference in the prevalence of stoma. Explorative analysis based on stratification for tumor regression grade and resection margin status indicated the presence of response migration.

CONCLUSIONS

Despite increased pathologic tumor regression at the time of surgery, we observed no benefit on late outcome. Improved tumor regression does not necessarily lead to a relevant clinical benefit when the neoadjuvant treatment is followed by high-quality surgery.

Optimal Time Intervals between Pre-Operative Radiotherapy or Chemoradiotherapy and Surgery in Rectal Cancer?

BACKGROUND

In rectal cancer therapy, radiotherapy or chemoradiotherapy (RT/CRT) is extensively used pre-operatively to (i) decrease local recurrence risks, (ii) allow radical surgery in non-resectable tumors, and (iii) increase the chances of sphincter-saving surgery or (iv) organ-preservation. There is a growing interest among clinicians and scientists to prolong the interval from the RT/CRT to surgery to achieve maximal tumor regression and to diminish complications during surgery.

METHODS

The pros and cons of delaying surgery depending upon the aim of the pre-operative RT/CRT are critically evaluated.

RESULTS

Depending upon the clinical situation, the need for a time interval prior to surgery to allow tumor regression varies. In the first and most common situation (i), no regression is needed and any delay beyond what is needed for the acute radiation reaction in surrounding tissues to wash out can potentially only be deleterious. After short-course RT (5Gyx5) with immediate surgery, the ideal time between the last radiation fraction is 2-5 days, since a slightly longer interval appears to increase surgical complications. A delay beyond 4 weeks appears safe; it results in tumor regression including pathologic complete responses, but is not yet fully evaluated concerning oncologic outcome. Surgical complications do not appear to be influenced by the CRT-surgery interval within reasonable limits (about 4-12 weeks), but this has not been sufficiently explored. Maximum tumor regression may not be seen in rectal adenocarcinomas until after several months; thus, a longer than usual delay may be of benefit in well responding tumors if limited or no surgery is planned, as in (iii) or (iv), otherwise not.

CONCLUSION

A longer time interval after CRT is undoubtedly of benefit in some clinical situations but may be counterproductive in most situations. After short-course RT, long-term results from the clinical trials are not yet available to routinely recommend an interval longer than 2-5 days, unless the tumor is non-resectable at diagnosis.

Aims of combined modality therapy in rectal cancer (M0)

OPTIMIZING THE COST/BENEFIT RATIO OF TREATMENT: Evidence Based The aim of a cancer treatment is always to achieve the maximum of cure rate with a minimum of toxicity and best quality of life at an acceptable cost for the society. It is always a multifactorial challenge depending on the patient, the tumor, the doctor, and the society cultural and financial backgrounds. The goal is to find the best cost/benefit ratio between all possible strategies in agreement with a well-informed patient. In rectal cancer (M0) surgery is the cornerstone of treatment. Combined modality therapies aim at optimizing the cost/benefit ratio of possible strategies and only randomized trials can bring strong evidence regarding their results and recommendations. LESSONS FROM RANDOMIZED TRIALS: quite modest During the past decades many phase III trials have shown that: (1) neoadjuvant treatment even with "TME" surgery was better than adjuvant, (2) chemoradiotherapy (CRT) was better than RT alone, (3) long course CRT was probably more efficient (in terms of ypCR) than short course (25/5), and (4) capecitabine was as efficient as 5 FU but oxaliplatin was not adding benefit. Overall, the gains of nCRT remain modest and it is mainly a reduction in local relapse not exceeding 5 %, but no benefit in survival and neither in sphincter saving surgery has been proven. The way forwards organ preservation in case of CCR. Local control: can probably be improved for T4 tumors by RT dose escalation. Survival: can be increased by innovative medical treatment either before or after surgery.

TOXICITY

may be reduced by a less aggressive treatment in elderly. Conservative treatment: A new field of clinical research is to achieve "organ preservation" (and not only sphincter saving). To modify the surgical approach and preserve the whole rectum, neoadjuvant treatment must achieve safely a clinical complete response. As rectal adenocarcinoma is a relatively radioresistant tumor endocavitary irradiation (contact X-Ray) is a promising safe approach and this hypothesis will be addressed by the OPERA randomized trial.

Neo-adjuvant radiotherapy in rectal cancer

In rectal cancer treatment, attention has focused on the local primary tumour and the regional tumour cell deposits to diminish the risk of a loco-regional recurrence. Several large randomized trials have also shown that combinations of surgery, radiotherapy and chemotherapy have markedly reduced the risk of a loco-regional recurrence, but this has not yet had any major influence on overall survival. The best results have been achieved when the radiotherapy has been given preoperatively. Preoperative radiotherapy improves loco-regional control even when surgery has been optimized to improve lateral clearance, i.e., when a total mesorectal excision has been performed. The relative reduction is then 50%-70%. The value of radiotherapy has not been tested in combination with more extensive surgery including lateral lymph node clearance, as practised in some Asian countries. Many details about how the radiotherapy is performed are still open for discussion, and practice varies between countries. A highly fractionated radiation schedule (5 Gy × 5), proven efficacious in many trials, has gained much popularity in some countries, whereas a conventionally fractionated regimen (1.8-2.0 Gy × 25-28), often combined with chemotherapy, is used in other countries. The additional therapy adds morbidity to the morbidity that surgery causes, and should therefore be administered only when the risk of loco-regional recurrence is sufficiently high. The best integration of the weakest modality, to date the drugs (conventional cytotoxics and biologicals) is not known. A new generation of trials exploring the best sequence of treatments is required. Furthermore, there is a great need to develop predictors of response, so that treatment can be further individualized and not solely based upon clinical factors and anatomic imaging.

EURECCA consensus conference highlights about rectal cancer clinical management: the radiation oncologist's expert review

BACKGROUND AND PURPOSE

Although rectal and colon cancer management has progressed greatly in the last few decades clinical outcomes still need to be optimized. Furthermore, consensus is required on several issues as some of the main international guidelines provide different recommendations. The European Registration of Cancer Care (EURECCA) drew up documents to standardize management and care in Europe and aid in decision-making.

MATERIAL AND METHODS

In the present section the panel of experts reviews and discusses data from the literature on rectal cancer, focusing on recommendations for selecting between short-course radiotherapy (SCRT) and long-course radio-chemotherapy (LCRTCT) as preoperative treatment as well as on the controversies about adjuvant treatment in patients who had received a pre-operative treatment.

RESULTS

The starting-point of the present EURECCA document is that adding SCRT or LCRTCT to TME improved loco-regional control but did not increase overall survival in any single trial which, in any case, had improved with the introduction of total mesorectal excision (TME) into clinical practice. Moderate consensus was achieved for cT3 anyNM0 disease. In this frame, agreement was reached on either SCRT followed by immediate surgery or LCRTCT with delayed surgery for mesorectal fascia (MRF) negative tumors at presentation. LCRTCT was recommended for tumor shrinkage in MRF+ at presentations but if patients were not candidates for chemotherapy, SCRT with delayed surgery is an option/alternative. LCRTCT was recommended for cT4 anycNM0. SCRT offers the advantages of less acute toxicity and lower costs, and LCRTCT tumor shrinkage and down-staging, with 13-36% pathological complete response (pCR) rates. To improve the efficacy of preoperative treatment both SCRT and LCRTCT have been, or are being, associated with diverse schedules of chemotherapy and even new targeted therapies but without any definitive evidence of benefit. Nowadays, standard treatment is fluoropyrimidine alone since alternative agents and regimens have not been shown to be more active, only more toxic.

CONCLUSIONS

The EURECCA panel summarized available evidence in an attempt to reduce variance in rectal cancer management. This is expected to benefit patients. Results from ongoing randomized trials will help clarify some of the issues that are still under debate.

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.

Ultrasound elastography in patients with rectal cancer treated with chemoradiation

OBJECTIVE

The current literature has described several predictive markers in rectal cancer patients treated with chemoradiation, but so far none of them have been validated for clinical use. The purpose of the present study was to compare quantitative elastography based on ultrasound measurements in the course of chemoradiation with tumor response based on T stage classification and the Mandard tumor regression grading (TRG).

MATERIALS AND METHODS

We prospectively examined 31 patients with rectal cancer planned for high dose radiochemotherapy. The tumor and the mesorectal fat elasticity were measured using the Acoustic Radiation Force Impulse to generate information on the mechanical properties of the tissue. The objective quantitative elastography shear wave velocity was compared to the T stage classification and TRG.

RESULTS

The baseline mean tumor elasticity was 3.13 m/s. Two and six weeks after the start of chemoradiation the velocities were 2.17 m/s and 2.11 m/s, respectively. The difference between baseline velocity and velocities during the treatment course was statistically significant, (p<0.0001). Patients with tumor confined to the rectal wall at histopathology (ypT1-2) had a mean elasticity measurement after two weeks of treatment of 1.95 m/s, whereas tumors invading the mesorectal fat (ypT3-4) had a velocity of 2.47 m/s, (p<0.05). The mean elasticity tended to be lower (1.99m/s) after two weeks in patients with TRG 1-2 responses in contrast to 2.24 m/s in those with TRG 3-4.

CONCLUSION

Ultrasound elastography after two weeks of chemoradiation seems to hold early predictive information to the pathological T stage.

Transrectal ultrasound and magnetic resonance imaging measurement of extramural tumor spread in rectal cancer

AIM: To evaluate the agreement between transrectal ultrasound (TRUS) and magnetic resonance imaging (MRI) in classification of ≥ T3 rectal tumors.

METHODS: From January 2010 to January 2012, 86 consecutive patients with ≥ T3 tumors were included in this study. The mean age of the patients was 66.4 years (range: 26-91 years). The tumors were all ≥ T3 on TRUS. The sub-classification was defined by the penetration of the rectal wall: a: 0 to 1 mm; b: 1-5 mm; c: 6-15; d: > 15 mm. Early tumors as ab (≤ 5 mm) and advanced tumors as cd (> 5 mm). All patients underwent TRUS using a 6.5 MHz transrectal transducer. The MRI was performed with a 1.5 T Philips unit. The TRUS findings were blinded to the radiologist performing the interpretation of the MRI images and measuring the depth of extramural tumor spread.

RESULTS: TRUS found 51 patients to have an early ≥ T3 tumors and 35 to have an advanced tumor, whereas MRI categorized 48 as early ≥ T3 tumors and 38 as advanced tumors. No patients with tumors classified as advanced by TRUS were found to be early on MRI. The kappa value in classifying early versus advanced T3 rectal tumors was 0.93 (95% CI: 0.85-1.00). We found a kappa value of 0.74 (95% CI: 0.63-0.86) for the total sub-classification between the two methods. The mean maximal tumor outgrowth measured by TRUS, 5.5 mm ± 5.63 mm and on MRI, 6.3 mm ± 6.18 mm, P = 0.004. In 19 of the 86 patients the following CT scan or surgery revealed distant metastases; of the 51 patients in the ultrasound ab group three (5.9%) had metastases, whereas 16 (45.7%) of 35 in the cd group harbored distant metastases, P = 0.00002. The odds ratio of having distant metastases in the ultrasound cd group compared to the ab group was 13.5 (95% CI: 3.5-51.6), P = 0.00002. The mean maximal ultrasound measured outgrowth was 4.3 mm (95% CI: 3.2-5.5 mm) in patients without distant metastases, while the mean maximal outgrowth was 9.5 mm (95% CI: 6.2-12.8 mm) in the patients with metastases, P = 0.00004. Using the MRI classification three (6.3%) of 48 in the MRI ab group had distant metastases, while 16 (42.1%) of the 38 in the MRI cd group, P = 0.00004. The MRI odds ratio was 10.9 (95% CI: 2.9-41.4), P = 0.00008. The mean maximal MRI measured outgrowth was 4.9 mm (95% CI: 3.7-6.1 mm) in patients without distant metastases, while the mean maximal outgrowth was 11.5 mm (95% CI: 7.8-15.2 mm) in the patients with metastases, P = 0.000006.

CONCLUSION: There is good agreement between TRUS and MRI in the pretreatment sub-classification of ≥ T3 tumors. Distant metastases are more frequent in the advanced group.

Radiation dose-response model for locally advanced rectal cancer after preoperative chemoradiation therapy

PURPOSE

Preoperative chemoradiation therapy (CRT) is part of the standard treatment of locally advanced rectal cancers. Tumor regression at the time of operation is desirable, but not much is known about the relationship between radiation dose and tumor regression. In the present study we estimated radiation dose-response curves for various grades of tumor regression after preoperative CRT.

METHODS AND MATERIALS

A total of 222 patients, treated with consistent chemotherapy and radiation therapy techniques, were considered for the analysis. Radiation therapy consisted of a combination of external-beam radiation therapy and brachytherapy. Response at the time of operation was evaluated from the histopathologic specimen and graded on a 5-point scale (TRG1-5). The probability of achieving complete, major, and partial response was analyzed by ordinal logistic regression, and the effect of including clinical parameters in the model was examined. The radiation dose-response relationship for a specific grade of histopathologic tumor regression was parameterized in terms of the dose required for 50% response, D50,i, and the normalized dose-response gradient, γ50,i.

RESULTS

A highly significant dose-response relationship was found (P=.002). For complete response (TRG1), the dose-response parameters were D50,TRG1=92.0 Gy (95% confidence interval [CI] 79.3-144.9 Gy), γ50,TRG1=0.982 (CI 0.533-1.429), and for major response (TRG1-2) D50,TRG1&2=72.1 Gy (CI 65.3-94.0 Gy), γ50,TRG1&2=0.770 (CI 0.338-1.201). Tumor size and N category both had a significant effect on the dose-response relationships.

CONCLUSIONS

This study demonstrated a significant dose-response relationship for tumor regression after preoperative CRT for locally advanced rectal cancer for tumor dose levels in the range of 50.4-70 Gy, which is higher than the dose range usually considered.