Neoadjuvant chemoradiation for distal rectal cancer: 5-year updated results of a randomized phase 2 study of neoadjuvant combined modality chemoradiation for distal rectal cancer

Radiosensitizing Effects of Irinotecan versus Oxaliplatin Alone and in Combination with 5-Fluorouracil on Human Colorectal Cancer Cells

To date, oxaliplatin and irinotecan are used in combination with 5-flourouracil (5-FU) for metastatic colorectal cancer. In this study it was tested whether oxaliplatin and irinotecan and their combinations with 5-FU have an enhanced effect when treated simultaneously with ionizing radiation. In addition, it should be compared whether one combination therapy is more effective than the other. Colorectal cancer cells (HT-29) were treated with irinotecan or oxaliplatin, both alone and in combination with 5-FU, and subsequently irradiated. The cell growth, metabolic activity and proliferation of cells were investigated, and the clonogenic survival was determined. Furthermore, the assessment of radiation-induced DNA damage and the influence of the drugs and their combinations on DNA damage repair was investigated. Treatment with irinotecan or oxaliplatin in combination with 5-FU inhibited proliferation and metabolic activity as well as clonogenic survival and the DNA damage repair capacity of the tumor cells. The comparison of oxaliplatin and irinotecan with simultaneous irradiation showed the same effect of both drugs. When oxaliplatin or irinotecan was combined with 5-FU, tumor cell survival was significantly lower than with monotherapy; however, there was no superiority of either combination regimen. Our results have shown that the combination of 5-FU and irinotecan is as effective as the combination of 5-FU with oxaliplatin. Therefore, our data support the use of FOLFIRI as a radiosensitizer.

Hyperfractionation versus Conventional Fractionation of Preoperative Intensity-Modulated Radiotherapy with Oral Capecitabine in Locally Advanced Mid-Low Rectal Cancer: A Propensity Score Matching Study

Purpose

In theory, the hyperfractionated radiotherapy can enhance biological effect dose against tumor and alleviate normal tissue toxicity. This study is to assess the efficacy and safety of preoperative hyperfractionated intensity-modulated radiotherapy (IMRT) with oral capecitabine in patients with locally advanced rectal cancer (LARC).

Methods

We retrospectively screened patients with LARC from January 2015 to June 2016. Patients that received hyperfractionated IMRT or conventional fractionated IMRT were eligible in the hyperfractionation (HF) group or conventional fractionation (CF) group, respectively. The primary outcome was the complete response rate. Secondary outcomes included toxicity, postoperative complications, anus-reservation operation rate, local recurrence and distant metastases rate, overall survival (OS), cancer-specific survival (CSS), and disease-free survival (DFS).

Results

335 patients were included in the analysis. The complete response rate for the hyperfractionated and conventional fractionated IMRT was 20.41% vs. 23.47% (P = 0.583). The anus-reservation operation rate was 68.37% vs. 65.31% (P = 0.649). There were no cases of grade 4 toxicity during radiotherapy; the rate of grade 3 toxicity and postoperative complications was both comparable between groups. However, in the CF group, more patients had a second operation due to complications (0.0% vs. 5.68%, P = 0.011). The cumulative local regional recurrence and distant metastases rates of the HF group and CF group were 5.10% vs. 9.18% (P = 0.267) and 22.45% vs. 24.49% (P = 0.736), respectively. The 5-year OS, CSS, and DFS in the HF group and CF group were 86.45% vs. 73.30% (P = 0.503), 87.34% vs. 75.23% (P = 0.634), and 70.80% vs. 68.11% (P = 0.891), respectively.

Conclusions

The preoperative hyperfractionated IMRT with oral capecitabine, with an acceptable toxicity and favorable response and survival, could reduce the rate of secondary surgery.

Prehabilitation in rectal surgery: a narrative review

AIM

Neoadjuvant chemotherapy (NACRT) can make decompensated patients more vulnerable prior to rectal surgery. Prehabilitation is an intervention which enhances functional capacity to withstand the stress of surgery. The aim of this review was to evaluate the impact of prehabilitation for patients undergoing rectal surgery on physical fitness and clinical outcomes and to establish feasibility of prehabilitation.

METHODS

An analysis of the literature was conducted of PubMed, the Cochrane Library, MEDLINE, EMBASE and ScienceDirect. Articles were initially included based on their title and abstracts reviewed. Full-text copies of those selected were obtained for confirmation of inclusion.

RESULTS

Eight studies were included. Heterogenicity was observed in the structure of exercise programmes. Improvements in physical fitness were observed in six studies. One study demonstrated a statistically significant improvement in quality of life. The prehabilitation programmes were shown to be feasible, with high completion rates. No adverse events were reported. There was limited data regarding the impact of prehabilitation on postoperative outcomes.

CONCLUSION

Current evidence on prehabilitation in rectal surgery has considerable heterogenicity in both structure of programmes and outcome measures. Standardisation is required for future evaluation of the impact on outcomes. A trimodal approach of exercise, nutritional and psychological interventions has been employed in similar programmes, and should be used in rectal surgery. The intervention should be tailored to the patient and environment. This review highlights the benefits, safety and feasibility of prehabilitation and provides a platform for consensus-building for international trials.

Concurrent use of statins and neoadjuvant chemoradiotherapy for rectal cancer: a systematic review and meta-analysis

PURPOSE

Statins are used primarily in patients with cardiovascular disease. More recently, they have demonstrated benefit in oncology patients. In vitro models have shown decreased rectal tumor cell viability in cells receiving chemoradiation and statin therapy. In vivo models have been less clear. This study aims to elucidate the impact of concurrent use of statins on the efficacy of neoadjuvant therapy for rectal cancer.

METHODS

Search of Medline, EMBASE, and CENTRAL was performed. Articles were included if they reported complete pathological response (pCR), long-term oncologic outcomes, or chemoradiotherapy-induced toxicity in patients with rectal cancer receiving concurrent statin and neoadjuvant therapy. A pairwise meta-analyses was performed using inverse variance random effects.

RESULTS

From 1564 citations, six studies with 726 patients on statin therapy (24.5% female, age: 63.6 years) and 1863 patients not on statin therapy (35.6% female, age: 60.9 years) were included. There was no significant difference in pCR rate between patients on statin therapy and patients not on statin therapy (RR 1.23, 95%CI 0.98-1.54, p = 0.08). Similarly, no difference existed between groups in long-term oncologic outcomes (5-year overall survival: RR 1.03, 95%CI 0.86-1.24, p = 0.75; 5-year disease-free survival: RR 1.04, 95%CI 0.85-1.26, p = 0.73). Chemoradiotherapy-induced toxicities were similar between groups.

CONCLUSION

The concurrent use of statin and neoadjuvant therapy did not significantly impact short- or long-term oncologic outcomes in patients with rectal cancer. Yet, despite pooling of data, this study remained inadequately powered. Larger, prospective studies are required to further elucidate the impact of statins on patients undergoing neoadjuvant therapy for rectal cancer.

The association of age with acute toxicities in NRG oncology combined modality lower GI cancer trials

PURPOSE

Expected toxicity from chemoradiation (CRT) is an important factor in treatment decisions but is poorly understood in older adults with lower gastrointestinal (GI) malignancies. Our objective was to compare acute adverse events (AAEs) of older and younger adults with lower GI malignancies treated on NRG studies.

METHODS

Data from 6 NRG trials, testing combined modality therapy in patients with anal or rectal cancer, were used to test the hypothesis that older age was associated with increased AAEs. AAEs and compliance with protocol-directed therapy were compared between patients aged ≥70 and < 70. Categorical variables were compared across age groups using the chi-square test. The association of age on AAEs was evaluated using a covariate-adjusted logistic regression model, with odds ratio (OR) reported. To adjust for multiple comparisons, a p-value <0.01 was considered statistically significant.

RESULTS

There were 2525 patients, including 380 patients ≥70 years old (15%) evaluable. Older patients were more likely to have worse baseline performance status (PS 1 or 2) (23% vs. 16%, p = 0.001), but otherwise baseline characteristics were similar. Older patients were less likely to complete their chemotherapy (78% vs. 87%, p < 0.001), but had similar RT duration. On univariate analysis, older patients were more likely to experience grade ≥ 3 GI AAEs (36% vs. 23%, p < 0.001), and less likely to experience grade ≥ 3 skin AAEs (8% vs. 14%, p = 0.002). On multivariable analysis, older age was associated with grade ≥ 3 GI AAE (OR 1.93, 95% CI: 1.52, 2.47, p < 0.001) after adjusting for sex, race, PS, and disease site.

CONCLUSIONS

Older patients with lower GI cancers who underwent CRT were less likely to complete chemotherapy and had higher rates of grade 3+ GI AAEs. These results can be used to counsel older adults prior to treatment and manage expected toxicities throughout pelvic CRT.

Planning target volume margin assessment for online adaptive MR-guided dose-escalation in rectal cancer on a 1.5 T MR-Linac

PURPOSE

This study assessed the margins needed to cover tumor intrafraction motion during an MR-guided radiotherapy (MRgRT) dose-escalation strategy in intermediate risk rectal cancer.

METHODS

Fifteen patients with rectal cancer were treated with neoadjuvant short-course radiotherapy, 5x5 Gy, according to an online adaptive workflow on a 1.5 T MR-linac. Per patient, 26 3D T2 weighted MRIs were made; one reference scan preceding treatment and five scans per treatment fraction. The primary tumor was delineated on each scan as gross tumor volume (GTV). Target coverage margins were assessed by isotropically expanding the reference GTV until more than 95% of the voxels of the sequential GTVs were covered. A margin with a coverage probability threshold of 90% was defined as adequate. Intra- and interfraction margins to cope with the movement of the GTV in the period between scans were calculated to indicate the target volume margins. Furthermore, the margin needed to cover GTV movement was calculated for different time intervals.

RESULTS

The required margins to cover inter- and intrafraction GTV motion were 17 mm and 6 mm, respectively. Analysis based on time intervals between scans showed smaller margins were needed for adequate GTV coverage as time intervals became shorter, with a 4 mm margin required for a procedure of 15 min or less.

CONCLUSION

The shorter the treatment time, the smaller the margins needed to cover for the GTV movement during an online adaptive MRgRT dose-escalation strategy for intermediate risk rectal cancer. When time intervals between replanning and the end of dose delivery could be reduced to 15 min, a 4 mm margin would allow adequate target coverage.

Complete pathological response in rectal cancer utilising novel treatment strategies for neo-adjuvant therapy: A systematic review

BACKGROUND

Locally advanced rectal cancer is routinely treated with neo-adjuvant long course chemoradiotherapy or short course radiotherapy, followed by total mesorectal excision. Not all patients respond to this treatment and there has been an emergence of novel treatment strategies designed to improve outcomes for these patients. This systematic review aims to assess the current novel neo-adjuvant treatment strategies being utilised in the treatment of patients with rectal cancer and how these impact pathological complete response (pCR) rates.

METHODS

A systematic review of the literature was performed to evaluate pathological response in patients with rectal cancer receiving novel neo-adjuvant therapy. EMBASE and Medline electronic databases were searched for relevant articles. Articles published between January 2008 and February 2019 were retrieved. Included studies underwent critical appraisal and complete pathological response rates were recorded.

RESULTS

Of the initial 1074 articles identified, 217 articles fulfilled the inclusion criteria, of these 60 articles (4359 patients) were included. Neo-adjuvant therapy delivered included novel long course chemoradiation therapy, neoadjuvant chemotherapy alone, addition of a biological agent, total neo-adjuvant therapy, novel short course radiation therapy and studies utilising biomarkers to select patients for therapy. Complete pathological response rates ranged from 0 to 60%.

CONCLUSION

A validated novel neo-adjuvant therapy that significantly increases pCR rates in patients with rectal cancer has not been identified.

Recent advances in (chemo-)radiation therapy for rectal cancer: a comprehensive review

The role of radiation therapy in the treatment of (colo)-rectal cancer has changed dramatically over the past decades. Introduced with the aim of reducing the high rates of local recurrences after conventional surgery, major developments in imaging, surgical technique, systemic therapy and radiation delivery have now created a much more complex environment leading to a more personalized approach. Functional aspects including reduction of acute or late treatment-related side effects, sphincter or even organ-preservation and the unsolved problem of still high distant failure rates have become more important while local recurrence rates can be kept low in the vast majority of patients. This review summarizes the actual role of radiation therapy in different subgroups of patients with rectal cancer, including the current standard approach in different subgroups as well as recent developments focusing on neoadjuvant treatment intensification and/or non-operative treatment approaches aiming at organ-preservation.

Neoadjuvant Radiotherapy Dose Escalation in Locally Advanced Rectal Cancer: a Systematic Review and Meta-analysis of Modern Treatment Approaches and Outcomes

AIMS

Improving pathological complete response (pCR) rates after neoadjuvant chemoradiotherapy for locally advanced rectal cancer may facilitate surgery-sparing treatment paradigms. Radiotherapy boost has been linked to higher rates of pCR; however, outcomes in moderately escalated inverse-planning studies have not been systematically evaluated. We therefore carried out a systematic review and meta-analysis of radiation dose-escalation studies in the context of neoadjuvant therapy for locally advanced rectal cancer.

MATERIALS AND METHODS

A systematic search of Pubmed, EMBASE and Cochrane databases for synonyms of 'rectal cancer', 'radiotherapy' and 'boost' was carried out. Studies were screened for radiotherapy prescription >54 Gy. Prespecified quality assessment was carried out for meta-analysis inclusion suitability. Pooled estimates of pCR, acute toxicity (grade ≥3) and R0 resection rates were determined with random-effects restricted maximum-likelihood estimation. Heterogeneity was assessed with Higgins I² and Cochran Q statistic. Subset analysis examined outcomes in modern inverse-planning studies. Meta-regression with permutation correction was carried out for each outcome against radiation dose, radiotherapy technique, boost technique, chemotherapy intensification and other patient- and treatment-related cofactors.

RESULTS

Forty-nine primary and three follow-up publications were included in the systematic review. Pooled estimates of pCR, toxicity and R0 resection across 37 eligible publications (n = 1817 patients) were 24.1% (95% confidence interval 21.2-27.4%), 11.2% (95% confidence interval 7.2-17.0%) and 90.7% (95% confidence interval 87.9-93.8%). Within inverse-planning studies (17 publications, n = 959 patients), these rates were 25.7% (95% confidence interval 21.0-31.1%), 9.8% (95% confidence interval 4.6-19.7%) and 95.3% (95% confidence interval 91.6-97.4%). Regression analysis did not identify any significant predictor of pCR (P > 0.05).

CONCLUSIONS

Radiotherapy dose escalation above 54 Gy is associated with high rates of pCR and does not seem to increase the risk of acute grade ≥3 toxicity events. pCR rates approaching 25% may be achievable utilising moderate escalation (54-60 Gy) with modern inverse-planning techniques; however, a clear dose-response relationship was not identified in regression analysis and additional evidence is awaited given the prevalence of heterogenous single-arm studies to date.

Pathological Complete Response Following Different Neoadjuvant Treatment Strategies for Locally Advanced Rectal Cancer: A Systematic Review and Meta-analysis

Background

Pathological complete response (pCR) following neoadjuvant treatment for locally advanced rectal cancer (LARC) is associated with better survival, less local recurrence, and less distant failure. Furthermore, pCR indicates that the rectum may have been preserved. This meta-analysis gives an overview of available neoadjuvant treatment strategies for LARC and analyzes how these perform in achieving pCR as compared with the standard of care.

Methods

Pubmed, Embase, and Cochrane Central bibliographic databases were searched. Randomized controlled trials in which patients received neoadjuvant treatment for MRI-staged nonmetastatic resectable LARC were included. The primary outcome was pCR, defined as ypT0N0. A meta-analysis of studies comparing an intervention with standard fluoropyrimidine-based chemoradiation (CRT) was performed.

Results

Of the 17 articles included in the systematic review, 11 were used for the meta-analysis. Addition of oxaliplatin to fluoropyrimidine-based CRT resulted in significantly more pCR compared with fluoropyrimidine-based CRT only (OR 1.46), but at the expense of more ≥ grade 3 toxicity. Other treatment strategies, including consolidation/induction chemotherapy and short-course radiotherapy (SCRT), did not improve pCR rates. None of the included trials reported a benefit in local control or OS. Five-year DFS was significantly worse after SCRT-delay compared with CRT (59% vs. 75.1%, HR 1.93).

Conclusions

All included trials fail to deliver high-level evidence to show an improvement in pCR compared with standard fluoropyrimidine-based CRT. The addition of oxaliplatin might result in more pCR but at the expense of more toxicity. Furthermore, this benefit does not translate into less local recurrence or improved survival.

Electronic supplementary material

The online version of this article (10.1245/s10434-020-08615-2) contains supplementary material, which is available to authorized users.

Dose-time fractionation schedules of preoperative radiotherapy and timing to surgery for rectal cancer

Chemoradiotherapy (CRT) is extensively used prior to surgery for rectal cancer to provide significantly better local control, but the radiotherapy (RT), as the other component of CRT, has been subject to less interest than the drug component in recent years. With considerable developments in RT, the use of advanced techniques, such as intensity-modulated radiotherapy (IMRT) in rectal cancer, is garnering more attention nowadays. The radiation dose can be better conformed to the target volumes with possibilities for synchronous integrated boost without increased complications in normal tissue. Hopefully, both local recurrence and toxicities can be further reduced. Although those seem to be of interest, many issues remain unresolved. There is no international consensus regarding the radiation schedule for preoperative RT for rectal cancer. Moreover, an enormous disparity exists regarding the RT delivery. With the advent of IMRT, variations will likely increase. Moreover, time to surgery is also quite variable, as it depends upon the indication for RT/CRT in the clinical practices. In this review, we discuss the options and problems related to both the dose-time fractionation schedule and time to surgery; furthermore, it addresses the research questions that need answering in the future.

Feasibility of Gold Fiducial Markers as a Surrogate for Gross Tumor Volume Position in Image-Guided Radiation Therapy of Rectal Cancer

PURPOSE

To evaluate the feasibility of fiducial markers as a surrogate for gross tumor volume (GTV) position in image-guided radiation therapy of rectal cancer.

METHODS AND MATERIALS

We analyzed 35 fiducials in 19 patients with rectal cancer who received short-course radiation therapy or long-course chemoradiation therapy. Magnetic resonance imaging examinations were performed before and after the first week of radiation therapy, and daily pre- and postirradiation cone beam computed tomography scans were acquired in the first week of radiation therapy. Between the 2 magnetic resonance imaging examinations, the fiducial displacement relative to the center of gravity of the GTV (COG_GTV) and the COG_GTV displacement relative to bony anatomy were determined. Using the cone beam computed tomography scans, inter- and intrafraction fiducial displacement relative to bony anatomy were determined.

RESULTS

The systematic error of the fiducial displacement relative to the COG_GTV was 2.8, 2.4, and 4.2 mm in the left-right, anterior-posterior (AP), and craniocaudal (CC) directions, respectively. Large interfraction systematic errors of up to 8.0 mm and random errors up to 4.7 mm were found for COG_GTV and fiducial displacements relative to bony anatomy, mostly in the AP and CC directions. For tumors located in the mid and upper rectum, these errors were up to 9.4 mm (systematic) and 5.6 mm (random) compared with 4.9 mm and 2.9 mm for tumors in the lower rectum. Systematic and random errors of the intrafraction fiducial displacement relative to bony anatomy were ≤2.1 mm in all directions.

CONCLUSIONS

Large interfraction errors of the COG_GTV and the fiducials relative to bony anatomy were found. Therefore, despite the observed fiducial displacement relative to the COG_GTV, the use of fiducials as a surrogate for GTV position reduces the required margins in the AP and CC directions for a GTV boost using image-guided radiation therapy of rectal cancer. This reduction in margin may be larger in patients with tumors located in the mid and upper rectum compared with the lower rectum.

Prehabilitation is feasible in patients with rectal cancer undergoing neoadjuvant chemoradiotherapy and may minimize physical deterioration: results from the REx trial

AIM

Rectal cancer patients undergoing neoadjuvant chemoradiotherapy (NACRT) experience physical deterioration and reductions in their quality of life. This feasibility study assessed prehabilitation (a walking intervention) before, during and after NACRT to inform a definitive multi-centred randomized clinical trial (REx trial).

METHODS

Patients planned for NACRT followed by potentially curative surgery were approached (August 2014-March 2016) (www.isrctn.com; 62859294). Prior to NACRT, baseline physical and psycho-social data were recorded using validated tools. Participants were randomized to either the intervention group (exercise counselling session followed by a 13-17 week telephone-guided walking programme) or a control group (standard care). Follow-up testing was undertaken 1-2 weeks before surgery.

RESULTS

Of the 296 screened patients, 78 (26%) were eligible and 48 (61%) were recruited. N = 31 (65%) were men with a mean age of 65.9 years (range 33.7-82.6). Mean intervention duration was 14 weeks with 75% adherence. n = 40 (83%) completed follow-up testing. Both groups recorded reductions in daily walking but the reduction was less in the intervention group although not statistically significant. Participants reported high satisfaction and fidelity to trial procedures.

CONCLUSION

This study demonstrates that prehabilitation is feasible in rectal cancer patients undergoing NACRT. Good recruitment, adherence, retention and patient satisfaction rates support the development of a fully powered trial. The effects of the intervention on physical outcomes were promising.

Phase I/II trial of nano-camptothecin CRLX101 with capecitabine and radiotherapy as neoadjuvant treatment for locally advanced rectal cancer

CRLX101 is a nanoparticle-drug conjugate with a camptothecin payload. We assessed the toxicity and pathologic complete response (pCR) rate of CRLX101 with standard neoadjuvant chemoradiotherapy (CRT) in locally advanced rectal cancer. A single-arm study was conducted with a 3 + 3 dose escalation phase Ib followed by phase II at the maximum tolerated dose (MTD). Thirty-two patients were enrolled with 29 (91%) patients having T3/4 and 26 (81%) N1/2 disease. In phase Ib, no patient experienced a dose limiting toxicity (DLT) with every other week dosing, while 1/9 patients experienced a DLT with weekly dosing. The weekly MTD was identified as 15 mg/m². The most common grade 3-4 toxicity was lymphopenia, with only 1 grade 4 event. pCR was achieved in 6/32 (19%) patients overall and 2/6 (33%) patients at the weekly MTD. CRLX101 at 15 mg/m² weekly with neoadjuvant CRT is a feasible combination strategy with an excellent toxicity profile. Clinicaltrials.gov registration NCT02010567.

MRI-based tumor inter-fraction motion statistics for rectal cancer boost radiotherapy

BACKGROUND

In patients diagnosed with rectal cancer, dose escalation is currently being investigated in a large number of studies. Since there is little known on gross tumor volume (GTV) inter-fraction motion for rectal cancer, a wide variety in margins is used. Purpose of this study is to quantify GTV inter-fraction motion statistics on different timescales and to give estimates of planning target volume (PTV) margins.

MATERIAL AND METHODS

Thirty-two patients, diagnosed with rectal cancer, were included. To investigate motion from week-to-week, 16 patients underwent a pretreatment and five weekly MRIs, prior to a radiotherapy (RT) fraction of the chemoradiotherapy treatment. To investigate motion from day-to-day, the remaining 16 patients underwent five daily MRIs before each fraction in one week of RT. GTV was delineated on all scans according to guidelines. Scans were aligned on bony anatomy with the first MRI. For both datasets separately, GTV inter-fraction motion was determined based on center-of-gravity displacement. Therefrom, systematic and random errors were determined in left/right (LR), anterior/posterior and cranial/caudal (CC) direction. PTV margin estimates were calculated and evaluated on GTV coverage.

RESULTS

Systematic and random errors were found in the range of 2.3-4.8 mm and 1.5-3.3 mm from week-to-week, and 1.8-4.5 mm and 1.8-4.0 mm from day-to-day, respectively. On both timescales, similar motion patterns were found; the most motion was observed in CC whilst the least motion was observed in LR. On the week-to-week data more systematic and less random motion was observed compared to the day-to-day data. Overall, only slight differences in margin estimates were found. Derived PTV margin estimates were found to give adequate GTV coverage.

CONCLUSION

GTV inter-fraction motion, on a week-to-week and day-to-day timescale, can be accounted for using motion statistics presented in this study.

Systematic review of treatment intensification using novel agents for chemoradiotherapy in rectal cancer

BACKGROUND

With the well established shift to neoadjuvant treatment for locally advanced rectal cancer, there is increasing focus on the use of radiosensitizers to improve the efficacy and tolerability of radiotherapy. There currently exist few randomized data exploring novel radiosensitizers to improve response and it is unclear what the clinical endpoints of such trials should be.

METHODS

A qualitative systematic review was performed according to the PRISMA guidelines using preset search criteria across the PubMed, Cochrane and Scopus databases from 1990 to 2017. Additional results were generated from the reference lists of included papers.

RESULTS

A total of 123 papers were identified, of which 37 were included; a further 60 articles were obtained from additional referencing to give a total of 97 articles. Neoadjuvant radiosensitization for locally advanced rectal cancer using fluoropyrimidine-based chemotherapy remains the standard of treatment. The oral derivative capecitabine has practical advantages over 5-fluorouracil, with equal efficacy, but the addition of a second chemotherapeutic agent has yet to show a consistent significant efficacy benefit in randomized clinical assessment. Preclinical and early-phase trials are progressing with promising novel agents, such as small molecular inhibitors and nanoparticles.

CONCLUSION

Despite extensive research and promising preclinical studies, a definite further agent in addition to fluoropyrimidines that consistently improves response rate has yet to be found.

Neoadjuvant Treatment Strategies: Advanced Radiation Alternatives

Long-course chemoradiation therapy (CRT) has been the standard approach for locally advanced rectal tumors. Neoadjuvant CRT is associated to improved local disease control, with less toxicity when compared with adjuvant CRT, as well as the chance for pathologic complete response. The CRT regimens have improved over the past years. This article will examine selected controversies, including novel chemoradiation regimens, duration of radiation (short vs. long course), and radiation techniques such as intensity-modulated radiation therapy (IMRT).

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.

Preoperative radiation dose escalation for rectal cancer using a concomitant boost strategy improves tumor downstaging without increasing toxicity: A matched-pair analysis

Purpose

Pathologic complete response to neoadjuvant chemoradiation therapy (CRT) is associated with improved outcomes for patients with locally advanced rectal cancer (LARC). Increased response rates have been reported with higher radiation doses, but these studies often lack long-term outcome and/or toxicity data. We conducted a case-control analysis of patients with LARC who underwent definitive CRT to determine the efficacy and safety of intensified treatment with a concomitant boost (CB) approach.

Methods and materials

From 1995 to 2003, a phase 2 protocol examined CRT with 5-fluorouracil and CB radiation therapy (52.5 Gy in 5 weeks) for patients with LARC. Seventy-six protocol patients were matched (case-control approach) for surgery type, tumor (T) stage, and clinical nodal (N) stage with patients who received standard dose (SD) CRT (5-fluorouracil, 45 Gy). A chart review was performed. McNemar's test and Kaplan-Meier analyses were used for statistical analysis.

Results

The SD and CB groups did not differ in tumor circumferential involvement and length, but the tumors of CB patients were closer to the anal verge (4.7 vs 5.7 cm; P = .02). Although tumor downstaging was higher in the CB cohort (76% vs 51%; P < .01), pathologic complete response rates did not differ (CB, 17.1% vs SD, 15.8%, P = 1.00). The incidence of grade ≥3 radiation-related toxicities was low and similar in both groups (CB, 10% vs SD, 3%, P = .22). Postoperative (anastomotic leak, wound complications/abscess, bleeding) and late (small bowel obstruction, stricture) complication rates did not differ between the groups (P > .05). The median follow-up was 11.9 years. The 5-year local control rates were higher for CB (100.0%) compared with SD (90.0%) patients (P = .01). CB patients had higher rates of 10-year progression-free survival (71.9% vs 57.6%, P < .01) and overall survival (71.6% vs 62.4%, P = .01) compared with SD patients.

Conclusions

CRT dose escalation for patients with LARC is safe and effective. The improved T-downstaging and local control observed in CB patients should encourage further dose escalation studies.

Organ preservation in rectal cancer - Challenges and future strategies

Neoadjuvant radiochemotherapy with subsequent total mesorectal excision is the standard of care for locally advanced rectal cancer. While this multimodal strategy has decreased local recurrences rates below 5%, long-term morbidities are considerable in terms of urinary, sexual or bowel functioning. At the same time approximately 10–20% of patients have no evidence of residual tumour in their surgical specimen. Pioneering studies from Brazil have suggested that surgery can safely be omitted in carefully selected patients with a clinical complete response after radiochemotherapy. Although confirmatory studies showed similar results, challenges in terms of optimizing radiochemotherapy for organ-preservation, appropriate selection of patients for non-operative management and the safety of this approach remain. The present review will summarize the current data on organ-preservation in rectal cancer and discuss the challenges that need to be addressed in future trials.

Pathologic complete response and disease-free survival are not surrogate endpoints for 5-year survival in rectal cancer: an analysis of 22 randomized trials

BACKGROUND

We performed a literature-based analysis of randomized clinical trials to assess the pathologic complete response (pCR) (ypT0N0 after neoadjuvant therapy) and 3-year disease-free survival (DFS) as potential surrogate endpoints for 5-year overall survival (OS) in rectal cancer treated with neoadjuvant (chemo)radiotherapy (CT)RT.

METHODS

A systematic literature search of PubMed, EMBASE, the Web of Science, SCOPUS, CINAHL, and the Cochrane Library was performed. Treatment effects on 3-year DFS and 5-year OS were expressed as rates of patients alive (%), and those on pCR as differences in pCR rates (∆^pCR%). A weighted regression analysis was performed at individual- and trial-level to test the association between treatment effects on surrogate (∆^pCR% and ∆^3yDFS) and the main clinical outcome (∆^5yOS).

RESULTS

Twenty-two trials involving 10,050 patients, were included in the analysis. The individual level surrogacy showed that the pCR% and 3-year DFS were poorly correlated with 5-year OS (R=0.52; 95% CI, 0.31-0.91; P=0.002; and R=0.60; 95% CI, 0.36-1; P=0.002). The trial-level surrogacy analysis confirmed that the two treatment effects on surrogates (∆^pCR% and ∆^3yDFS) are not strong surrogates for treatment effects on 5-year OS % (R=0.2; 95% CI, -0.29-0.78; P=0.5 and R=0.64; 95% CI, 0.29-1; P=0.06). These findings were confirmed in neoadjuvant CTRT studies but not in phase III trials were 3-year DFS could still represent a valid surrogate.

CONCLUSIONS

This analysis does not support the use of pCR and 3-year DFS% as appropriate surrogate endpoints for 5-year OS% in patients with rectal cancer treated with neoadjuvant therapy.

Effect of increasing radiation dose on pathologic complete response in rectal cancer patients treated with neoadjuvant chemoradiation therapy

BACKGROUND

Neoadjuvant chemoradiation therapy (CRT) increases pathological complete response (pCR) rates compared to radiotherapy alone in patients with stage II-III rectal cancer. Limited evidence addresses whether radiotherapy dose escalation further improves pCR rates. Our purpose is to measure the effects of radiotherapy dose and other factors on post-therapy pathologic tumor (ypT) and nodal stage in rectal cancer patients treated with neoadjuvant CRT followed by mesorectal excision.

MATERIAL AND METHODS

A non-randomized comparative effectiveness analysis was performed of rectal cancer patients treated in 2000-2013 from the National Oncology Data Alliance™ (NODA), a pooled database of cancer registries from >150 US hospitals. The NODA contains the same data submitted to state cancer registries and SEER combined with validated radiotherapy and chemotherapy records. Eligible patients were treated with neoadjuvant CRT followed by proctectomy and had complete data on treatment start dates, radiotherapy dose, clinical tumor (cT) and ypT stage, and number of positive nodes at surgery (n = 3298 patients). Multivariable logistic regression was used to assess the predictive value of independent variables on achieving a pCR.

RESULTS

On multivariable regression, radiotherapy dose, cT stage, and time interval between CRT and surgery were significant predictors of achieving a pCR. After adjusting for the effect of other variates, patients treated with higher radiotherapy doses were also more likely to have negative nodes at surgery and be downstaged from cT3-T4 and/or node positive disease to ypT0-T2N0 after neoadjuvant CRT.

CONCLUSION

Our study suggests that increasing dose significantly improved pCR rates and downstaging in rectal cancer patients treated with neoadjuvant CRT followed by surgery.

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.

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.

Radiation Therapy Intensification for Solid Tumors: A Systematic Review of Randomized Trials

PURPOSE

To systematically review the outcomes of randomized trials testing radiation therapy (RT) intensification, including both dose escalation and/or the use of altered fractionation, as a strategy to improve disease control for a number of malignancies.

METHODS AND MATERIALS

We performed a literature search to identify randomized trials testing RT intensification for cancers of the central nervous system, head and neck, breast, lung, esophagus, rectum, and prostate. Findings were described qualitatively. Where adequate data were available, pooled estimates for the effect of RT intensification on local control (LC) or overall survival (OS) were obtained using the inverse variance method.

RESULTS

In primary central nervous system tumors, esophageal cancer, and rectal cancer, randomized trials have not demonstrated that RT intensification improves clinical outcomes. In breast cancer and prostate cancer, dose escalation has been shown to improve LC or biochemical disease control but not OS. Radiation therapy intensification may improve LC and OS in head and neck and lung cancers, but these benefits have generally been limited to studies that did not incorporate concurrent chemotherapy.

CONCLUSIONS

In randomized trials, the benefits of RT intensification have largely been restricted to trials in which concurrent chemotherapy was not used. Novel strategies to optimize the incorporation of RT in the multimodality treatment of solid tumors should be explored.

Pathologic Response, When Increased by Longer Interval, Is a Marker but Not the Cause of Good Prognosis in Rectal Cancer: 17-year Follow-up of the Lyon R90-01 Randomized Trial

PURPOSE

The Lyon R90-01 randomized trial investigated whether the interval between preoperative radiation therapy and surgery influenced rectal cancer outcome. Long-term results are reported here after a median follow-up of 17 years.

METHODS AND MATERIALS

Between February 1991 and December 1995, 210 patients from 29 French centers were randomly assigned (ratio of 1:1) to groups that waited either 2 weeks (short interval [SI]) or 6 to 8 weeks (long interval [LI]) between neoadjuvant radiation therapy and surgery. The primary endpoint was sphincter-preserving surgery.

RESULTS

LI group showed a better pathologic response (complete response or few residual cells) after radiation therapy than the SI group (26% vs 10.3%, P=.015). A better pathologic response was associated in multivariate analysis with significant improvement of overall survival (pT: P=.0293 and pN: P=.0048) but it was irrespective of the interval duration. The median follow-up was 17.2 years. The 5-, 10-, 15-, and 17-year overall survival rates were, respectively, 66.8%, 48.7%, 40.0%, and 34.0% for the SI group and, respectively, 67.1%, 53.5%, 41.9%, and 34.0% for the LI group. There were no significant differences between groups in terms of survival (P=.7656) or local recurrence rates (SI: 14.4% vs LI: 12.1%, respectively; P=.6202). Of 24 local disease recurrences, 20 (83%) occurred during the first 2 postoperative years, and all but one (96%) occurred during the first 5 postoperative years. The rate of second new malignancies was 9.4% (19 patients).

CONCLUSIONS

The radiation-induced sterilization rate of the preoperative cancer specimen was a marker of good prognosis. The interval duration (the treatment being the same) although it is modifying the sterilization rate has no impact on survival. Radiation therapy did not postpone local recurrence, because the rate of local relapse after 5 years was low. Radiation-induced cancers after radiation therapy were unusual and should not influence treatment decisions in adults.

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.

Clinical outcome of patients with complete pathological response to neoadjuvant chemoradiotherapy for locally advanced rectal cancers: the Indian scenario

Introduction. Neoadjuvant chemoradiotherapy and total mesorectal excision are considered the standard treatment for locally advanced rectal cancer. Various studies have reported pathological downstaging and a complete pathological response rate of 15%-27% following neoadjuvant chemoradiotherapy which has translated into improved survival. We endeavour to determine the clinical outcome of patients attaining a complete pathological tumor response following neoadjuvant chemoradiotherapy in the Indian setting where most of our patient population is younger and presents with aggressive tumor biology. Materials and Methods. Clinicopathological and treatment details were recorded for 64 patients achieving pathological complete response from 2010 to 2013. Disease-free survival (DFS), overall survival (OS), and locoregional and systemic recurrence rates were evaluated for these patients. Results. After a median follow-up of 30.5 months (range 11-59 months), the 3-year overall survival (OS) was 94.6% and the 3-year disease-free survival (DFS) was 88.5%. The locoregional and systemic recurrence rates were 4.7% and 3.1%, respectively. Conclusion. In the Indian subcontinent, despite younger patients with aggressive tumor biology, outcome in complete responders is good.

Trial Watch: Radioimmunotherapy for oncological indications

During the past two decades, it has become increasingly clear that the antineoplastic effects of radiation therapy do not simply reflect the ability of X-, β- and γ-rays to damage transformed cells and directly cause their permanent proliferative arrest or demise, but also involve cancer cell-extrinsic mechanisms. Indeed, among other activities, radiotherapy has been shown to favor the establishment of tumor-specific immune responses that operate systemically, underpinning the so-called 'out-of-field' or 'abscopal' effect. Thus, ionizing rays appear to elicit immunogenic cell death, a functionally peculiar variant of apoptosis associated with the emission of a particularly immunostimulatory combination of damage-associated molecular patterns. In line with this notion, radiation therapy fosters, and thus exacerbates, the antineoplastic effects of various treatment modalities, including surgery, chemotherapy and various immunotherapeutic agents. Here, we summarize recent advances in the use of ionizing rays as a means to induce or potentiate therapeutically relevant anticancer immune responses. In addition, we present clinical trials initiated during the past 12 months to test the actual benefit of radioimmunotherapy in cancer patients.

Clinical review: surgical management of locally advanced and recurrent colorectal cancer

AIM

Recurrent and locally advanced colorectal cancers frequently require en bloc resection of involved organs to achieve negative margins. The aim of this review is to evaluate the most current literature related to the surgical management of locally advanced and recurrent colorectal cancer.

METHODS

A literature review was performed on the electronic databases MEDLINE from PubMed, EMBASE and the Cochrane library for publications in the English language from January 1993 to July 2013. The MeSH search terms 'locally advanced colorectal cancer', 'recurrent colorectal cancer' and 'surgical management' were used.

RESULTS

A total of 1,470 patients with recurrent or locally advanced primary colorectal cancer were included in 22 studies. Surgical removal of the tumour with negative margins (R0) offers the best prognosis in term of survival with a 5-year survival of up to 70 %. MVR is needed in approximately 10 % with the most commonly involved organ being the bladder. The mean post-operative morbidity is 40 %, mainly relating to superficial surgical site infection, pelvic collections and delayed wound healing. Most patients will undergo radiotherapy and/or chemotherapy pre- or post-operatively. The mean 5-year overall survival for R0 resection is 50 % for recurrent and locally advanced primary tumours while survival following R1 or R2 is 12 and <5 %, respectively.

CONCLUSION

Multimodal therapy and extended surgery to achieve clear margins offers good prognosis to patients with recurrent and locally advanced colorectal cancers.

The status of targeted agents in the setting of neoadjuvant radiation therapy in locally advanced rectal cancers

Radiotherapy has a longstanding and well-defined role in the treatment of resectable rectal cancer to reduce the historically high risk of local recurrence. In more advanced borderline or unresectable cases, where the circumferential resection margin (CRM) is breached or threatened according to magnetic resonance imaging (MRI), despite optimized local multimodality treatment and the gains achieved by modern high quality total mesorectal excision (TME), at least half the patients fail to achieve sufficient downstaging with current schedules. Many do not achieve an R0 resection. In less locally advanced cases, even if local control is achieved, this confers only a small impact on distant metastases and a significant proportion of patients (30-40%) still subsequently develop metastatic disease. In fact, distant metastases have now become the predominant cause of failure in rectal cancer. Therefore, increasing the intensity and efficacy of chemotherapy and chemoradiotherapy by integrating additional cytotoxics and biologically targetted agents seems an appealing strategy to explore-with the aim of enhancing curative resection rates and improving distant control and survival. However, to date, we lack validated biomarkers for these biological agents apart from wild-type KRAS. For cetuximab, the appearance of an acneiform rash is associated with response, but low levels of magnesium appear more controversial. There are no molecular biomarkers for bevacizumab. Although some less invasive clinical markers have been proposed for bevacizumab, such as circulating endothelial cells (CECS), circulating levels of VEGF and the development of overt hypertension, these biomarkers have not been validated and are observed to emerge only after a trial of the agent. We also lack a simple method of ongoing monitoring of 'on target' effects of these biological agents, which could determine and pre-empt the development of resistance, prior to radiological and clinical assessessments or even molecular imaging. These shortcomings probably explain our current relative lack of success in the arena of combining these agents with chemoradiation.

Neoadjuvant therapy before surgical treatment

Neoadjuvant treatment in terms of preoperative radiotherapy reduces local recurrence in rectal cancer, but this improvement has little if any impact on overall survival. Currently performed optimal quality-controlled total mesorectal excision (TME) surgery for patients in the trial setting can be associated with very low local recurrence rates of less than 10% whether the patients receive radiotherapy or not. Hence metastatic disease is now the predominant issue. The concept of neoadjuvant chemotherapy (NACT) is a potentially attractive additional or alternative strategy to radiotherapy to deal with metastases. However, randomised phase III trials, evaluating the addition of oxaliplatin at low doses plus preoperative fluoropyrimidine-based chemoradiotherapy (CRT), have in the main failed to show a significant improvement on early pathological response, with the exception of the German CAO/ARO/AIO-04 study. The integration of biologically targeted agents into preoperative CRT has also not fulfilled expectations. The addition of cetuximab appears to achieve relatively low rates of pathological complete responses, and the addition of bevacizumab has raised concerns for excess surgical morbidity. As an alternative to concurrent chemoradiation (which delivers only 5-6 weeks of chemotherapy), potential options include an induction component of 6-12 weeks of NACT prior to radiotherapy or chemoradiation, or the addition of chemotherapy after short-course preoperative radiotherapy (SCPRT) or chemoradiation (defined as consolidation chemotherapy) which utilises the "dead space" of the interval between the end of chemoradiation and surgery, or delivering chemotherapy alone without any radiotherapy.