Concomitant boost radiotherapy and multidrug chemotherapy in the neoadjuvant treatment of locally advanced rectal cancer: results of a phase II study

Understanding the Benefit of Magnetic Resonance-guided Adaptive Radiotherapy in Rectal Cancer Patients: a Single-centre Study

AIMS

Neoadjuvant chemoradiotherapy followed by surgery is the mainstay of treatment for patients with rectal cancer. Standard clinical target volume (CTV) to planning target volume (PTV) margins of 10 mm are used to accommodate inter- and intrafraction motion of target. Treating on magnetic resonance-integrated linear accelerators (MR-linacs) allows for online manual recontouring and adaptation (MRgART) enabling the reduction of PTV margins. The aim of this study was to investigate motion of the primary CTV (CTVA; gross tumour volume and macroscopic nodes with 10 mm expansion to cover microscopic disease) in order to develop a simultaneous integrated boost protocol for use on MR-linacs.

MATERIALS AND METHODS

Patients suitable for neoadjuvant chemoradiotherapy were recruited for treatment on MR-linac using a two-phase technique; only the five phase 1 fractions on MR-linac were used for analysis. Intrafraction motion of CTVA was measured between pre-treatment and post-treatment MRI scans. In MRgART, isotropically expanded pre-treatment PTV margins from 1 to 10 mm were rigidly propagated to post-treatment MRI to determine overlap with 95% of CTVA. The PTV margin was considered acceptable if overlap was >95% in 90% of fractions. To understand the benefit of MRgART, the same methodology was repeated using a reference computed tomography planning scan for pre-treatment imaging.

RESULTS

In total, nine patients were recruited between January 2018 and December 2020 with T3a-T4, N0-N2, M0 disease. Forty-five fractions were analysed in total. The median motion across all planes was 0 mm, demonstrating minimal intrafraction motion. A PTV margin of 3 and 5mm was found to be acceptable in 96 and 98% of fractions, respectively. When comparing to the computed tomography reference scan, the analysis found that PTV margins to 5 and 10 mm only acceptably covered 51 and 76% of fractions, respectively.

CONCLUSION

PTV margins can be reduced to 3-5 mm in MRgART for rectal cancer treatment on MR-linac within an simultaneous integrated boost protocol.

Impact of preoperative chemoradiation with higher dose intensity modulated radiotherapy on pathological complete response for locally advanced rectal cancer: a systematic review

INTRODUCTION

Neoadjuvant chemoradiation (CRT) followed by total mesorectal excision is the current standard-of-care for locally advanced UICC II-III stage rectal cancer (LARC). A pathological complete response (pCR) correlates with survival. Improvements of pCR, including dose escalation, should be explored. The aim of this explorative analysis is to assess the impact on pCR of intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB).

AREAS COVERED

A literature search via PICO (Population, Intervention, Comparison, Outcome) in MEDLINE/PubMed and EMBASE and a systematic review according to PRISMA (Preferred Reporting Items for Systematic Reviews and Metanalysis) methodology were performed. Studies that reported pCR rate in patients with LARC in clinical stage T2N+M0 or cT3/4 N0/+M0 treated with preoperative CRT with SIB-IMRT/VMAT (Volumetric Modulated Arc Therapy) were included. Sixty-two studies were identified, but only eight clinical trials with a total of 311 patients were included . Median follow-up was 16-61 months. pCR reached the value of 38%. Good survival outcomes were observed with a mild toxicity profile.

EXPERT OPINION

Radiotherapy dose intensification in LARC showed a slight increase of pCR compared to historical studies. Prospective evaluations are necessary to define which patients would benefit most.

Treatment Intensification for Locally Advanced Rectal Cancer: Impact on Pathological Complete Response and Outcomes

AIM

Pathological complete response (pCR) and clinical outcomes [overall survival (OS), disease-free survival (DFS), locoregional control (LC)] were evaluated in a single-institution experience of different schedules of neoadjuvant chemoradiotherapy (CRT) for patients with locally advanced rectal cancer (LARC).

PATIENTS AND METHODS

Data for 322 patients with LARC were retrospectively analyzed. pCR was evaluated according to Mandard tumor regression grade (TRG). The Kaplan-Meier method was used to estimate OS, DFS and LC.

RESULTS

Three hundred and three (94.1%) patients underwent surgery. pCR was observed in 81 patients (26.7%), with TRG1-2 rate of 41.8%. The 5- and 10-year OS, DFS and LC rates were 82.5%±2.5% and 65.5%±3.8%, 81.2%±2.4% and 79.3%±2.9%, 93.1%±1.7% and 90.5%±2.1%, respectively.

CONCLUSION

Neoadjuvant CRT in LARC patients resulted in favorable long-term oncological outcomes, with a high pCR rate and acceptable toxicity.

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.

The INTERACT Trial: Long-term results of a randomised trial on preoperative capecitabine-based radiochemotherapy intensified by concomitant boost or oxaliplatin, for cT2 (distal)-cT3 rectal cancer

BACKGROUND AND PURPOSE

Capecitabine-based radiochemotherapy (cbRCT) is standard for preoperative long-course radiochemotherapy of locally advanced rectal cancer. This prospective, parallel-group, randomised controlled trial investigated two intensification regimens. cT4 lesions were excluded.

PRIMARY OBJECTIVE

pathological outcome (TRG 1-2) among arms.

MATERIALS AND METHODS

Low-located cT2N0-2M0, cT3N0-2M0 (up to 12 cm from anal verge) presentations were treated with cbRCT randomly intensified by either radiotherapy boost (Xelac arm) or multidrug concomitant chemotherapy (Xelox arm). Xelac: concomitant boost to bulky site (45 Gy/1.8 Gy/die, 5 sessions/week to the pelvis, +10 Gy at 1 Gy twice/week to the bulky) plus concurrent capecitabine (1650 mg/mq/die). Xelox: 45 Gy to the pelvis + 5.4 Gy/1.8 Gy/die, 5 sessions/week to the bulky site + concurrent capecitabine (1300 mg/mq/die) and oxaliplatin (130 mg/mq on days 1,19,38). Surgery was planned 7-9 weeks after radiochemotherapy.

RESULTS

From June 2005 to September 2013, 534 patients were analysed: 280 in Xelac, 254 in Xelox arm. Xelox arm presented higher G ≥ 3 haematologic (p = 0.01) and neurologic toxicity (p < 0.001). Overall, 98.5% patients received curative surgery. The tumour regression grade distribution did not differ between arms (p = 0.102). TRG 1+2 rate significantly differed: Xelac arm 61.7% vs. Xelox 52.3% (p = 0.039). Pathological complete response (ypT0N0) rates were 24.4 and 23.8%, respectively (p non-significant). Median follow-up:5.62 years. Five-year disease-free survival rate were 74.7% (Xelac) and 73.8% (Xelox), respectively (p = 0.444). Five-year overall survival rate were 80.4% (Xelac) and 85.5% (Xelox), respectively (p = 0.155).

CONCLUSION

Xelac arm significantly obtained higher TRG1-2 rates. No differences were found about clinical outcome. Because of efficacy on TRG, inferior toxicity and good compliance, Xelac schedules or similar radiotherapy dose intensification schemes could be considered as reference treatments for cT3 lesions.

Potential of memory T cells in bridging preoperative chemoradiation and immunotherapy in rectal cancer

The management of locally advanced rectal cancer has passed a long way of developments, where total mesorectal excision and preoperative radiotherapy are crucial to secure clinical outcome. These and other aspects of multidisciplinary strategies are in-depth summarized in the literature, while our mini-review pursues a different goal. From an ethical and medical standpoint, we witness a delayed implementation of novel therapies given the cost/time consuming process of organizing randomized trials that would bridge an already excellent local control in cT3-4 node-positive disease with long-term survival. This unfortunate separation of clinical research and medical care provides a strong motivation to repurpose known pharmaceuticals that suit for treatment intensification with a focus on distant control. In the framework of on-going phase II-III IG/IMRT-SIB trials, we came across an intriguing translational observation that the ratio of circulating (protumor) myeloid-derived suppressor cells to (antitumor) central memory CD8+ T cells is drastically increased, a possible mechanism of tumor immuno-escape and spread. This finding prompts that restoring the CD45RO memory T-cell pool could be a part of integrated adjuvant interventions. Therefore, the immunocorrective potentials of modified IL-2 and the anti-diabetic drug metformin are thoroughly discussed in the context of tumor immunobiology, mTOR pathways and revised Warburg effect.

Pilot Study of Intense Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Cancer: Retrospective Review of a Phase II Study

Aims and Background

Locally advanced rectal adenocarcinoma is typically treated with neoadjuvant chemoradiotherapy and surgery. We assessed the effect of an additional cycle of capecitabine/oxaliplatin chemotherapy before surgery in 57 patients with T3/4, N+/- or T1/2, N+ rectal cancer.

Materials and Study Design

Radiotherapy (total dose, 50.4 Gy) was combined with three cycles of chemotherapy (two cycles concomitant with radiotherapy), and each cycle consisted of oxaliplatin (130 mg/m2 on day 1) and capecitabine (825 mg/m2, twice per day from day 1 to day 14) for 21 days. In addition to assessing the safety of this treatment, the primary endpoint was pathological complete response (pCR). The secondary endpoint was the change in primary tumor and node stage from pre-treatment to post-surgery.

Results

Eleven patients (19%) experienced complete tumor regression and 23 patients (40%) experienced tumor regression grade 3. Tumor down-staging occurred in 31 patients (54.4%) and down-staging of nodes occurred in 25 patients (43.9%). There was a significant difference in tumor stage between pre-treatment and post-surgery (P <0.001). Patients with less advanced N stages had significantly better recurrence-free survival but similar metastasis-free survival and overall survival. Tumor regression grade was not associated with overall survival, recurrence-free survival or metastasis-free survival. The most common adverse events were pulmonary infection (n = 6, 10.5%) and intestinal obstruction (n = 6, 10.5%).

Conclusions

An additional cycle of chemotherapy given after chemoradiotherapy and before surgery provided good efficacy and had a satisfactory safety profile in patients with locally advanced rectal cancer.

Phase 2 Neoadjuvant Treatment Intensification Trials in Rectal Cancer: A Systematic Review

PURPOSE

Multiple phase 2 trials of neoadjuvant treatment intensification in locally advanced rectal cancer have reported promising efficacy signals, but these have not translated into improved cancer outcomes in phase 3 trials. Improvements in phase 2 trial design are needed to reduce these false-positive signals. This systematic review evaluated the design of phase 2 trials of neoadjuvant long-course radiation or chemoradiation therapy treatment intensification in locally advanced rectal cancer.

METHODS AND MATERIALS

The PubMed, EMBASE, MEDLINE, and Cochrane Library databases were searched for published phase 2 trials of neoadjuvant treatment intensification from 2004 to 2016. Trial clinical design and outcomes were assessed, with statistical design and compliance rated using a previously published system. Multivariable meta-regression analysis of pathologic complete response (pCR) was conducted.

RESULTS

We identified 92 eligible trials. Patients with American Joint Committee on Cancer stage II and III equivalent disease were eligible in 87 trials (94.6%). In 43 trials (46.7%), local staging on magnetic resonance imaging was mandated. Only 12 trials (13.0%) were randomized, with 8 having a standard-treatment control arm. Just 51 trials (55.4%) described their statistical design, with 21 trials (22.8%) failing to report their sample size derivation. Most trials (n=84, 91.3%) defined a primary endpoint, but 15 different primary endpoints were used. All trials reported pCR rates. Only 38 trials (41.3%) adequately reported trial statistical design and compliance. Meta-analysis revealed a pooled pCR rate of 17.5% (95% confidence interval, 15.7%-19.4%) across treatment arms of neoadjuvant long-course radiation or chemoradiation therapy treatment intensification and substantial heterogeneity among the reported effect sizes (I² = 55.3%, P<.001). Multivariable meta-regression analysis suggested increased pCR rates with higher radiation therapy doses (adjusted P=.025).

CONCLUSIONS

Improvement in the design of future phase 2 rectal cancer trials is urgently required. A significant increase in randomized trials is essential to overcome selection bias and determine novel schedules suitable for phase 3 testing. This systematic review provides key recommendations to guide future treatment intensification trial design in rectal cancer.

Impact of Duration of Neoadjuvant Radiation on Rectal Cancer Survival: A Real World Multi-center Retrospective Cohort Study

BACKGROUND

The utility of neoadjuvant radiotherapy (nRT) for the treatment of stage II and III rectal cancer is well-established. However, the optimal duration of nRT in this setting remains controversial. Using a population-based cohort of patients with stage II and III rectal cancer (RC) treated with curative intent, our aims were to (1) examine the patterns of nRT use and (2) explore the relationship between different nRT schedules and survival in the real-world setting.

METHODS

This is a multi-center retrospective cohort study based on population-based data from 5 regional comprehensive cancer centers in British Columbia, Canada. We analyzed patients diagnosed with clinical stage II or III RC from 2006 to 2010 and treated with either short-course (SC) or long-course (LC) nRT prior to curative intent surgery. Logistic regression models were constructed to determine the factors associated with the course of nRT delivered to patients. Kaplan-Meier methods and Cox regression that accounted for known prognostic factors were used to evaluate the relationship between nRT schedule and overall (OS), disease-free (DFS), local recurrence-free (LRFS), and distant recurrence-free survival (DRFS).

RESULTS

We identified 427 patients: the median age was 65 years (range, 31 to 94 years), 67% were men, 87% had T3 or T4 tumors, and 74% had N1 or N2 disease. Among them, 241 (56%) received SC and 186 (44%) received LC. Adjusting for confounders, patients with N1 or N2 disease were more likely to undergo LC (odds ratio [OR], 5.08; 95% confidence interval [CI], 2.51-11.22; P < .0001 and OR, 8.35; 95% CI, 3.35-22.39; P < .0001, respectively), whereas older age patients were less likely to receive LC (OR, 0.95; 95% CI, 0.94-0.98; P < .0001). In Kaplan-Meier analysis, there were no significant differences observed in OS, DFS, LRFS, and DRFS between SC and LC. Likewise, multivariate analyses demonstrated that OS (hazard ratio [HR], 0.91; 95% CI, 0.61-1.37; P = .66), DFS (HR, 1.06; 95% CI, 0.68-1.64; P = .80), LRFS (HR, 0.79; 95% CI, 0.39-1.57; P = .50) and DRFS (HR, 0.99; 95% CI, 0.60-1.61; P = .95) were similar regardless of nRT schedules. Additional baseline clinical and tumor characteristics did not influence outcomes (all P > .05).

CONCLUSION

Appropriate preoperative selection of SC versus LC nRT for locally advanced RC based on patient and tumor characteristics was not associated with differences in survival outcomes in the real-world setting.

A Review of Neoadjuvant Chemoradiotherapy for Locally Advanced Rectal Cancer

Neoadjuvant chemoradiotherapy has become the standard treatment for locally advanced rectal cancer. Neoadjuvant chemoradiotherapy not only can reduce tumor size and recurrence, but also increase the tumor resection rate and anus retention rate with very slight side effect. Comparing with preoperative chemotherapy, preoperative chemoradiotherapy can further reduce the local recurrence rate and downstage. Middle and low rectal cancers can benefit more from neoadjuvant chemradiotherapy than high rectal cancer. It needs to refine the selection of appropriate patients and irradiation modes for neoadjuvant chemoradiotherapy. Different therapeutic reactions to neoadjuvant chemoradiotherapy affect the type of surgical techniques, hence calling for the need of much attention. Furthermore, many problems such as accurate staging before surgery, selection of suitable neoadjuvant chemoradiotherapy method, and sensitivity prediction to preoperative radiotherapy need to be well settled.

Preoperative Chemoradiation With VMAT-SIB in Rectal Cancer: A Phase II Study

PURPOSE

The aim of this study was to investigate the efficacy and toxicity of volumetric modulated arc therapy (VMAT)-simultaneous integrated boost (SIB) in preoperative combined treatment of locally advanced rectal cancer.

METHODS

Radiation therapy was performed using the VMAT-SIB technique. The dose to mesorectum and pelvic lymph nodes was 45 Gy (1.8 Gy/fraction). A concomitant boost was delivered on GTV + 2-cm margin with a total dose of 57.5 Gy (2.3 Gy/fraction). The following concomitant chemotherapy was administered: capecitabine (825 mg/m² twice daily, 5 days per week) and oxaliplatin (130 mg/m² on days 1, 17, and 35). Efficacy was evaluated in terms of complete pathological response (pCR). Acute toxicities were evaluated according to Common Terminology Criteria for Adverse Events version 3.0 criteria.

RESULTS

A total of 18 patients (7 women; median age 62 years; clinical stage: 4 local recurrences, 6 cT4, 5 cT3, 3 cT2, 2 cN0, 7 cN1, 9 cN2) were enrolled. Sixteen patients underwent surgical resection (9 low anterior resection, 6 abdominal perineal amputations; 1 transanal excision) and 2 patients did not undergo surgery for early metastatic progression or death from acute pulmonary edema. R0 resection was achieved in all patients who underwent surgery. Overall, 4 patients had a pCR and 7 patients only a microscopic residual of disease (pT0-Tmic: 11/18 = 61.1%; 95% CI, 36.2-86.1). Acute grade ≥ 3 toxicity was as follows: 1 case of leukopenia, 1 skin toxicity, 1 genitourinary toxicity, and 5 gastrointestinal toxicities, with an overall incidence of 8 (44.4%) of 18 patients. One-, 3-, and 5-year cumulative local control was 100%, 68.6%, and 68.6%, respectively. One-, 3-, and 5-year cumulative disease-free survival was 88.9%, 66.7%, and 66.7%, respectively. One-, 3-, and 5-year cumulative overall survival was 85%, 63.8%, and 63.8%, respectively.

CONCLUSION

The regimen used in this study showed excellent results in terms of pathologic responses. However, despite the use of the VMAT technique, more than one-third of patients had severe acute toxicity.

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.

Neoadjuvant chemoradiation with concomitant boost radiotherapy associated to capecitabine in rectal cancer patients

PURPOSE

The primary end-points were complete pathological response and local control. Secondary end-points were survivals, anal sphincter preservation, and toxicity profile.

METHODS

Patients with T3/T4 and or N+ rectal cancer (n = 65) were treated with preoperative concomitant boost radiotherapy (55 Gy/25 fractions) associated to concurrent chemotherapy with oral capecitabine.

RESULTS

All patients completed the programmed treatment. The complete pathological response was achieved by 17 % of the patients. Anal sphincter preservation surgery was possible for 86 % of the patients with low rectal cancer (≤ 5 cm from the anal verge). The T-stage and N-stage downstaging were achieved by 40 and 58 % of the patients, respectively. Circumferential radial margin was involved (close/positive) in eight patients. After a median follow-up of 26 months, local and distant recurrence occurred in two and 11 patients, respectively. The 3-year overall survival and disease-free survival were 86.8 and 81 %, respectively. Non-hematological ≥ grade 3 toxicities were observed in 15 % of the patients. On univariate analysis N-downstaging and positive circumferential radial margin were significantly associated with worse overall survival (p = 0.003 and p = 0.023, respectively), disease-free survival (p = 0.001 and p = 0.036, respectively), and metastasis-free survival (MFS) (p = 0.001 and p = 0.038, respectively).On multivariate analysis, the N-downstaging were significantly associated with better overall survival (OS) (p = 0.022).

CONCLUSIONS

Our data support the efficacy of preoperative treatment for rectal cancer in terms of local outcomes. Radiation treatment intensification may have a biological rationale; longer follow-up is needed.

Concomitant boost IMRT-based neoadjuvant chemoradiotherapy for clinical stage II/III rectal adenocarcinoma: results of a phase II study

AIM

This study was designed to evaluate the efficacy and toxicities of concomitant boost intensity-modulated radiation therapy (IMRT) along with capecitabine and oxaliplatin, followed by a cycle of Xelox, in neoadjuvant course for locally advanced rectal cancer.

MATERIALS AND METHODS

Patients with histologically confirmed, newly diagnosed, locally advanced rectal adenocarcinoma (cT3-T4 and/or cN+) located within 12 cm of the anal verge were included in this study. Patients received IMRT to the pelvis of 50 Gy and a concomitant boost of 5 Gy to the primary tumor in 25 fractions, and concurrent with oxaliplatin (50 mg/m2 d1 weekly) and capecitabine (625 mg/m2 bid d1-5 weekly). One cycle of Xelox (oxaliplatin 130 mg/m2 on d1 and capecitabine 1000 mg/m2 twice daily d1-14) was given two weeks after the completion of chemoradiation, and radical surgery was scheduled eight weeks after chemoradiation. Tumor response was evaluated by tumor regression grade (TRG) system and acute toxicities were evaluated by NCI-CTC 3.0 criteria. Survival curves were estimated using the Kaplan-Meier method and compared with Log-rank test.

RESULTS

A total of 78 patients were included between March 2009 and May 2011 (median age 54 years; 62 male). Seventy-six patients underwent surgical resection. Twenty-eight patients underwent sphincter-sparing lower anterior resection and 18 patients (23.7%) were evaluated as pathological complete response (pCR). The incidences of grade 3 hematologic toxicity, diarrhea, and radiation dermatitis were 3.8%, 10.3%, and 17.9%, respectively. The three-year LR (local recurrence), DFS (disease-free survival) and OS (overall survival) rates were 14.6%, 63.8% and 77.4%, respectively. Initial clinical T stage and tumor regression were independent prognostic factors to DFS.

CONCLUSION

An intensified regimen of concomitant boost radiotherapy plus concurrent capecitabine and oxaliplatin, followed by one cycle of Xelox, can be safely administered in patients with locally advanced rectal cancer, and produces a high rate of pCR. A prognostic score model is helpful to distinguish different long-term prognosis groups in early stage.

Anti-miRNA-221 sensitizes human colorectal carcinoma cells to radiation by upregulating PTEN

AIM: To investigate the regulative effect of miRNA (miR)-221 on colorectal carcinoma (CRC) cell radiosensitivity and the underlying mechanisms.

METHODS: A human CRC-derived cell line was cultured conventionally and exposed to different doses of X-rays (0, 2, 4, 6 and 8 Gy). The total RNA and protein of the cells were extracted 24 h after irradiation, and the alteration of miR-221 and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) gene mRNA expression was detected by real-time reverse transcriptase polymerase chain reaction (PCR). The protein alteration of PTEN in the cells was detected by Western blotting. Caco2 cells were pretreated with or without anti-PTEN-siRNA prior to the addition of pre-miR-221 or anti-miR-221 using Lipofectamine 2000. Colony formation assay and flow cytometry analysis were used to measure the surviving cell fraction and the sensitizing enhancement ratio after irradiation. Additionally, PTEN 3′-untranslated region fragment was PCR amplified and inserted into a luciferase reporter plasmid. The luciferase reporter plasmid construct was then transfected into CRC cells together with pre-miR-221 or anti-miR-221, and the luciferase activity in the transfected cells was detected.

RESULTS: The X-ray radiation dose had a significant effect on the expression of miR-221 and PTEN protein in human Caco2 cells in a dose-dependent manner. The miR-221 expression level improved gradually with the increase in irradiation dose, while the PTEN protein expression level reduced gradually. miR-221 expression was significantly reduced in the anti-miR-221 group compared with the pre-miR-221 and negative control groups (P < 0.01). Anti-miR-221 upregulated expression of PTEN protein and enhanced the radiosensitivity of Caco2 cells (P < 0.01). Moreover, the inhibitory effect was dramatically abolished by pretreatment with anti-PTEN-siRNA, suggesting that the enhancement of radiosensitivity was indeed mediated by PTEN. A significant increase of luciferase activity was detected in CRC cells that were cotransfected with the luciferase reporter plasmid construct and anti-miR-221 (P < 0.01).

CONCLUSION: Anti-miR-221 can enhance the radiosensitivity of CRC cells by upregulating PTEN.

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.

Targeting thymidylate synthase in colorectal cancer: critical re-evaluation and emerging therapeutic role of raltitrexed

INTRODUCTION

5-fluorouracil continues to be the cornerstone of treatment for colorectal cancer. Although fluoropyrimidines are generally considered as well-tolerated drugs, severe toxicities can be a major clinical problem, and the recommended prolonged infusion of 5-fluorouracil provokes discomfort in patients. Raltitrexed (Tomudex), a quinazoline analogue of folinic acid, is a selective and direct thymidylate synthase (TS) inhibitor with a convenient 3-weekly schedule of administration.

AREAS COVERED

In this review, through critical insight into the mechanism of action and main clinical experiences, the authors suggest the necessity to reconsider raltitrexed as a valuable anticancer drug and as a suitable option for colorectal cancer. The authors highlight its emerging therapeutic role in clinical practice for patients with fluoropyrimidine-induced cardiotoxicity or a significant history of cardiac disease.

EXPERT OPINION

This review discusses if TS could still be a relevant target for colorectal cancer in the era of molecular therapy and if raltitrexed should still be considered a drug with a life-threatening toxicity. Furthermore, this review discusses the principal combination clinical experiences of raltitrexed and its emerging therapeutic role in clinical practice as a suitable option for colorectal cancer patients with fluoropyrimidine-induced cardiotoxicity or a significant history of cardiac disease.

Phase II trial of first-line chemoradiotherapy with intensity-modulated radiation therapy followed by chemotherapy for synchronous unresectable distant metastases rectal adenocarcinoma

Aims

Based on the hypothesis that first-line chemoradiation followed by chemotherapy was superior for primary tumor and non-inferior for distant lesions compared to chemotherapy alone in synchronous unresectable distant metastases rectal adenocarcinoma, this study was designed to assess the efficacy and safety of this strategy.

Materials and methods

Thirty two eligible patients received intensity modulated radiation therapy (45 Gy to the pelvis and a concomitant 10 Gy boost to the gross tumor), along with concurrent weekly capecitabine and oxaliplatin. Patients underwent radical surgery if all lesions were visually evaluated as resectable and received chemotherapy for a total of 6 months, whether pre- or post-operatively (definitive therapy group). The remaining patients received 6 months of consolidation chemotherapy followed by maintenance chemotherapy (non-definitive therapy group).

Results

The toxicities were acceptable, with radiation-induced dermatitis around the anal verge being the most common (18.8%). Fourteen patients underwent surgical resection of the rectal tumor, with 5 (35.7%) experiencing a pathological complete response. Nine out of 14 received definitive treatment, defined as R0 resections of all visible tumors. At a median follow-up of 12 months (range, 4–23 months), 2 cases were evaluated as local failure, and the median overall survival (OS) and progression free survival (PFS) for all 32 patients were 17.5 and 12 months, respectively. OS differed significantly in the definitive and non-definitive therapy groups (p=0.045), and PFS tended to differ (p=0.274).

Conclusion

It was demonstrated that the strategy of first-line chemoradiation followed by chemotherapy was effective and tolerable, especially for local control. OS and PFS were superior in patients who did than did not undergo curative therapy.

Patients with rectal cancer receiving adjuvant chemotherapy have an increased survival: a population-based longitudinal study

BACKGROUND

The aim of this study was to investigate whether or not the use of adjuvant chemotherapy in stage III rectal cancer varies between regions and over time, and if this has had an effect on survival rates.

PATIENTS AND METHODS

Patients from the Uppsala/Örebro region below 75 years-of-age, operated 1995-2002 and registered in the Swedish Rectal Cancer Register, were monitored between 1995 and September 2008. A multivariate Cox proportional hazard regression model was used for analysis. Overall survival was described using the Kaplan-Meier method.

RESULTS

Four hundred and thirty-six patients with stage III rectal cancer were included. Adjuvant chemotherapy was given to 42% of the patients (proportions varying from 13% to 77% among counties), and there were substantial increases over time. The 5-year overall survival was 65.8% [95% confidence interval (CI) 50-84] for patients having adjuvant chemotherapy compared with 45.6% (95% CI 39-52) for patients not treated with chemotherapy. The multivariate hazard ratio for death was 0.65 (95% CI 0.5-0.8) for patients treated with adjuvant chemotherapy.

CONCLUSIONS

The use of adjuvant chemotherapy for rectal cancer has increased, but varies considerably between hospitals/counties. In this cohort, those having adjuvant chemotherapy had a longer overall survival.

Multidisciplinary treatment of patients with rectal cancer: Development during the past decades and plans for the future

In rectal cancer treatment, both the local primary and the regional and systemic tumour cell deposits must be taken care of in order to improve survival. The three main treatments, surgery, radiotherapy, and chemotherapy, each with their own advantages and limitations, must then be combined to improve results. Several large randomized trials have shown that combinations of the modalities have markedly reduced the loco-regional recurrences, but have not yet had any major influence on overall survival. 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, treatment of rectal cancer is administered to populations of individuals, based upon clinical factors and imaging, and can presently not be further individualized. There is an urgent need to develop response predictors.