The current landscape of locally advanced rectal cancer

Postoperative adjuvant chemoradiotherapy was recommended as the standard treatment for patients with rectal cancer because it reduces local recurrence. This paradigm shifted with the use of neoadjuvant chemoradiotherapy, which not only reduces local recurrence but also improves sphincter preservation and surgical outcomes. However, the treatment of rectal carcinoma remains complicated. The accuracy of tumor staging can be compromised depending on the imaging modality used. The addition of modern chemotherapeutics and biologics to 5-fluorouracil as radiation sensitizers is questionable. Oxaliplatin as a radiation sensitizer has minimal effects on the pathologic complete response, but improves the radiographical response at the expense of an increased risk of toxicities. The role of biologics in addition to radiation therapy continues to be explored. Attention has focused on improving diagnostic imaging, radiation oncology, and surgical techniques, treatment regimens, and on exploring a role of molecular markers for patients with rectal cancers. We review the pivotal trials that have led to the current treatment paradigm for locally advanced rectal cancer and discuss novel methodologies that are being developed for the treatment of this prevalent malignancy.

Radiation, chemotherapy and biological therapy in the curative treatment of locally advanced rectal cancer

OBJECTIVE

To review the published evidence relating to the use of radiotherapy (RT), chemotherapy and biological therapy as adjuncts to surgery in the curative treatment of rectal cancer.

METHODS

Searches were carried out of the MEDLINE and CANCERLIT databases together with conference abstracts from key meetings including the American Society of Clinical Oncology Annual Meeting and Gastrointestinal Cancers Symposium and the ECCO/ESMO Multidisciplinary Congress.

RESULTS

RT reduces local pelvic recurrence when used as an adjunct to surgery, even when this is performed optimally by total mesorectal excision (TME). RT is usually given as short-course preoperative radiotherapy (SCPRT) followed by immediate surgery which produces no or very little downstaging or long-course concurrent chemoradiation (CRT) followed by a 6-8 week gap prior to surgery which produces significant downstaging. The prognostic importance of achieving a clear histological circumferential resection margin is now well recognised and pathological assessment of the quality of surgery can predict long-term outcomes. Internationally there is considerable heterogeneity in the staging modalities and criteria used in deciding which approach might be used, in the reporting of histological results and in RT parameters (time/dose/fractionation/volume). Attempts to increase the potency of CRT have included the addition of concurrent chemotherapeutic and biological agents to the standard fluoropyrimidine although there is little randomised data and none with regard to long-term survival outcomes. Neither SCPRT nor downstaging CRT have been shown to reduce the rate of subsequent distant metastatic relapse which remains a significant clinical problem. The potential additional benefit of neoadjuvant or adjuvant chemotherapy in addition to SCPRT or long-course CRT remains ill-defined. Late morbidity can include bowel and sexual dysfunction, pelvic fractures and second malignancies with considerably more being known in relation to SCPRT than long-course CRT.

CONCLUSIONS

Improvements in imaging, pathology and surgical technique combined with multimodality treatment using RT and chemotherapy are leading to continuing improvements in the long term outcome for patients with rectal cancer although much remains to be learnt regarding the optimum strategy for use of these in different clinical contexts and their relationship to long-term morbidity.

Preoperative chemoradiation with irinotecan and capecitabine in patients with locally advanced resectable rectal cancer: long-term results of a Phase II study

PURPOSE

Preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer has shown benefit over postoperative CRT; however, a standard CRT regimen has yet to be defined. We performed a prospective concurrent CRT Phase II study with irinotecan and capecitabine in patients with locally advanced rectal cancer to investigate the efficacy and safety of this regimen.

METHODS AND MATERIALS

Patients with locally advanced, nonmetastatic, and mid-to-lower rectal cancer were enrolled. Radiotherapy was delivered in 1.8-Gy daily fractions for a total of 45 Gy in 25 fractions, followed by a coned-down boost of 5.4 Gy in 3 fractions. Concurrent chemotherapy consisted of 40 mg/m(2) of irinotecan per week for 5 consecutive weeks and 1,650 mg/m(2) of capecitabine per day for 5 days per week (weekdays only) from the first day of radiotherapy. Total mesorectal excision was performed within 6 ± 2 weeks. The pathologic responses and survival outcomes were included for the study endpoints.

RESULTS

In total, 48 patients were enrolled; 33 (68.7%) were men and 15 (31.3%) were women, and the median age was 59 years (range, 32-72 years). The pathologic complete response rate was 25.0% (11 of 44; 95% confidence interval, 12.2-37.8) and 8 patients (18.2% [8 of 44]) showed near-total tumor regression. The 5-year disease-free and overall survival rates were 75.0% and 93.6%, respectively. Grade 3 toxicities included leukopenia (3 [6.3%]), neutropenia (1 [2.1%]), infection (1 [2.1%]), alanine aminotransferase elevation (1 [2.1%]), and diarrhea (1 [2.1%]). There was no Grade 4 toxicity or treatment-related death.

CONCLUSIONS

Preoperative CRT with irinotecan and capecitabine with treatment-free weekends showed very mild toxicity profiles and promising results in terms of survival.

Phase I study of preoperative chemoradiation with s-1 and oxaliplatin in patients with locally advanced resectable rectal cancer

PURPOSE

To perform a Phase I study of preoperative chemoradiation (CRT) with S-1, a novel oral fluoropyrimidine, plus oxaliplatin in patients with locally advanced rectal cancer, to determine the maximum tolerated dose and the recommended dose.

METHODS AND MATERIALS

Radiotherapy was delivered to a total of 45 Gy in 25 fractions and followed by a coned-down boost of 5.4 Gy in 3 fractions. Concurrent chemotherapy consisted of a fixed dose of oxaliplatin (50 mg/m2/week) on Days 1, 8, 22, and 29 and escalated doses of S-1 on Days 1-14 and 22-35. The initial dose of S-1 was 50 mg/m2/day, gradually increasing to 60, 70, and 80 mg/m2/day. Surgery was performed within 6±2 weeks.

RESULTS

Twelve patients were enrolled and tolerated up to Dose Level 4 (3 patients at each dose level) without dose-limiting toxicity. An additional 3 patients were enrolled at Dose Level 4, with 1 experiencing a dose-limiting toxicity of Grade 3 diarrhea. Although maximum tolerated dose was not attained, Dose Level 4 (S-1 80 mg/m2/day) was chosen as the recommended dose for further Phase II studies. No Grade 4 toxicity was observed, and Grade 3 toxicities of leukopenia and diarrhea occurred in the same patient (1 of 15, 6.7%). Pathologic complete responses were observed in 2 of 15 patients (13.3%).

CONCLUSIONS

The recommended dose of S-1 was determined to be 80 mg/m2/day when combined with oxaliplatin in preoperative CRT, and a Phase II trial is now ongoing.

Cetuximab and chemoradiation for rectal cancer--is the water getting muddy?

The epidermal growth factor receptor (EGFR) inhibitor cetuximab has been successfully combined with radical radiotherapy in head and neck cancer. In colorectal cancer, increased response rates are achieved by cetuximab and panitumumab within standard chemotherapy schedules, but not in chemoradiation regimens. This review examines the clinical evidence and potential mechanisms for an interaction when EGFR inhibitors are added to fluoropyrimidine-based chemoradiation in rectal adenocarcinoma.

METHODS

This review was compiled by searching PubMed and Medline for English language articles published until 2009 with established search strategies, supplemented by hand searching of abstracts from the proceedings of relevant international meetings. The primary outcome measure was pathological complete response (pCR).

RESULTS

Only 13 publications and three presentations in abstract of 13 phase I/II trials of preoperative chemoradiation with cetuximab in rectal cancer were identified. A total of 316 patients were identified who received cetuximab in combination with radiotherapy and 5-fluorouracil or capecitabine preoperatively. One hundred and thirty eight of these patients received either additional irinotecan or oxaliplatin. One study with panitumumab with safety but no efficacy results was identified, and two studies with gefinitib. The pCR rate ranged from 0-20%. The overall pooled pCR for cetuximab based chemoradiation was 9.1% (29/316). The rate of G3/G4 gastrointestinal toxicity, in terms of diarrhoea, varied from 5-30%, with an overall pooled rate of 47/313 (15%).

DISCUSSION

Potential reasons for the disappointing results of EGFR inhibition with fluoropyrimidine-based preoperative chemoradiation include a less critical role of repopulation in rectal adenocarcinoma using a non-curative radiation dose; or antagonistic effects on 5FU-based chemoradiation and oxaliplatin, if some cells arrest in G1 or G2-M and fail to pass through S phase.

CONCLUSION

Cetuximab combined with fluoropyrimidine-based chemoradiation is not currently recommended. A better understanding of the mechanisms involved in combinations of chemotherapy and radiotherapy might allow more effective future scheduling of biological and chemical agents in combination with radiation.

Phase II study of preoperative chemoradiotherapy (CRT) with irinotecan plus S-1 in locally advanced rectal cancer

BACKGROUND AND PURPOSE

The aim of this study is to evaluate the efficacy and safety of preoperative radiation therapy combined with S-1 and irinotecan (SI) in LARC.

MATERIALS AND METHODS

Patients were considered LARC if they had a T3/T4 lesion or node positive. Weekly doses of 40 mg/m(2) irinotecan were intravenously administered once per week during weeks 1-5 of radiotherapy. S-1 (70 mg/m(2)) was given from Monday to Friday in all weeks of radiotherapy. 3-D conformal radiotherapy was given at daily fractions of 1.8Gy for 5days for a total dose of 50.4 (45+5.4)Gy. Surgery was performed 4-6 weeks following the completion of chemoradiation.

RESULTS

Between June 2006 and November 2007, 43 pts were enrolled. The stage was: cT3 24 patients, cT4 6 patients; 28 patients were cN+. Forty-one patients completed the chemoradiation and 42 patients underwent operation: a low anterior resection was performed in 36 patients, a total colectomy in 1 patient, and an abdominal perineal resection in 5 patients. T downstaging was observed in 50%; 23 N+ patients became N- (55%). The complete pathological response was observed in 9 patients (21%). The 3-year locoregional failure rate, distant failure rate, disease-free survival, and overall survival were 9.5%, 18.6%, 72.1%, and 94.3%, respectively. Only three patients experienced G3 diarrhea; one had G3 sepsis and two had septic shock. Hematological toxicity (G3-G4) was observed in five patients.

CONCLUSIONS

This study demonstrated the efficacy of preoperative CRT with S-1 and irinotecan with 21% of complete response. However, prompt recognition and management of infection is needed to use it in patients with locally advanced rectal cancer.

Phase II, randomized study of concomitant chemoradiotherapy followed by surgery and adjuvant capecitabine plus oxaliplatin (CAPOX) compared with induction CAPOX followed by concomitant chemoradiotherapy and surgery in magnetic resonance imaging-defined, locally advanced rectal cancer: Grupo cancer de recto 3 study

PURPOSE The optimal therapeutic sequence of the adjuvant chemotherapy component of preoperative chemoradiotherapy (CRT) for patients with locally advanced rectal cancer is controversial. Induction chemotherapy before preoperative CRT may be associated with better efficacy and compliance. PATIENTS AND METHODS A total of 108 patients with locally advanced rectal cancer were randomly assigned to arm A-preoperative CRT with capecitabine, oxaliplatin, and concurrent radiation followed by surgery and four cycles of postoperative adjuvant capecitabine and oxaliplatin (CAPOX)-or arm B-induction CAPOX followed by CRT and surgery. The primary end point was pathologic complete response rate (pCR). Results On an intention-to-treat basis, the pCR for arms A and B were 13.5% (95% CI, 5.6% to 25.8%) and 14.3% (95% CI, 6.4% to 26.2%), respectively. There were no statistically significant differences in other end points, including downstaging, tumor regression, and R0 resection. Overall, chemotherapy treatment exposure was higher in arm B than in arm A for both oxaliplatin (P < .0001) and capecitabine (P < .0001). During CRT, grades 3 to 4 adverse events were similar in both arms but were significantly higher in arm A during postoperative adjuvant CT than with induction CT in arm B. There were three deaths in each arm during the treatment period. CONCLUSION Compared with postoperative adjuvant CAPOX, induction CAPOX before CRT had similar pCR and complete resection rates. It did achieve more favorable compliance and toxicity profiles. On the basis of these findings, a phase III study to definitively test the induction strategy is warranted.

Chemoradiotherapy with 5-fluorouracil/leucovorin, surgery and adjuvant chemotherapy for locally advanced rectal cancer

The aim of this study was to demonstrate a pathologic complete response (pCR) rate of at least 10% with an acceptable toxicity achieved by preoperative chemoradiotherapy with 5-fluorouracil (5-FU)/leucovorin in patients with locally advanced rectal cancer. Patients were treated by radiotherapy targeting 50 Gy and 5-FU/leucovorin intravenously during the 1st, 4th and 7th week after start of radiotherapy followed by surgery and adjuvant chemotherapy. In 71 evaluable patients, the pCR rate was 14.1% (95% CI, 6.0-22.2); the local relapse rate, 6.1%; the 5-year disease-free survival, 54% and the overall 5-year survival, 68%. The most severe adverse events were neutropenia (17%), diarrhoea (17%), infection (8%) and fatal cardiovascular function (1%). This therapy yielded a high rate of pCR, a low rate of local relapse and a long disease-free and overall survival. To increase its feasibility, radiation dose reduction to 45 Gy and administration of only two preoperative cycles of chemotherapy is recommended.