Adaptive radiation dose escalation in rectal adenocarcinoma: a review.
ABSTRACT: 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.
Project description: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.
Project description:BACKGROUND: To evaluate the safety of focal dose escalation to regions with standardized uptake value (SUV) >2.0 using intensity-modulated radiation therapy (IMRT) by comparison of radiotherapy plans using dose-volume histograms (DVHs) and normal tissue complication probability (NTCP) for postoperative local recurrent rectal cancer METHODS: First, we performed conventional radiotherapy with 40 Gy/20 fr. (CRT 40 Gy) for 12 patients with postoperative local recurrent rectal cancer, and then we performed FDG-PET/CT radiotherapy planning for those patients. We defined the regions with SUV > 2.0 as biological target volume (BTV) and made three boost plans for each patient: 1) CRT boost plan, 2) IMRT without dose-painting boost plan, and 3) IMRT with dose-painting boost plan. The total boost dose was 20 Gy. In IMRT with dose-painting boost plan, we increased the dose for BTV+5 mm by 30% of the prescribed dose. We added CRT boost plan to CRT 40 Gy (summed plan 1), IMRT without dose-painting boost plan to CRT 40 Gy (summed plan 2) and IMRT with dose-painting boost plan to CRT 40 Gy (summed plan 3), and we compared those plans using DVHs and NTCP. RESULTS: D(mean) of PTV-PET and that of PTV-CT were 26.5 Gy and 21.3 Gy, respectively. V50 of small bowel PRV in summed plan 1 was significantly higher than those in other plans ((summed plan 1 vs. summed plan 2 vs. summed plan 3: 47.11 +/- 45.33 cm3 vs. 40.63 +/- 39.13 cm3 vs. 41.25 +/- 39.96 cm3 (p < 0.01, respectively)). There were no significant differences in V30, V40, V60, D(mean) or NTCP of small bowel PRV. CONCLUSIONS: FDG-PET-guided IMRT can facilitate focal dose-escalation to regions with SUV above 2.0 for postoperative local recurrent rectal cancer.
Project description:BACKGROUND:This study was designed to explore whether an intensified chemoradiotherapy (CRT) led to a better clinical outcome in locally advanced rectal cancer. METHODS:Patients with stage II/III rectal cancer were randomly allocated to receive either pelvic intensity-modulated radiation therapy (IMRT) of 50?Gy/25Fx concurrently with capecitabine and oxaliplatin (Arm A), or pelvic radiation of 50?Gy/25Fx with a concomitant boost of 5?Gy to the primary lesion, followed by a cycle of XELOX 2 weeks after the end of CRT (Arm B). All patients were planned to receive a definitive operation 8?weeks after the completion of CRT and a total of six perioperative chemotherapy cycles of capecitabine and oxaliplatin regardless of pathological result. Pathological complete response (ypCR) was the primary endpoint. RESULTS:From February 2010 to December 2011, 120 patients from three centers were enrolled in this study. Ninety-five percent patients completed a full-dose chemoradiotherapy as planning. Then 53 and 57 patients received a radical surgery, and 8 and 14 cases were confirmed as ypCR in two groups (P?=?0.157). The other 10 patients failed to receive a definitive resection because of unresectable disease. Similar toxicities were observed between two groups and more incision healing delay were found in Arm B (3 vs.13, P?=?0.011). No statistical differences were observed in local-regional control (P?=?0.856), disease-free survival (P?=?0.349) and overall survival (P?=?0.553). Mesorectal fascia (MRF) involvement was an independent prognostic factor for survival in multivariate analysis. CONCLUSIONS:A concomitant boost to oxalipatin-combined preoperative chemoradiotherapy demonstrated a slightly higher pCR rate but delayed incision healing after surgery. The impact of MRF involvement on survival merits further investigations. TRIAL REGISTRATION:NCT01064999 (ClinicalTrials.gov).
Project description:Choosing the most effective approach for treating rectal cancer with mesorectal fascia (MRF) involvement or closeness and synchronous distant metastases is a current clinical challenge. The aim of this retrospective study was to determine if upfront systemic chemotherapy and short-course radiotherapy (RT) with delayed surgery enables R0 resection.Between March 2009 and October 2009, six patients were selected for upfront chemotherapy and short-course RT (5 × 5 Gy) with delayed surgery. The patients had locally advanced primary tumors with MRF involvement or closeness, as well as synchronous and potentially resectable distant metastases. Chemotherapy was administered to five patients between the end of the RT and surgery. All patients underwent total mesorectal excision (TME).The median patient age was 54 years (range 39-63). All primary and metastatic lesions were resected simultaneously. The median duration between short-course RT and surgery was 13 weeks (range, 7-18). R0 resection of rectal lesions was achieved in 5 patients. One patient, who had a very low-lying tumor, had an R1 resection. The median follow-up duration for all patients was 16.7 months (range, 15.5-23.5). One patient developed liver metastasis at 15.7 months. There have been no local recurrences or deaths.Upfront chemotherapy and short course RT with delayed surgery is a valuable alternative treatment approach for patients with MRF involvement or closeness of rectal cancer with distant metastases.
Project description:There still is no evidence which neoadjuvant therapy regimen for stage II-III rectal cancer is superior. The aim of this study was to compare results achieved after long-course chemoradiotherapy (CRT) with short-term radiotherapy (RT) followed by delayed surgery.A randomized trial was carried out between 2007-2013. One hundred fifty patients diagnosed with stage II-III rectal cancer were randomized into one of two neoadjuvant treatment arms: conventional chemoradiotherapy (CRT) and short-term radiotherapy (RT) followed by surgery after 6-8 weeks. Primary endpoints of this trial were downstaging and pathological complete response rate. Secondary endpoints were local recurrence rate and overall survival.The pathological complete response was found in 3 (4.4%) cases after RT and 8 (11.1%) after CRT (P?=?0.112). Downstaging (stage 0 and I) was observed in 21 (30.9%) cases in RT group vs. 27 (37.5%) cases in CRT group (P?=?0.409). Median follow-up time was 39.7 (range 4.9-79.7) months. 3-years overall survival (OS) was 78% in RT group vs. 82.4% in CRT group (P?=?0.145), while disease-free survival (DFS) differed significantly - 59% in RT group vs. 75.1% in CRT group (P?=?0,022). Hazard ratio of cancer progression for RT patients was 1.93 (95% CI: 1.08-3.43) compared to CRT patients.Three-years disease-free survival was better in CRT group comparing with RT group with no difference in overall survival.http://clinicaltrials.gov identifier NCT00597311. January 2008.
Project description:Different neoadjuvant therapy regimens are available for rectal cancer, but the relative effects are controversial. The aim of the present network meta-analysis (NMA) was to estimate the relative efficacy and safety of neoadjuvant therapies for resectable rectal cancer. MEDLINE, EMBASE and Cochrane Central Registry of Controlled Trials were searched for publications dated from 1946 up to June 2018. The present study included randomized clinical trials that compared treatments for resected rectal cancer: Surgery alone, surgery preceded by neoadjuvant radiotherapy (RT), neoadjuvant chemotherapy (CT) or neoadjuvant chemoradiotherapy (CRT). Direct pairwise comparisons and NMA were conducted. A total of 23 randomized controlled trials were included in the present study. RT had an overall survival (OS) benefit when compared with surgery alone [HR (hazard ratio), 0.89; 95% confidence interval (CI), 0.82-0.97; quality of evidence, high]. All three neoadjuvant regimens were associated with lower local recurrence (LR) when compared with surgery alone [RT: odds ratio (OR), 0.44; 95% CI, 0.35-0.65; quality of evidence, high; CRT: OR, 0.34; 95% CI, 0.23-0.56; quality of evidence, low and CT: OR, 0.32; 95% CI, 0.11-1.00; quality of evidence, low]. There were no significant differences in OS and LR between CRT and RT (OS: OR, 1.10); 95% CI, 0.93-1.20; LR: OR, 0.81; 95% CI, 0.61-1.10). Ranking probabilities indicated that CRT was the best strategy for local control, with a surface under the cumulative ranking curve (SUCRA) of 78.78%. Patients treated with RT had improved disease-free survival compared with those treated with surgery alone (HR, 0.82; 95% CI, 0.64-1.00; quality of evidence, low). Neoadjuvant RT or CRT did not significantly improve distant metastases compared with surgery alone (RT: OR, 0.87; 95% CI, 0.69-1.10 and CRT: OR, 0.75; 95% CI, 0.47-1.10). CRT had an improved pathological complete response rate compared with RT (OR, 4.90; 95% CI, 21.80-17.00; quality of evidence, low). No significant difference for the risk of anastomotic leak between each treatment was observed in the NMA. In conclusion, RT decreased the LR and improved OS compared with surgery alone for resected rectal cancer. CRT was the best neoadjuvant therapy analyzed and CT was likely the second best for all outcomes based on SUCRA. However, these findings were limited by overall low quality of evidence.
Project description:The management of rectal cancer has evolved significantly in the last few decades. Significant improvements in local disease control were achieved in the 1990s, with the introduction of total mesorectal excision and neoadjuvant radiotherapy. Level 1 evidence has shown that, with neoadjuvant chemoradiation therapy (CRT) the rates of local recurrence can be lower than 6% and, as a result, neoadjuvant CRT currently represents the accepted standard of care. This approach has led to reliable tumor down-staging, with 15-27% patients with a pathological complete response (pCR)-defined as no residual cancer found on histological examination of the specimen. Patients who achieve pCR after CRT have better long-term outcomes, less risk of developing local or distal recurrence and improved survival. For all these reasons, sphincter-preserving procedures or organ-preserving options have been suggested, such as local excision of residual tumor or the omission of surgery altogether. Although local recurrence rate has been stable at 5-6% with this multidisciplinary management method, distal recurrence rates for locally-advanced rectal cancers remain in excess of 25% and represent the main cause of death in these patients. For this reason, more recent trials have been looking at the administration of full-dose systemic chemotherapy in the neoadjuvant setting (in order to offer early treatment of disseminated micrometastases, thus improving control of systemic disease) and selective use of radiotherapy only in non-responders or for low rectal tumors smaller than 5?cm.
Project description:BACKGROUND:Neoadjuvant therapy improves survival of patients with clinical stage II and III rectal cancer in clinical trials. In this study, we investigated the administration of neoadjuvant radiotherapy (neo-RT) and neoadjuvant chemoradiotherapy (neo-CRT) and its association with survival in resected patients in 2 European countries (The Netherlands and Sweden) and at 3 specialist centers. MATERIALS AND METHODS:Administration of neoadjuvant treatment (all registries) and overall survival after surgery in The Netherlands and Sweden were assessed. Hazard ratios (HRs) were obtained using Cox regression adjusted for potential confounders. RESULTS:A total of 16,095 rectal cancer patients with clinical stage II and III were eligible for analyses. Large variations in administration of neo-RT and neo-CRT were observed. Elderly patients less often received neo-RT and neo-CRT. Patients with stage III disease received neo-CRT more frequently than neo-RT. Administration of neo-RT versus surgery without neoadjuvant treatment was significantly associated with improved survival in The Netherlands (HR, 0.62; 95% confidence interval [CI], 0.53-0.73) as well as in Sweden (HR, 0.79; 95% CI, 0.69-0.90). Administration of neo-CRT was associated with enhanced survival in The Netherlands (HR, 0.62; 95% CI, 0.50-0.78) but not in Sweden (HR, 0.97; 95% CI, 0.80-1.18). The mortality of patients treated with neo-CRT compared with neo-RT showed inconsistent results in population-based centers. CONCLUSIONS:Our results support an association of neo-RT with enhanced survival among stage II and III rectal cancer patients. Comparing neo-CRT with neo-RT, larger variations and inconsistent results with respect to survival were observed across centers.
Project description:Background:To retrospectively evaluate the difference in terms of pathologic complete response (pCR) according to time elapsed between chemoradiation (CRT) and total mesorectal excision (TME) on a large unselected real-life dataset of locally advanced rectal cancer (LARC) patients. Methods:A multicentre retrospective cohort study of LARC patients from 21 Italian Radiotherapy Institutions was performed. Patients were stratified into 3 different time intervals from CRT. The 1st group included 300 patients who underwent TME within 6 weeks, the 2nd 1598 patients (TME within 7-12 weeks) and the 3rd 196 patients (TME within 13 or more weeks after CRT), respectively. Results:Data on 2094 LARC patients treated between 1997 and 2016 were considered suitable for analysis. Overall, 578 patients had stage II while 1516 had stage III histological proven invasive rectal adenocarcinoma. A CRT schedule of one agent (N = 1585) or 2-drugs (N = 509) was administered. Overall, pCR was 22.3% (N = 468 patients). The proportion of patients achieving pCR with respect to time interval was, as follows: 12.6% (1st group), 23% (2nd group) and 31.1% (3rd group) (p < 0.001), respectively. The pCR relative risk comparison of 2nd to 1st group was 1.8, while 3rd to 2nd group was 1.3. Moreover, between the 3rd and 1st group, a pCR relative risk of 2.4 (p < 0.01) was noted. At univariate analysis, clinical stage III (p < 0.001), radiotherapy dose >5040 cGy (p = 0.002) and longer interval (p < 0.001) were significantly correlated to pCR. The positive impact of interval (p < 0.001) was confirmed at multivariate analysis as the only correlated factor. Conclusion:We confirmed on a population-level that lengthening the interval (>13 weeks) from CRT to surgery improves the pathological response (pCR and pathologic partial response; pPR) in comparison to historic data. Furthermore, radiotherapy dose >5040 cGy and two drugs chemotherapy correlated with pPR rate.
Project description: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.