CAPIRI-IMRT: a phase II study of concurrent capecitabine and irinotecan with intensity-modulated radiation therapy for the treatment of recurrent rectal cancer

Multidisciplinary management of locally recurrent rectal cancer with carbon ion radiotherapy followed by prophylactic removal of the irradiated bowel: a case report

BACKGROUND

Locally recurrent rectal cancer (LRRC) involving the upper sacrum is typically incurable, and palliative treatment is the only option for most patients, resulting in a poor prognosis and reduced quality of life. Carbon ion radiotherapy (CIRT) has emerged as a promising modality for treating LRRC. This report presents a case of LRRC with sacral involvement that was managed via multidisciplinary therapy incorporating CIRT.

CASE PRESENTATION

A 55-year-old male was diagnosed with an anastomotic recurrence of rectal cancer 15 months after undergoing anterior resection. Computed tomography (CT) suggested that the lesion was at an anastomosis site and broadly adherent to the upper sacrum, and colonoscopy confirmed the diagnosis of LRRC. Histopathological examination of the biopsy specimens revealed adenocarcinoma cells and that lesion was genetically RAS-wild. Induction chemotherapy with mFOLFOX6 and panitumumab was used as the first treatment. The recurrent lesion shrank and no signs of distant metastasis were observed after 11 cycles, although the range of the lesions attached to the sacrum remained unchanged. Therefore, we provided CIRT for this inoperable lesion and prophylactically removed the radiation-exposed bowel including the recurrent lesion, because radiation-induced ulcers can cause bleeding and perforation. Despite the presence of considerable fibrosis in the irradiated region, the operation was successful and the postoperative course had no untoward incidents. He is still recurrence-free 24 months following surgery, despite the lack of adjuvant chemotherapy. This is the first report of CIRT followed by CIRT-irradiated bowel removal for an unresectable anastomosis recurrent lesion.

CONCLUSIONS

The clinical course of this case suggests that CIRT could be a potentially effective therapeutic option for LRRC involving the bowel, as long as the prophylactic removal of the irradiated bowel is performed at the optimal time. Further research involving larger sample sizes is warranted to validate the findings and conclusions of this case report.

TORCH-R trial protocol: hypofractionated radiotherapy combined with chemotherapy and toripalimab for locally recurrent rectal cancer: a prospective, single-arm, two-cohort, phase II trial

For patients with locally recurrent rectal cancer (LRRC), the response rate to chemoradiotherapy is 40%-50%. Additionally, only approximately 40%-50% of patients with recurrent rectal cancer are able to undergo R0 resection. Recent studies in locally advanced rectal cancer (LARC) have shown promising synergistic effects when combining immunotherapy (PD-1/PD-L1 antibodies) with neoadjuvant chemoradiotherapy (nCRT). Therefore, incorporating immunotherapy into the treatment regimen for LRRC patients has the potential to further improve response rates and prognosis. To investigate this, the TORCH-R trial was conducted. This prospective, single-arm, two-cohort, phase II trial focuses on the use of hypofractionated radiotherapy, chemotherapy, and immunotherapy in LRRC patients without or with oligometastases. The trial will include two cohorts: cohort A consists of rectal cancer patients who are treatment-naive for local recurrence, and cohort B includes patients with progressive disease after first-line chemotherapy. Cohort A and cohort B patients will receive 25-40 Gy/5 Fx irradiation or 15-30 Gy/5 Fx reirradiation for pelvic recurrence, respectively. Subsequently, they will undergo 18 weeks of chemotherapy, toripalimab, and stereotactic ablative radiotherapy (SABR) for all metastatic lesions between chemoimmunotherapy cycles. Decisions regarding follow-up of complete response (CR), radical surgery, sustained treatment of non-resection, or exiting the trial are made by a multidisciplinary team (MDT). The primary endpoint of this study is the local objective response rate (ORR). The secondary endpoints include the extrapelvic response rate, duration of response, local recurrence R0 resection rate, progression-free survival (PFS), overall survival (OS), and safety and tolerability. Notably, this trial represents the first clinical exploration of inducing hypofractionated radiotherapy, chemotherapy, and immunotherapy in LRRC patients.

Clinical trial registration

https://clinicaltrials.gov/study/NCT05628038, identifier NCT05628038.

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.

Outcomes and Prognostic Factors for Locally Recurrent Rectal Cancer Treated With Proton Beam Therapy

Purpose

Our objective was to report the outcome and prognostic factors for patients with locally recurrent rectal cancer (LRRC) treated with proton beam therapy (PBT) at our institution.

Methods and Materials

The study included PBT-treated patients with LRRC between December 2008 and December 2019. Treatment response was stratified using an initial imaging test after PBT. Overall survival (OS), progression-free survival (PFS), and local control (LC) were estimated using the Kaplan-Meier method. Each outcome's prognostic factors were verified using the Cox proportional hazards model.

Results

Twenty-three patients were enrolled (median follow-up, 37.4 months). There were 11 patients with complete response (CR) or complete metabolic response (CMR), 8 with partial response or partial metabolic response, 2 with stable disease or stable metabolic response, and 2 with progressive disease or progressive metabolic disease. Three- and 5-year OS, PFS, and LC were 72.1% and 44.6%, 37.9% and 37.9%, and 55.0% and 47.2%, respectively, with 54.4 months' median survival time. The maximum standardized uptake value of fluorine-18-fluorodeoxyglucose-positron emission tomography-computed tomography (¹⁸F-FDG-PET/CT) before PBT (cutoff value, 10) showed significant differences in OS (P = .03), PFS (P = .027), and LC (P = .012). The patients who achieved CR or CMR after PBT had significantly better LC than those with non-CR or non-CMR (hazard ratio, 4.49; 95% confidence interval, 1.14-17.63; P = .021). Older patients (aged ≥65 years) had significantly higher LC and PFS rates. Patients with pain before PBT and larger tumors (≥30 mm) also had significantly lower PFS. Of 23 patients, 12 (52%) experienced further local recurrence after PBT. One patient developed grade 2 acute radiation dermatitis. Regarding late toxicity, grade 4 late gastrointestinal toxic effects were recorded in 3 patients, in 2 of whom reirradiation was associated with further local recurrence after PBT.

Conclusions

The results showed that PBT may have potential to be a good treatment option for LRRC. ¹⁸F-FDG-PET/CT before and after PBT may be useful for assessing tumor response and predicting outcomes.

Comparison of dosimetries of carbon-ion pencil beam scanning, proton pencil beam scanning and volumetric modulated arc therapy for locally recurrent rectal cancer

We compared the dose distributions of carbon-ion pencil beam scanning (C-PBS), proton pencil beam scanning (P-PBS) and Volumetric Modulated Arc Therapy (VMAT) for locally recurrent rectal cancer. The C-PBS treatment planning computed tomography (CT) data sets of 10 locally recurrent rectal cancer cases were randomly selected. Three treatment plans were created using identical prescribed doses. The beam angles for C-PBS and P-PBS were identical. Dosimetry, including the dose received by 95% of the planning target volume (PTV) (D95%), dose to the 2 cc receiving the maximum dose (D2cc), organ at risk (OAR) volume receiving > 15Gy (V15) and > 30Gy (V30), was evaluated. Statistical significance was assessed using the Wilcoxon signed-rank test. Mean PTV-D95% values were > 95% of the volume for P-PBS and C-PBS, whereas that for VMAT was 94.3%. However, PTV-D95% values in P-PBS and VMAT were < 95% in five and two cases, respectively, due to the OAR dose reduction. V30 and V15 to the rectum/intestine for C-PBS (V30 = 4.2 ± 3.2 cc, V15 = 13.8 ± 10.6 cc) and P-PBS (V30 = 7.3 ± 5.6 cc, V15 = 21.3 ± 13.5 cc) were significantly lower than those for VMAT (V30 = 17.1 ± 10.6 cc, V15 = 55.2 ± 28.6 cc). Bladder-V30 values with P-PBS/C-PBS (3.9 ± 4.8 Gy(RBE)/3.0 ± 4.0 Gy(RBE)) were significantly lower than those with VMAT (7.9 ± 8.1 Gy). C-PBS provided superior dose conformation and lower OAR doses compared with P-PBS and VMAT. C-PBS may be the best choice for cases in which VMAT and P-PBS cannot satisfy dose constraints. C-PBS could be another choice for cases in which VMAT and P-PBS cannot satisfy dose constraints, thereby avoiding surgical resection.

Protective ileostomy increased the incidence of rectal stenosis after anterior resection for rectal cancer

BACKGROUND

In most of the views, rectal stenosis after anterior resection for rectal cancer results from pelvic radiotherapy. However, patients without receiving radiotherapy also suffer stenosis. In this study, we evaluated the factors associated with rectal stenosis after anterior rectal resection (ARR).

METHODS

We conducted a retrospective study with ARR patients who underwent neoadjuvant chemoradiotherapy and the patients without radiotherapy. Patients who received watch and wait strategy with a clinical complete response after chemoradiotherapy were also included. Patients with colonoscopy follow-up were included for further analyses; 439 patients who underwent neoadjuvant chemoradiotherapy; 545 patients who received ARR without radiotherapy and 33 patients who received watch and wait strategy. Stenosis was diagnosed when a 12-mm diameter colonoscopy could not be passed through the rectum. Univariate and multivariate logistic regression analyses were performed to identify variables associated with rectal stenosis.

RESULTS

According to the multivariate analysis in patients receiving ARR, both protective stoma and preoperative radiotherapy affected the occurrence of stenosis, with the odds ratios (ORs) of 3.375 and 2.251, respectively. According to the multivariate analysis, a preventive ileostomy was the only factor associated with stenosis both in patients receiving preoperative radiotherapy and without radiotherapy. Non-reversal ileostomy and long time between ileostomy and restoration increased the possibility of stenosis. In 33 patients who received watch and wait strategy, only one patient (3%) experienced stenosis.

CONCLUSION

Both surgery and radiotherapy are risk factors for rectal stenosis in rectal cancer patients. Compared to preoperative radiotherapy, a protective ileostomy is a more critical factor associated with rectal stenosis.

Carbon-ion Radiotherapy for Colorectal Cancer

Heavy-ion radiotherapy (RT) is a kind of particle RT, and carbon-ion beam constitutes the primary delivery method of heavy-ion RT. Unlike the conventional photon modalities, particle RT, in particular carbon-ion radiotherapy (CIRT), offers unique physical and biological advantages. Particle therapy allows for substantial dose delivery to tumors with minimal surrounding tissue damage. In addition, CIRT in particular possesses biological advantages such as inducing increased double-strand breaks in DNA structures, causing irreversible cell damage independently of cell cycle or oxygenation, more so than proton or photon. It can be expected that CIRT is effective on radioresistant cancers such as colorectal cancers (CRCs). We introduced the results of CIRT for local recurrent rectal cancer, lung metastasis, liver metastasis, and lymph node metastasis.

Re-irradiation With Carbon Ion Radiotherapy for Pelvic Rectal Cancer Recurrences in Patients Previously Irradiated to the Pelvis

BACKGROUND/AIM

Re-irradiation of locally recurrent rectal cancer poses challenges due to the proximity of critical organs, such as the bowel. This study aimed at evaluating the safety and efficacy of re-irradiation with Carbon Ion Radiotherapy (CIRT) in rectal cancer patients with local recurrence.

PATIENTS AND METHODS

Between 2014 and 2018, 14 patients were treated at the National Center of Oncological Hadrontherapy (CNAO Foundation) with CIRT for locally recurrent rectal cancer.

RESULTS

All patients concluded the treatment. No G≥3 acute/late reaction nor pelvic infections were observed. The 1-year and 2-year local control rates were, 78% and 52%, respectively, and relapse occurred close to the bowel in 6 patients. The 1-year and 2-year overall survival rates were 100% and 76.2% each; while the 1-year and 2-year metastasis free survival rates were 64.3% and 43%.

CONCLUSION

CIRT as re-irradiation for locally recurrent rectal cancer emerges as a safe and valid treatment with an acceptable rate of morbidity of surrounding healthy tissue.

The role of carbon ion radiotherapy for unresectable locally recurrent rectal cancer: a single institutional experience

Background

Treatment for locally recurrent rectal cancer after surgery is still a challenge. With the physical and biological advantages, carbon-ion radiotherapy (CIRT) could be a choice for these patients. The purpose of this study was to investigate the efficacy and safety of CIRT for unresectable locally recurrent rectal cancer in Chinese patients.

Methods

Date from 25 patients with unresectable locally recurrent rectal cancer treated by CIRT from July 2015 to April 2019 were analyzed retrospectively. The endpoints of this study were overall survival (OS), local control (LC) and acute and late toxicity.

Results

With the median follow-up of 19.6 (range 5.1–52.5) months, data of all 25 patients were collected. Median prescribed dose for tumor was 72Gy (relative biologic efficacy (RBE)) (range 48–75.6Gy (RBE)). The LC rates at 1 and 2 years were 90.4 and 71.8%. Overall LC at 1- and 2-year were 76.2 and 30.5% for 9 patients whose prescribed tumor doses of CIRT< 66 Gy (RBE), 100 and 100% for 16 patients whose prescribed doses of CIRT≥66 Gy (RBE). Patients received ≥66 Gy (RBE) had obviously better LC rates than those received < 66 Gy (RBE) (P = 0.001). The OS rates at 1 and 2 years were 82.9 and 65.1%, respectively. No acute toxicity over grade 2 was observed, grade 3 late toxicity were observed in 3 patients: gastrointestinal toxicity (n = 1), neuropathy (n = 1), pelvic infection (n = 1). No Grade 4 or higher toxicity was observed.

Conclusion

Our study shows that CIRT is effective for unresectable locally recurrent rectal cancer patients with acceptable toxicity.

Prospective Observational Study of High-Dose Carbon-Ion Radiotherapy for Pelvic Recurrence of Rectal Cancer (GUNMA 0801)

Background and purpose: Favorable clinical outcomes of carbon-ion radiotherapy for pelvic recurrence of rectal cancer have been described by previous prospective phase I/II and II studies; however, these studies were performed at a single institution. Therefore, we conducted a prospective observational study aimed at exploring whether carbon-ion radiotherapy for post-operative pelvic recurrence of rectal cancer provides a less invasive local treatment strategy with higher cure rates than other anticancer treatments.

Materials and methods: Patients (1) with pelvic recurrence of rectal cancer, as confirmed by histology or diagnostic imaging; (2) without distant metastasis; (3) who had undergone curative resection of their primary disease and regional lymph nodes, without gross or microscopic residual disease; and (4) with radiographically measurable tumors were included in this study. The total carbon-ion radiotherapy dose for all patients was 73.6 Gy [relative biological effectiveness (RBE)] administered in 16 fractions once daily for 4 days a week (Tuesday to Friday).

Results: A total of 28 patients were enrolled between October 2011 and July 2017. The median follow-up duration was 38.9 months. The 3-year overall survival, local control, and progression-free survival rates were 92, 86, and 31%, respectively. At the time of the analysis, 4 patients had local recurrence, and 7 had died of rectal cancer. None of the patients developed grade 3 or higher acute toxicities. Late toxicities occurred in 2 and 7 patients who developed grade 3 pelvic infection and grade 2 peripheral neuropathy, respectively.

Conclusion: Carbon-ion radiotherapy for pelvic recurrence of rectal cancer showed favorable clinical outcomes and is a highly curative and less invasive local treatment.

Chemoradiotherapy for Local Recurrence of Rectal Cancer: A Single Center Study of 18 Patients

BACKGROUND/AIM

When possible, surgical resection is recommended for local recurrence after resection of colorectal cancer. In unresectable cases, chemotherapy is usually indicated, although the success of chemoradiotherapy (CRT) in this setting is unclear.

PATIENTS AND METHODS

We retrospectively reviewed the treatment outcomes of 18 patients who received CRT for unresectable local recurrence after radical colorectal cancer surgery at our hospital between January 2000 and May 2016.

RESULTS

Of these 18 patients, three experienced complete response and four experienced partial response, resulting in a 39% overall response. With a median follow-up time of 42 months, the 5-year progression-free survival and overall survival were 34.8% and 54.4%, respectively; associated with a median local failure-free survival time of 40.9 months. Two of the three patients that underwent CRT remained local failure free for 5 years.

CONCLUSION

CRT for local recurrence of rectal cancer without distant metastasis produces similar overall survival rates and local control as conventional surgical resection.

Stereotactic Body Radiotherapy for Spinal Metastases: Clinical Experience in 134 Cases From a Single Japanese Institution

OBJECT

This study aimed to clarify the outcomes of stereotactic body radiotherapy for spinal metastases with a uniform dose fractionation schedule in our institution.

MATERIALS AND METHODS

Patients treated with spine stereotactic body radiotherapy were retrospectively reviewed. The prescribed dose was 24 Gy in 2 fractions. End points were local control, pain control, and adverse events. Local control was defined as elimination, shrinkage, or stable disease in the tumor on imaging evaluations. Pain status was measured on a scale of 0 to 10 by patients' self-reports, and pain response was defined as the time at which pain scale score decreased by 2 or more from the baseline score without increase in analgesics. In addition, various treatment- and tumor-specific factors were evaluated to determine predictive values for local and pain control.

RESULTS

This study included 134 lesions in 131 patients, with: lesion histopathology, lung/colorectal/thyroid/renal/breast/prostate/sarcoma/other cancer, 24/22/18/14/12/10/6/25; reirradiation stereotactic body radiotherapy, 82 (61.2%) cases; and postoperative stereotactic body radiotherapy for epidural spinal cord compression, 45 (33.6%) cases. Median follow-up after stereotactic body radiotherapy was 9 months. The 1-year local control rate was 72.3%. Seventy (79.5%) of the 88 cases with pain from spinal metastases achieved pain response. The 1-year pain progression-free rate was 61.7%. Regarding metastases from colorectal cancer, local and pain control rates at 1 year were significantly lower compared with other cancer types (local control rate, 34.1% vs 81.8%; P < .01; pain progression-free rate, 36.9% vs 69.9%; P = .02). On multivariate analysis, colorectal cancer metastases and radiation history were identified as independent predictors of lower local and pain control rates. Radiation-induced myelopathy, radiculopathy, and vertebral compression fractures were observed in 0, 2 (1.5%), and 16 (11.9%) cases, respectively.

CONCLUSIONS

This study showed that spine stereotactic body radiotherapy achieved good local and pain control, with a clinically acceptable safety profile. However, stereotactic body radiotherapy may be less effective against spinal metastases from colorectal cancer.

Acute Toxicity and Tumor Response in Locally Advanced Rectal Cancer After Preoperative Chemoradiation Therapy With Shortening of the Overall Treatment Time Using Intensity-Modulated Radiation Therapy With Simultaneous Integrated Boost: A Phase 2 Trial

BACKGROUND AND PURPOSE

This phase 2 study investigated the efficacy and safety of preoperative intensity modulated radiation therapy with a simultaneous integrated boost (IMRT-SIB) without dose escalation, concomitant with standard capecitabine chemotherapy in locally advanced rectal cancer.

METHODS AND MATERIALS

Between January 2014 and March 2015, 51 patients with operable stage II-III rectal adenocarcinoma received preoperative IMRT with pelvic dose of 41.8 Gy and simultaneously delivered 46.2 Gy to T2/3 and 48.4 Gy to T4 tumor in 22 fractions, concomitant with capecitabine, 825 mg/m²/12 hours, including weekends. The primary endpoint was pathologic complete response (pCR).

RESULTS

Fifty patients completed preoperative treatment according to the protocol, and 47 underwent surgical resection. The sphincter preservation rate for the low rectal tumors was 62%, and the resection margins were free in all but 1 patient. Decrease in tumor and nodal stage was observed in 32 (68%) and 39 (83%) patients, respectively, with pCR achieved in 12 (25.5%) patients. There were only 2 G ≥ 3 acute toxicities, with infectious enterocolitis in 1 patient and dermatitis over the sacral area caused by the bolus effect of the treatment table in the second patient.

CONCLUSIONS

Preoperative IMRT-SIB without dose escalation is well tolerated, with a low acute toxicity profile, and can achieve a high rate of pCR and downstaging.

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.

Carbon-Ion Radiation Therapy for Pelvic Recurrence of Rectal Cancer

PURPOSE

Investigation of the treatment potential of carbon-ion radiation therapy in pelvic recurrence of rectal cancer.

METHODS AND MATERIALS

A phase 1/2 dose escalation study was performed. One hundred eighty patients (186 lesions) with locally recurrent rectal cancer were treated with carbon-ion radiation therapy (CIRT) (phase 1/2: 37 and 143 patients, respectively). The relapse locations were 71 in the presacral region, 82 in the pelvic sidewalls, 28 in the perineum, and 5 near the colorectal anastomosis. A 16-fraction in 4 weeks dose regimen was used, with total dose ranging from 67.2 to 73.6 Gy(RBE); RBE-weighted absorbed dose: 4.2 to 4.6 Gy(RBE)/fraction.

RESULTS

During phase 1, the highest total dose, 73.6 Gy(RBE), resulted in no grade >3 acute reactions in the 13 patients treated at that dose. Dose escalation was halted at this level, and this dose was used for phase 2, with no other grade >3 acute reactions observed. At 5 years, the local control and survival rates at 73.6 Gy(RBE) were 88% (95% confidence interval [CI], 80%-93%) and 59% (95% CI, 50%-68%), respectively.

CONCLUSION

Carbon-ion radiation therapy may be a safe and effective treatment option for locally recurrent rectal cancer and may serve as an alternative to surgery.