An interventional study of Maastro applicator in Rectal Cancer, Feasibility and Toxicity, sponsored by Maastricht Radiation Oncology. Active, not recruiting at 1 site in Netherlands. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-08-14.
Sponsored by Maastricht Radiation Oncology · Not applicable, Interventional, and Treatment
The goal of this interventional pilot trial is to confirm that Maastro endoluminal HDR ( High Dose Radiation) contact brachytherapy boosting is feasible and may increase the chance of functional organ sparing of the rectum in patients with rectal cancer. Participants will be treated with chemoradiotherapy and an endoluminal boost with the Maastro applicator.
The goal of this clinical trial is to confirm that Maastro endoluminal HDR contact brachytherapy boosting is feasible and may increase the chance of functional organ sparing of the rectum in patients with rectal cancer. If at least 7 out of 10 planned Maastro applicator treatment series (3 fractions per series) can be conducted successfully from a procedural point of view the treatment will be considered feasible. The study intervention will be similar to the study treatment of arm B of the OPERA trial. Opposed to the treatment in arm B of the OPERA trial, the endoluminal boost will be given using HDR brachytherapy with the Maastro applicator instead of a CXRT (Contact X-ray Radiotherapy) device. The dose profile of the Maastro applicator is similar to the dose profile of CXRT device. As in the OPERA trial patients will be stratified based on tumor size. As the diameter of the treatment field of the largest Maastro applicator (there are two sizes) equals 2.5 cm we will stratify for tumor diameter \< 2.5 cm v ≥ 2.5 cm. In the OPERA trial patients were stratified for a tumor diameter of \< 3.0 cm v ≥ 3.0 cm as currently the largest applicator diameter for the CXRT device is 3.0 cm (currently available applicators: 2.0, 2.5 and 3.0 cm). The endoluminal boost will consist of 3 fractions with a dose equivalent to 30 Gy per fraction prescribed at the surface of the applicator. The 3 boost fractions will be delivered over a 4-week time period (week 1-2-4). Conform OPERA protocol, patients with a tumor size \< 2.5 cm will receive an upfront endoluminal HDR contact boost followed by concurrent chemoradiotherapy (25x1.8 Gy combined with capecitabine 825 mg/m2 bd on radiotherapy days). Patients with a tumor size ≥ 2.5 cm will first undergo concurrent chemoradiotherapy (25x1.8 Gy combined with capecitabine 825 mg/m2 bd on radiotherapy days) to first shrink the tumor and will receive the endoluminal HDR contact boost afterwards in order to eventually fit the tumor surface in the surface of the Maastro applicator.
2,400 studies on the registry are indexed under Rectal Neoplasms; 587 are open to participants now.
This study's planned enrollment of 10 is below the median of 65 across 1,751 interventional studies indexed under Rectal Neoplasms.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adjuvant and neoadjuvant
Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The intervention is similar to the treatment of arm B of the published OPERA trial, however the endoluminal boost will be given using the Maastro applicator instead of a CXRT device.
Device: Maastro applicator
The dose profile of the Maastro applicator is similar to the dose profile of a CXRT device. Patients will be stratified based on tumor size. The cut-off is set at the maximum diameter of the treatment surface of the Maastro applicator. The boost consists of 3 fractions with a dose equivalent to 30 Gy per fraction prescribed at the surface of the applicator. The 3 boost fractions will be delivered over a 4-week time period. Patients with a tumor size \< 2.5 cm will receive an upfront boost followed by concurrent chemoradiotherapy (25x1.8 Gy combined with capecitabine 825 mg/m2 bd on radiotherapy days). Patients with a tumor size ≥ 2.5cm will first undergo concurrent chemoradiotherapy (25x1.8 Gy combined with capecitabine 825 mg/m2 bd on radiotherapy days) and will afterwards receive the boost.
Clinical feasibility of the Maastro boosting technique.
If at least 7 out of 10 planned Maastro applicator treatment series (3 fractions per series) can be conducted successfully from a procedural point of view the treatment will be considered feasible.
Time frame: During treatment
Efficacy of Maastro applicator endoluminal HDR contact brachytherapy boosting in functional organ sparing of the rectum
Percentage of patients with a persistent clinical complete response with good rectal function (no irreversible G2 or higher toxicity that does not respond to treatment) at 3 years. (number of patients with a complete response AND no persistent G2 or higher rectal toxicity) / (total number of patients) \* 100%
Time frame: 3 years follow-up
Percentage of planned interventional Maastro procedures that could be conducted successfully from a procedural point of view.
(procedures conducted successfully from a procedural point of view according to the checklist, please refer to appendix A) / (total number of procedures) \* 100%
Time frame: During treatment
Duration of the application procedure.
Time from insertion of the proctoscope to finalising removal of the proctoscope in minutes.
Time frame: During treatment
Percentage of patients with G3 or higher rectal toxicity up to 3 months after treatment potentially attributable to endoluminal HDR contact brachytherapy.
Doctor reported CTCEA (Common Terminology Criteria for Adverse Events) v. 5 G3 or higher rectal toxicity not present before the start of treatment and occurring up to 3 months after treatment potentially attributable to endoluminal radiotherapy. (number of patients with new G3 or higher rectal toxicity up to 3 months after treatment) / (total number of patients) \* 100%
Time frame: 3 months follow-up
Clinical complete response rate up to 3 years after treatment.
Clinical response will be assessed using the "watch and wait" protocol which is part of standard clinical care at MUMC+ ( Maastricht Medical University Center). Data will be reported at 3 months, 6 months, 1 year, 2 years and 3 years of follow-up. (number of patients with a cCR) / (total number of patients) \* 100%
Time frame: 3 years follow-up
Rectal toxicity scored according to CTCAE v. 5 up to 3 years after treatment.
Both patient and doctor reported rectal toxicity scored according to CTCEA v. 5 will be determined before each application procedure, weekly during chemoradiotherapy, 1 week after treatment and 1, 3, 6, 12, 18, 24 and 36 months after treatment.
Time frame: 3 years follow-up
Genitourinary toxicity scored according CTCAE v. 5 up to 3 years after treatment.
Both patient and doctor reported genitourinary toxicity scored according to CTCEA v. 5 will be determined before each application procedure, weekly during chemoradiotherapy, 1 week after treatment and 1, 3, 6, 12, 18, 24 and 36 months after treatment.
Time frame: 3 years follow-up
Health status and quality of life as measured by QLQ (quality of life questionnaire)-C30 up to 3 years after treatment.
Patients will fill out the validated health status and quality of life questionnaire QLQ-C30 after inclusion (at baseline) and 1, 3, 6, 12, 18, 24 and 36 months after treatment.
Time frame: 3 years follow-up
Health status and quality of life as measured by QLQ-CR29 (Colo Rectal) up to 3 years after treatment.
Patients will fill out the validated health status and quality of life questionnaire QLQ-CR29 after inclusion (at baseline) and 1, 3, 6, 12, 18, 24 and 36 months after treatment.
Time frame: 3 years follow-up
Health status and quality of life as measured by EQ-5D (EuroQol Five Dimensions Health Questionnaire) up to 3 years after treatment.
Patients will fill out the EQ-5D-5L after inclusion (at baseline) and 1, 3, 6, 12, 18, 24 and 36 months after treatment.
Time frame: 3 years follow-up
Long-term rectal functional outcome as measured by LARS 9 Low Anterior Resection Syndrome) score up to 3 years after treatment.
Patients will fill out the LARS questionnaire after inclusion (at baseline) and 1, 3, 6, 12, 18, 24 and 36 months after treatment.
Time frame: 3 years follow-up
Local recurrence rate up to 5 years after treatment.
Local recurrence rate is defined as the rate of rectal recurrences at the site of the initial primary tumor. Local recurrence rate will be registered up to 5 years after treatment by consulting the hospital patient file. (number of patients with a local recurrence) / (total number of patients) \* 100%
Time frame: 5 years follow-up
Locoregional recurrence rate up to 5 years after treatment.
Locoregional recurrence rate is defined as the rate of recurrences in the rectum and the regional pelvic lymph node areas. Locoregional recurrence rate will be registered up to 5 years after treatment by consulting the hospital patient file. (number of patients with a locoregional recurrence) / (total number of patients) \* 100%
Time frame: 5 years follow-up
Metastatic rate up to 5 years after treatment.
Metastatic rate is defined as the rate of distant metastasis. Metastatic rate will be registered up to 5 years after treatment by consulting the hospital patient file. (number of patients with distant metastases) / (total number of patients) \* 100%
Time frame: 5 years follow-up
Salvage surgery rate after treatment.
The percentage of patients undergoing salvage surgery will be determined. Both TME and local excision rate will be reported separately and combined. The reason for surgery (e.g. local recurrence, patient's wish, unacceptable toxicity) if available and the pathologic outcome (e.g. pCR) will also be reported for patients undergoing surgery. Salvage surgery rate will be registered up to 5 years after treatment by consulting the hospital patient file. (number of patients undergoing salvage surgery) / (total number of patients) \* 100%
Time frame: 5 years follow-up
Overall and disease specific survival rate up to 5 year after treatment.
Both overall survival rate and disease specific survival rates will be reported. Survival rate will be registered up to 5 years after treatment by consulting the hospital patient file. 100% - (number of patients having died within 5 years after treatment \[due to any causes or due to rectal cancer\] / total number of patients \* 100%)
Time frame: 5 years follow-up
The diagnostic value of clinical response assessment using digital rectal examination, endoscopy and MRI after endoluminal radiation boosting using the Maastro applicator.
Clinical response will be assessed using the "watch and wait" protocol which is part of standard clinical care at MUMC+. According to this protocol tumor response is assessed using a digital rectal examination, sigmoidoscopy and MRI (including T2 and DWI). This combined modality approach has been reported to have a specificity of 97% and a sensitivity of 71% for the detection of complete tumor response after neoadjuvant (chemo)radiotherapy. The exact diagnostic value of this multimodality approach has not been validated in the setting of an endoluminal boost with the Maastro applicator. We will evaluate the diagnostic value by relating the test results to a persistent clinical complete response at 1 and 2 years, residual tumor (yes/no) in the resection specimen in case of salvage surgery and a clinical local recurrence in case of refusal of salvage surgery.
Time frame: during follow-up
Complications within the first 30 days after completion of salvage total mesorectal excision (TME) surgery up to 3 years after treatment.
Complications within the first 30 days after completion or salvage TME surgery will be scored according to the classification of surgical complications by Clavien-Dindo (16). Complications will be registered up to 3 years after treatment by consulting the hospital patient file.
Time frame: 3 years follow-up
Collecting 3D ultrasound measurements of the gross tumor volume (GTV) and intestinal wall layers at every fraction of Maastro applicator brachytherapy.
These images can later be used for scientific research including (but not limited to): * Developing a method for ultrasound guided GTV / organs at risk (OAR) (various intestinal wall layers, neighboring organs) dose reconstruction calculation in rectal cancer. This information is crucial in order to establish adequate dose-response relations for tumor control (Tumor Control Probability; TCP) and normal tissue toxicity (Normal Tissue Complication Probability, NTCP). Insight in the dose-response relations will allow the clinician to understand in which way the treatment to the individual patient should be adapted to increase cure rates and/or minimise additional toxicity. * Developing ultrasound guided treatment planning software (TPS) which allows future individualised treatment planning.
Time frame: During treatment
Plan to share: No
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