For part I population-based data from the national cancer registries of Belgium, the Netherlands, Norway, and Sweden was used. In all countries, the use of chemotherapy increased with stage and... Show moreFor part I population-based data from the national cancer registries of Belgium, the Netherlands, Norway, and Sweden was used. In all countries, the use of chemotherapy increased with stage and decreased with age. Also, 30-day and one-year excess mortality decreased over the years for colon and rectal cancer. After surviving the first postoperative year, the survival of surgically treated older patients aligned with their younger counterparts, except for patients with stage III disease. Part II describes the results of the analyses of the RAPIDO trial. DRTF decreased from 30% in the standard-care group to 24% in the experimental group at 3 years after randomisation, mainly due to a decrease in DM, which is probably due to better compliance preoperatively and perhaps due the earlier treatment of micrometastases in the treatment process. Although patients with DM in the experimental group had worse survival compared to patients in the standard-care group, the cumulative probability of overall survival remained comparable for both treatment groups. If the patients with a complete response can be identified during reassessment after neoadjuvant therapy, surgery may be omitted, a W&W after a cCR with an appropriate follow-up has no additional oncological risk in young patients compared to older patients (part III). This opens the door for potential organ preservation. Show less
During recent decades, many studies have been performed in patients with early glottic cancer, which provide new insight into the two main treatment modalities, TOLMS and radiotherapy, and their... Show moreDuring recent decades, many studies have been performed in patients with early glottic cancer, which provide new insight into the two main treatment modalities, TOLMS and radiotherapy, and their outcomes. The aim of this thesis was: (i) What is the role of TOLMS in T2 glottic carcinoma in the Netherlands? (ii) Should more patients with T2 glottic carcinoma be treated with TOLMS? Within this thesis, we found that (i) the laryngeal preservation rate for T2 glottic carcinoma is higher after primary treatment with TOLMS than after primary treatment with radiotherapy; (ii) that the binary use (yes/no) for the involvement of the anterior commissure (AC) as a prognostic factor leads to inconsistent results, whereas studies with a more detailed classification of the AC show that there is a significant impact on oncological outcomes; (iii) that vertical involvement of the AC on imaging has a significant impact on local control not only in patients treated with TOLMS but also in patients receiving primary radiotherapy; and (iv) that patient with T2 glottic carcinoma treated with radiotherapy reported good long-term functional outcomes, although patients with tumors infiltrating the vocal fold muscle show a trend toward a higher degree of voice handicap than patients with tumor with only superficial spread. Show less
Adapting a radiotherapy treatment plan to the daily anatomy is a crucial task to ensure adequate irradiation of the target without unnecessary exposure of healthy tissue.This adaptation can be... Show moreAdapting a radiotherapy treatment plan to the daily anatomy is a crucial task to ensure adequate irradiation of the target without unnecessary exposure of healthy tissue.This adaptation can be performed by automatically generating contours of the daily anatomy together with fast re-optimization of the treatment plan. These measurescan compensate for the daily variation and ensure the delivery of the prescribed dose distribution at small margins and high robustness settings. In this thesis, we focused on developing a deep learning-based methodology for automatic contouring for real-time adaptive radiotherapy either guided by CT or MR imaging modalities Show less
The studies in this thesis contribute to more accurate risk assessment and prognosis prediction for DCIS and to better response evaluation of IBC treatment.For the Ductal Carcinoma In Situ (DCIS)... Show moreThe studies in this thesis contribute to more accurate risk assessment and prognosis prediction for DCIS and to better response evaluation of IBC treatment.For the Ductal Carcinoma In Situ (DCIS) studies, unbiased cohorts were used within the international Grand Challenge PRECISION consortium, funded by Cancer Research UK and KWF Dutch Cancer Society. DCIS is graded as low-, intermediate-, or high-grade depending on how abnormal the DCIS-cells look like. However, we showed that pathologists often disagree on grade. To overcome this limitation, we found that almost all DCIS scored as non-high-grade by the majority of pathologists express the estrogen receptor (ER) and are negative for the growth factor receptor HER2, whereas high-grade DCIS is mixed in expression for ER and HER2. We also provided insights in the recurrence risks of DCIS after treatment. See also https://cancergrandchallenges.org/teams/precision.The studies on Invasive Breast Cancer (IBC) were performed on a hospital-based cohort. We found for example substantial variation in tumour response evaluation for HER2-positive IBC after pre-operative chemotherapy due to different guidelines used. For accurate outcome analysis, reducing such variation is mandatory. Therefore, we are working on reaching international consensus of response evaluation. Show less
The recent FLAME trial has demonstrated improved local control of intermediate to high-risk prostate cancer after focal dose escalation of the visible tumor. To visualize the tumor, MRI... Show moreThe recent FLAME trial has demonstrated improved local control of intermediate to high-risk prostate cancer after focal dose escalation of the visible tumor. To visualize the tumor, MRI examinations were taken in which prostate tissue characteristics were visualized. Since this treatment strategy improves the clinical outcome of the patient, a technical analysis of the FLAME dataset is useful for the further optimization of focal dose escalation strategies.Delineation of the prostate tumor appeared to be performed differently in the participating radiotherapy departments. Considering the impact on the realized tumor dose, this analysis demonstrated the need for guidelines of tumor delineation on MRI. Due to the complex nature of the treatment plans, in addition a prediction model was developed, which identified patients for which a higher tumor dose could be planned.The application of MRI was also investigated for ‘dose painting by numbers’, in which MRI values are translated to prescription dose without interference of manual tumor delineations. Dose prescription based on MRI appeared robust to daily patient variations, a prerequisite for further development of ‘dose painting by numbers’. However, because of the absence of significant tumor changes during the treatment course, MRI was considered not suitable for early adaptive treatment. Show less
This thesis sought to obtain a better understanding of the composition of the immune microenvironment in NSCLC and how to modulate this tumor immune microenvironment by RT to induce amplified... Show moreThis thesis sought to obtain a better understanding of the composition of the immune microenvironment in NSCLC and how to modulate this tumor immune microenvironment by RT to induce amplified antitumor immune responses to ICIs in advanced NSCLC patients. In the first part of this thesis, a multiangular approach of a combination of protein and mRNA expression with clinicopathological characteristics in a large cohort of early stage, resected NSCLC samples will be discussed. The second part focusses on the immune modulating effects of RT, in particular when combined with immunotherapy treatment in metastatic NSCLC. Show less
Radiotherapy treatments need adequate quality control (QC) to ensure a correct delivery of the prescribed dose to the target area. One of the most extended safety nets for treatments in... Show moreRadiotherapy treatments need adequate quality control (QC) to ensure a correct delivery of the prescribed dose to the target area. One of the most extended safety nets for treatments in conventional radiotherapy machines is in-vivo EPID dosimetry, which uses the dose acquired by an Electronic Portal Imaging Device (EPID) during treatment to accurately reconstruct the dose as it was delivered to the patient.We developed a method to validate radiotherapy treatments delivered on a novel system: the Unity MR-Linac. This machine, which combines a radiation source (linac) and an imaging device (MRI), will help to irradiate tumors more accurately by means of a new range of techniques only available thanks to the image guidance of the MRI during irradiation. The verification of such treatments can be performed by using images of the delivered beam captured by an EPID situated opposite to the radiation source, behind the cryostat of the MRI scanner. This project focuses on the adaptation of an already existing algorithm used with conventional linacs to the new physics and design characteristics of the Unity MR-linac. The main challenge for this adaptation is the presence of the MRI scanner between the patient and the EPID, acting as a secondary source of scatter and as an attenuation medium for the beam. Show less
Prostate cancer (PCa) is frequently treated with radiotherapy. However, depending on the aggressiveness of the disease, the risk of recurrence can be up to 35% within five years of the initial... Show moreProstate cancer (PCa) is frequently treated with radiotherapy. However, depending on the aggressiveness of the disease, the risk of recurrence can be up to 35% within five years of the initial treatment. Patients with localised recurrent PCa are candidates for curative (i.e. salvage) treatment. To overcome the toxicity associated with whole-gland approaches, focal salvage treatments target the index lesion while sparing the surrounding tissue. The studies described in this thesis elaborate on the use of quantitative multi-parametric MRI (mp-MRI) for the detection and localisation of locally recurrent PCa after radiotherapy. Pre-treatment radiomic imaging features were found to have potential to improve recurrence-risk prediction models for high-risk PCa patients treated with radiotherapy. In this thesis, the mp-MRI properties of irradiated benign tissue and recurrent tumour were characterised, with access to pathological samples. These findings can be used as a foundation to establish guidelines (which are currently absent) on how to assess and score MRI scans after radiotherapy. Improving radiological knowledge in the recurrent setting can lead to improved staging and result in better patient selection for salvage treatments. Lastly, this thesis provides evidence on how best to define the region to target, leading to a refinement of focal salvage strategies. Show less
Bone metastases of the long bones can cause pain and pathologic fractures. Local treatment consists of radiotherapy or surgical stabilisation. The most appropriate treatment depends on many factors... Show moreBone metastases of the long bones can cause pain and pathologic fractures. Local treatment consists of radiotherapy or surgical stabilisation. The most appropriate treatment depends on many factors, including the symptoms, the location and extent of the lesion, the wishes and expectations of the patient, and the expected remaining survival. Survival estimation of patients with symptomatic long bone metastases is crucial to prevent over- and undertreatment. This thesis aimed to develop a prognostic model for estimating survival in patients with cancer and symptomatic metastases of the long bones, evaluate current (surgical) treatment modalities and trends, and provide rationale for future prospective randomized trials. As a result, the OPTIModel was developed: an easy-to-use prognostic model that categorises patients into four clinically relevant survival categories based on only three variables (tumour type, Karnofsky Performance Score, visceral/brain metastases). To enable easy use of the model, an app was created (OPTIModel). Futhermore, this thesis shows that almost all treatments of pathologic fractures are based on expert opinion and small, retrospective cohorts, as opposed to large, prospective (randomized) trials, which is interesting in an era of evidence based medicine. This confirms the need of a prospective, multicenter cohort, which was designed and implemented accordingly. Show less
This thesis focuses on several aspects of quality of life in patients with painful bone metastases, treated with palliative radiotherapy within the randomized Dutch Bone Metastasis Study.The... Show moreThis thesis focuses on several aspects of quality of life in patients with painful bone metastases, treated with palliative radiotherapy within the randomized Dutch Bone Metastasis Study.The detailed course of quality of life after treatment was studied, as was the relation between a pain response and quality of life. Also prognostic factors predicting a pain response, psychological distress, side-effects and survival were studied. Show less
In this thesis, quantitative and qualitative evidence was gathered in an attempt to improve and extend the current sexual health care of gynaecological cancer survivors. Although surgery has a... Show moreIn this thesis, quantitative and qualitative evidence was gathered in an attempt to improve and extend the current sexual health care of gynaecological cancer survivors. Although surgery has a major impact on sexual functioning, vaginal changes and symptoms have been shown to be more profound after intensive radiotherapy. Therefore, the studies in this thesis were especially focused on gynaecological cancer survivors who received radiotherapy, and mainly concerned cervical cancer patients; a relatively young patient population often treated with intensive external-beam radiation therapy (EBRT) in combination concurrent chemotherapy, and intrauterine and vaginal brachytherapy (BT), although the results are equally relevant to other gynaecological cancer patients treated with EBRT with or without BT. In order to assess what type of patient education and/or support would be needed to minimise the impact of gynaecological cancer treatment on sexual functioning, and to improve the survivors’ sexual recovery we followed several approaches: assessment of survivors’ experience with sexual distress after treatment, and unmet needs for psychosexual counselling and support; it was explored how survivors and professionals could best deal with treatment-induced vaginal changes; and, partly based on the previous findings, a sexual rehabilitation intervention was developed and evaluated in a pilot study. Show less
In this thesis long-term effects and quality of life after treatment for rectal cancer are evaluated. Long-term data were assessed from the TME trial. In this trial 1530 Dutch patients with... Show moreIn this thesis long-term effects and quality of life after treatment for rectal cancer are evaluated. Long-term data were assessed from the TME trial. In this trial 1530 Dutch patients with rectal cancer were included between 1996 and 1999. These patients were randomly assigned to total mesorectal excision (TME) or to short-course preoperative radiotherapy (5x5 Gy) followed by TME surgery. Show less
