ONCOTHESIS

Improving post-implant evaluation of permanent seed implant brachytherapy for prostate cancer

Permanent brachytherapy with radioactive seeds is a widely available and effective treatment for low-risk prostate cancer patients. An important factor affecting tumour control and complication rates is implant quality. Therefore, dosimetric post-implant evaluation (postplanning) is recommended as a standard-of-care practice to ensure the quality of the implant technique and to obtain dosimetric data for establishing dose-response relationships. Currently, the relationship between delivered dose and tumour response is not clear, which to a large extent may be attributed to the uncertainties related to post-implant dosimetry. Seed reconstruction, prostate delineation and image fusion inaccuracies play an important role in this, though it is not known how large their impact is on the post-planning evaluation parameters. In this research, we quantified and compared these uncertainties for different imaging techniques. The overall aim was to improve the quality of post-implant evaluation in order to obtain more consistent and reliable dosimetric post-plan information.

(BELG J MED ONCOL 2014;8(1):18–20)

The role of imaging in a patient-tailored approach for prostate cancer

Summary

One of the obstacles for the adequate treatment of prostate cancer is the lack of reliable modalities to detect lymph node involvement in newly diagnosed patients. Until now, the only accurate solution is to perform an extended lymph node dissection. In this dissertation, investigated the role of choline positron emission tomography-computed tomography, diffusion-weighted magnetic resonance imaging and a sentinel node procedure for nodal staging were investigated showing that these novel approaches are not reliable enough to substitute for a lymphadenectomy. Furthermore, we reported which regions are of most importance if a staging lymphadenectomy is performed.

A second part, focused on the accurate localisation of the macroscopic tumour nodule within the prostate since delivering a higher radiation dose to this specific region might reduce the chances of local recurrence after radiotherapy. Therefore, the performance of the aforementioned imaging modalities were tested in the detection of intraprostatic tumour nodule(s). In conclusion, combining different functional magnetic resonance imaging modalities improved visualisation of the tumour but that the additional value of a positron emission tomography scan in this specific setting was limited.

(BELG J MED ONCOL 2013;7(5):156–58)

Breast cancer irradiation: optimisation of treatment techniques and evaluation of toxicity

Summary

Radiotherapy plays an important role in the treatment of breast cancer patients as it has shown to improve both local control and survival.¹ To further improve the therapeutic ratio, it is important to optimise radiotherapy dose distributions using modern radiotherapy techniques. This is particularly true when the locoregional lymph nodes are included in the target volume, as the resulting complex target volume, in close proximity of the heart and lungs, makes treatment planning more challenging.² With improving survival rates for breast cancer patients, prevention of long-term treatment-related toxicity becomes more important. Therefore, a better understanding of the occurrence of radiotherapy-induced late cardiopulmonary side-effects is needed.

(BELG J MED ONCOL 2013;7(4):123–6)

Clinical implementation of frameless radiosurgery

Summary

Stereotactic radiosurgery is a treatment technique that uses a single high ablative dose of radiation to benign and malignant laesions while sparing healthy brain tissue. Several systems have been developed to perform this technique, and these differed in the way the irradiation was performed. An accurate positioning, immobilisation of the patient and a precise localisation of the laesion are essential. Traditionally, this was performed with a headring screwed onto the patient’s skull (frame-based technique). The positioning is achieved using a localiserbox, mounted on the invasive headring and stereotactic coordinates, obtained through the planning system. With recent developments in radiotherapy, this high precision positioning can nowadays also be performed without the invasive headring. This non-invasive approach, called frameless, improves patient comfort and uses a mask system to immobilise the patient and image-guidance to accurately position the patient on the basis of anatomy. The Novalis system (Brainlab AG) at the UZ Brussel can use both a frame-based and frameless approach. Frameless radiosurgery is carried out with a mask device and two stereoscopic x-ray images. This innovative frameless positioning technique showed equivalent positioning accuracy and immobilisation characteristics to the invasive frame-based technique.

(BELG J MED ONCOL 2013;7(3):93–97)

Introducing Intensity-Modulated Arc Therapy in the multimodality treatment of pelvic gynaecological tumours: thinking out of the box

Summary

The need for an efficient, fast technique to irradiate large concave targets lead to the introduction of intensity-modulated arc therapy in the multimodality treatment of pelvic gynaecological tumours. Postoperatively irradiated cervical and endometrial cancer patients benefit by reduced toxicity rates. In locally advanced cervical cancer the use of intensity-modulated arc therapy with a simultaneously integrated boost allows for a safe hysterectomy, resulting in promising control and survival rates. In chemotherapy-resistant ovarian cancer patients with peritoneal carcinomatosis, the use of intensity-modulated arc therapy facilitates a safe whole abdominopelvic irradiation, one of the few effective solutions for patients with bowel obstruction. Continuing efforts should be made to further decrease toxicity and increase response rates and survival in the multimodality treatment of pelvic gynaecological tumours.

(BELG J MED ONCOL 2013;7(2):53–56)

Real-life outcome of optimally treated patients with malignant glioma

Most outcome studies of malignant glioma are performed in tertiary referral centres and suffer from extensive selection and referral bias. The results are difficult to interpret due to combined data of maximally treated patients and partially treated patients. We prospectively studied the outcome of an unselected sequential cohort of 29 patients with malignant glioma who received maximal treatment according to present standard of care defined as macroscopic resection followed by chemoradiotherapy and adjuvant temozolomide. The median overall survival in our cohort was 13,3 months (SD 10,9 months). 6-month survival rate of 82,7%, and 12-month survival rate of 65,5%. 6-month progression free survival rate (PFS) of 75,8%. 12-months PFS of 48,3%. 2-year survival was 10,3%. However, the 5-year survival was 0%. In our unselected sequential cohort of newly diagnosed malignant glioma patients we observed good tumour control at one year, but not at two years. (BELG J MED ONCOL 2012;6:204–206)

Prognostic factors in ductal carcinoma in situ (DCIS)

Ductal carcinoma in situ of the breast (DCIS) is a clinical entity which is discovered as microcalcifications on screening mammography, it rarely represents a palpable disease. Asymptomatic women with DCIS receive treatments that are similar to women with invasive breast cancer and therefore experience substantial psychological distress despite the fact that they have an excellent prognosis and normal life-expectancy. It is also true that, in spite of aggressive treatment approaches, some patients do recur.

In analogue with invasive breast cancer, DCIS is a heterogeneous disease with different prognostic profiles. The high incidence of DCIS and variations in its treatment with different outcomes led to the introduction of the Van Nuys Prognostic index (VNPI) developed in 1996 by Silverstein. This index is a simple decision-making tool to improve or at least standardise DCIS care and had been incorporated in our daily practice since 1997. Data on that experience were analysed. We tried to obtain a better understanding of the molecular behaviour of DCIS laesions and looked for predictive and prognostic markers associated with disease-free survival (DFS). The next step was the use of micro-array analysis with the Genomic Grade Index (GGI), based on four proliferation genes, and the proliferation index Ki-67. These two indices, which are considered to be predictive for the behaviour of invasive breast cancer, were incorporated into the VNPI. Furthermore, we looked if the tumour microenvironment might play a crucial role in local relapse of DCIS and risk of subsequent invasive disease. (BELG J MED ONCOL 2012;6:164–168)