High-precision Bladder Cancer Irradiation in the Elderly: Clinical Results for a Plan-of-the-day Integrated Boost Technique with Image Guidance Using Lipiodol Markers
Introduction
For curative treatment of muscle-invasive bladder cancer (MIBC) there is a choice between surgery or radiotherapy, with or without (neo-)adjuvant chemotherapy [1]. For most elderly patients, surgery is not an option as it may have a considerable impact on the condition of frailer patients. During conventional radiotherapy, the whole bladder is usually irradiated with a margin of 1–1.5 cm. Visibility of the primary tumour is poor and the unpredictable shape and deformations of the bladder needs to be compensated. The major concern with standard treatment is the large volume of healthy tissue that is irradiated to high dose levels [1], [2], [3]. The majority of patients treated with a curative irradiation regimen receive whole–bladder irradiation with conventional doses of 60–65 Gy [2], [4] or hypofractioned treatments with doses of 50–57.7 Gy in fractions of 2.5–2.88 Gy [2]. However, in an alternative strategy the tumour is targeted, which reduces the dose to the healthy part of the bladder and surrounding tissues [2], [3], [4], [5], [6]. Tumour identification on computed tomography (CT) scans is challenging since most patients undergo transurethral resection of tumour (TURT) or are treated with neoadjuvant chemotherapy, which reduces the tumour bulk [1], [2], [3]. Pos et al. [3] demonstrated that use of Lipiodol (radioopaque poppy seed oil) injections to precisely mark the lesion to target is a feasible solution. Using integrated cone-beam CT (CBCT) it is possible to visualise the bladder and the marked location of the tumour and adjust the treatment position accordingly [2], [3].
This paper is an update of our previous article in 2012, which described the combined approach of Lipiodol demarcation and plan-of-the-day integrated boost (LPOD) used in 20 patients in our hospital [2]. This paper focuses on our continued clinical experience with this technique and results after longer follow-up.
Section snippets
Patients
Patients treated between September 2008 and September 2016 were eligible for inclusion if they had T2–T4N0M0 grade 2–3 MIBC and had undergone radical TURT 4–8 wk before radiotherapy. Patients had to be capable of understanding the treatment procedure. We excluded patients with previous pelvic radiotherapy or a tumour volume >50% of the bladder wall surface. A hip prosthesis was also an exclusion criterion, since an artificial hip results in distorted images on CT scans and thus less reliable
Patient characteristics
In total, 204 patients with MIBC were treated between September 2008 and September 2016 in our radiotherapy department. The median age at the start of treatment was 80.14 yr. Of the 204 patients, 38 male and six female patients were treated using the LPOD technique. The median age of the selected patients (Table 1) at the start of treatment was 81 yr (range 65–98). Tumour stage varied from T2 (39 patients, 88.6%) to T3 (4 patients, 9.1%) and T4 (1 patient, 2.3%). One patient had a bladder
Discussion
Radiotherapy is an effective treatment for MIBC and is mostly used in patients who are not fit for cystectomy. In accordance with the exclusion criteria, approximately 20% of all patients with high-grade MIBC referred for curative radiotherapy were treated using the LPOD technique. Owing to the high number of comborbidities (mainly cardiovascular disease and poor overall condition) no concurrent chemoradiation was chosen. The remaining 160 patients received treatment with conventional
Conclusions
LPOD is feasible as a first-line treatment option in elderly patients with limited-volume T2–T4N0M0 grade 2–3 MIBC who are unsuitable for surgery. Our study demonstrated a small risk of local recurrence, high cancer-specific survival, minimal toxicity, and a good overall survival rate.
Author contributions: Alexander J.W. Beulens had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: van
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