Page 82 - ARNM-3-2

Advances in Radiotherapy
& Nuclear Medicine Radiotherapy in node-positive bladder cancer

Radical cystectomy (with or without neoadjuvant There is a lack of good-quality evidence on the role
chemotherapy [NAC]) is the standard of care for patients of TMT in treating patients with node-positive disease.
with localized muscle-invasive bladder cancer (MIBC). Delivering the prescribed dose to the target volume without
3,4
Trimodality therapy (TMT) is a bladder preservation raising the risk of acute and long-term toxicity is one of the
strategy that combines radiotherapy (RT) with concurrent primary challenges when using RT to treat patients with
radiosensitizers after maximal transurethral resection of node-positive bladder cancer. However, the complex and
the bladder tumor (TURBT). The historical view of radical dynamic manipulation of radiation beams has been made
cystectomy being the gold standard of care in MIBC has possible by advances in RT planning conformal approaches
been challenged by more recent data that have shown such as IMRT, enabling proper target coverage while
TMT to be equivalent, if not superior, in terms of disease sparing nearby organs at risk (OAR). In a study conducted
11
control. 5 by Sondergaard et al., 16 patients were treated with IMRT,
delivering 60 Gy to the bladder and 48 Gy to the pelvic lymph
Radical RT protocols in the UK usually employ a
conventionally fractionated dose of 64 Gy in 32 fractions or nodes. The dose-volume histogram parameters for relevant
normal tissues (e.g., bowel, bowel cavity, rectum, and
a hypofractionated dose of 55 Gy in 20 fractions delivered femoral heads) for the IMRT plans were compared with the
to the entire bladder using a three-dimensional conformal corresponding dose-volume histogram from the conformal
technique or intensity-modulated RT (IMRT). Supporters sequential boost technique. IMRT demonstrated statistically
1
of conventional fractionation argue that a lower dose per significant sparing of normal tissue. For the bowel, a
fraction should result in a superior therapeutic index – significant reduction was observed at all dose levels between
characterized by a higher probability of tumor control 20 and 50 Gy (p<0.05), such as from 180 to 121 cm at 50 Gy.
3
and reduced rates of late toxicity – due to the presumed Similar patterns were observed for the bowel cavity, rectum,
high α/β ratio of bladder cancer. However, a recent meta- and femoral head. The acute gastrointestinal (GI) toxicity was
analysis of individual patient data from the BCON and 38%. IMRT to the urinary bladder and elective lymph nodes
BC2001 trials, which allowed both dosing regimens, resulted in considerable sparing of normal tissue compared
demonstrated similar toxicity rates and better locoregional to the conformal sequential boost technique.
control with hypofractionation. 6
To explore the use of TMT for treating patients with
The survival outcomes of localized MIBC have node-positive bladder cancer post-surgery, we developed
significantly improved over the years. In a propensity- a unique RT protocol utilizing volumetric modulated arc
matched score analysis of MIBC treated with cystectomy therapy (VMAT). The purpose of this study is to examine
or TMT, the 5-year disease-specific survival rate was the evolution of the VMAT protocol and to assess the
73.2% and 76.6% in the cystectomy and TMT groups, efficacy of RT in managing patients with primary bladder
respectively. However, there is limited data regarding the cancer and potentially involved locoregional pelvic lymph
7
optimal management of patients with pelvic node-positive, nodes.
non-metastatic bladder cancer, and the prognosis of these
patients remains uncertain and poorly defined. A growing 2. Materials and methods
body of evidence indicates that this is a unique clinical 2.1. Study population
entity with an intermediate prognosis that falls between
advanced metastatic bladder cancer and bladder-confined The novel VMAT-RT protocol was implemented in
MIBC. 2020, involving the delivery of 57.5 Gy in 23 fractions to
the bladder and 46 Gy in 23 fractions to the nodes. We
The clinical management of bladder cancer, whether
clinically or pathologically node-positive, has seen reviewed the RT planning systems (Varian Eclipse, US)
to identify patients who received treatment with this
significant variation as practice patterns have continued protocol between June 2020 and August 2024. A total
to change. A palliative approach that involves systemic of 17 patients who were treated with this protocol were
therapy alone, with local therapy saved for symptom identified. All patients were discussed at the urology multi-
control, is preferred by certain multidisciplinary teams. disciplinary team meeting, had a histological confirmation
Others advocate for a curative-intent strategy that includes of malignancy, and underwent computed tomography
NAC with either cystectomy or TMT. 8,9 (CT) scans for staging of their disease. Based on the CT
Although several studies have shown that neoadjuvant scan, all patients had disease limited to the pelvis, with no
and adjuvant chemotherapy reduces the rate of distant lymphadenopathy observed above the aortic bifurcation. As
metastases, individuals with node-positive illness are also none of the patients were deemed appropriate for surgery,
at a considerable risk of locoregional recurrence. 3,4,10 radical RT (with or without concurrent chemotherapy)

Volume 3 Issue 2 (2025) 74 doi: 10.36922/ARNM025090009