Is routine pelvic surveillance imaging necessary in patients with Wilms tumor?

Abstract

Background It is unclear if routine pelvic imaging is needed in patients with Wilms’ tumor. Thus, our primary objective examined the role of routine pelvic computed tomography (CT) in a cohort of pediatric patients with Wilms’ tumor. Methods With IRB approval we retrospectively identified 110 Wilms’ tumor patients diagnosed between January 1999 and December 2009; surveillance imaging continued through March 2011. We estimated survival (OS) and event-free survival (EFS), and dosimetry from dose length product (DLP) conversion to effective dose (ED) for every CT in a subgroup of 80 patients scanned using contemporary scanners (2002–2011). MOSFET dosimeters were placed within organs of anthropomorphic phantoms to directly calculate truncal ED. EDDLP was correlated with EDMOSFET to calculate potential pelvic dose savings. Results Eighty patients underwent 605 CT examinations containing DLP information: 352 chest, abdomen and pelvis, 123 chest-abdomen, 102 chest only, 18 abdomen-pelvis, 9 abdomen only, one limited to pelvis. Respective 5-year OS and EFS estimates were 92.8% ± 3.0% and 2.6% ± 4.3%. Sixteen patients (16/110; 15%) relapsed a median of 11.3 months (range, 5.0 months to 7.3 years) after diagnosis; four died of disease recurrence. Three patients developed pelvic relapse, all symptomatic. Estimated ED savings from gender-neutral CT surveillance performed at 120 kVp without pelvic imaging was calculated: 30.5%, 30.4%, 39.4%, and 44.9% for the average 1, 5, 10, and 15 year old patient, respectively. Conclusions Omitting pelvic CT from routine off-therapy follow-up of Wilms’ tumor patients saves an average 30–45% effective dose without compromising disease detection.

Relapse of Wilms' tumour and detection methods: a retrospective analysis of the 2001 Renal Tumour Study Group–International Society of Paediatric Oncology Wilms' tumour protocol database

“…Low dose CT chest (1-2 mSV/scan) or abdomen might be able to detect smaller nodules but will increase the radiation burden and the value of routine CT surveillance is debated. 12,[23][24][25][26] Mortality rate was nearly twofold for patients presenting with clinical symptoms between planned surveillance compared to patients with asymptomatic relapse captured by planned surveillance visits. Despite this remarkable difference, the benefits of surveillance are less certain as the mortality difference may be due to other factors such as location of the tumour and tumour-specific growth rate ie, 'biological aggressiveness' as a confounding variable.…”

The role of imaging in the initial investigation of paediatric renal tumours

“…Whilst this is an important consideration for long term follow-up, MRI is not a risk-free long term strategy as evidenced by the recent concerns about the neurocognitive effects of general anaesthetic and the controversial issue of gadolinium accumulation in the deep white matter of the brain 21,22 . It has been shown that omitting the pelvis in follow-up CT studies can reduce the effective dose of the study by up to 45% without significant reduction in relapse detection 23,24 .…”

Routine surveillance imaging after end of therapy for pediatric extracranial tumors: A retrospective analysis

“…Two studies focusing on children with sarcoma and rhabdomyosarcoma, respectively, showed that regular imaging studies neither facilitated earlier detection of recurrence nor improved overall survival . In Wilms tumor, routine surveillance CT scans of the pelvis were shown to be unnecessary, recommending substitution with abdominal ultrasound, and in patients with Neuroblastoma, CT scans seem to minimally contribute to detection of recurrences …”