Metastatic Urinary Bladder Carcinoma on Palliative Chemotherapy Showing Rapid Progression on Interim Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

A 55-year-old male presented with painless hematuria for two months. He had no associated fever or weight loss. Contrast-enhanced computed tomography of the abdomen and pelvic showed a mass in the UB. A transurethral biopsy confirmed muscle-invasive bladder cancer (MIBC). The pretreatment fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) revealed aUB mass with nontracer avid sub-centimeter size pelvis lymph node (LN). Because of suspicious metastatic lung nodules, he received four cycles of carboplatin and gemcitabine-based palliative chemotherapy. His chemotherapies were uneventful, and hematuria subsided. The patient was referred for a follow-up interim FDG PET/CT scan to evaluate treatment response. It showed rapid progression of the metastatic disease burden [Figures 1 and 2].

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Figure 1

(a) Maximum intensity projection images of baseline 18-F fluorodeoxyglucose positron emission tomography/computed tomography revealed fluorodeoxyglucose avid lesion in the urinary bladder (black arrow) and few nodules in the lungs (blue arrow). (b) Fused whole-body coronal images show fluorodeoxyglucose avid thickening of urinary bladder (black arrow). (c and d) Follow-up maximum intensity projection and fused coronal images reveal residual thickening in the urinary bladder. Apart from that, multiple areas of uptake are noted in retroperitoneal lymph nodes (blue arrow), mediastinal lymph node, lung (blue arrow), and liver (red arrow)

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Figure 2

Baseline (a-d) trans-axial images fused positron emission tomography/computed tomography show mass involving the anterosuperior wall of urinary bladder (white arrow). A faintly fluorodeoxyglucose avid nodule is noted in the upper lobe of the left lung (red arrow). The liver and retroperitoneum are unremarkable. Follow-up fluorodeoxyglucose positron emission tomography/computed tomography images (e-h) reveal residual primary (white arrow in e) lesion of the urinary bladder. Fluorodeoxyglucose avid nodule in the upper lobe of the left lung (red arrow in f) with supraclavicular and mediastinal lymph nodes (blue arrows) are seen. Extensive fluorodeoxyglucose avid (red arrows in g) hepatic lesions are noted with a bone lesion in the D8 vertebra (white arrow in g). Multiple fluorodeoxyglucose avid (white arrow, h) retroperitoneal lymph nodes are noted

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Bladder cancer (BC) is the ninth most common cancer in developed countries with poor prognosis and outcome. It is mainly due to delayed diagnosis and limited treatment possibilities. It arises from the urothelial cell lining.[1] The main risk factor for BC is tobacco smoking.[2] At the time of diagnosis, approximately 75% of these have non-MIBC, with the remaining 25% having MIBCor metastatic disease. Early diagnosis and multimodality therapy could result in optimal outcomes. However, metastatic disease is generally incurable, with a dismal 5-year overall survival rate of 15%.[3] Tumors in the advanced T category and atypical histologic features metastasize earlier. It commonly metastasis to the LNs, bones, lungs, liver, and peritoneum.[4]

The metastatic disease had limited treatment options for decades. Cisplatin-based chemotherapy remained a mainstay of treatment. However, with recent advancements, various new therapeutic agents are available. The use of immune checkpoint inhibitors (ICIs) directed at programmed cell-death protein 1 has led to unprecedented survival advantages in selected patients. Atezolizumab and pembrolizumab (both ICIs) may be given in platinum-ineligible advanced UC patients. Recently erdafitinib, a pan-FGFR inhibitor, is approved for advanced metastatic UC.[5]

FDG/PET is increasingly used in the initial metastatic workup and treatment response evaluation. The pooled sensitivity and specificity of FDG PET/CT for staging or restaging are 82% and 89%, respectively.[6] It is found more accurate than CT in the presurgery stage. Following neoadjuvant chemotherapy in MIBC, FDG-PET/CT demonstrated 75% sensitivity and 90% specificity in identifying a complete pathological response.[7] To access the response of first-line systemic chemotherapy (cisplatin and gemcitabine), FDG PET/CT outperformed CT interpretation alone based on Response Criteria in Solid Tumors RECIST criteria.[8] FDGPET/CT predicts progression-free survival and overall survival after two cycles of palliative chemotherapy in metastatic BC.[9] FDG PET/CT helps to detect recurrence and change in treatment decisions in approximately 40% of the patients.[10] Rapid asymptomatic progression of the metastatic BC is uncommon and needs to be reported. This case highlights the value of interim PET-CT to evaluate the treatment response in metastatic BC.