Oropharyngeal Cancer with Distant Metastasis: A Case-Based Imaging Insight Using FDG PET/CT

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Oropharyngeal Cancer with Distant Metastasis: A Case-Based Imaging Insight Using FDG PET/CT

Introduction

Oropharyngeal cancer, a malignancy arising in the posterior portion of the oral cavity—including the tonsils, base of the tongue, and soft palate—is becoming increasingly prevalent worldwide. One of the key drivers behind this rise is the surge in human papillomavirus (HPV)-associated subtypes, particularly among younger populations. Due to the cancer's insidious onset and rapid metastatic potential, early and accurate staging through advanced imaging modalities like FDG PET/CT is critical for improving outcomes.

This blog post presents a compelling case of a 53-year-old woman diagnosed with metastatic oropharyngeal cancer via FDG PET/CT, illustrating the pathophysiology, clinical presentation, imaging features, and therapeutic implications of this aggressive disease.

Case Presentation


  • Patient: 53-year-old female

  • Initial Complaint: Left-sided neck mass

  • Histology: Poorly differentiated adenoid cystic carcinoma (ACC)

  • Initial Imaging: Contrast-enhanced CT revealed asymmetrical thickening and a necrotic mass in the left oropharynx

  • FDG PET/CT Findings:

    • Intense FDG uptake in the left oropharyngeal wall (primary lesion)

    • Bilateral cervical lymph node metastasis

    • Multiple hypermetabolic pulmonary nodules

    • FDG-avid lesions in the liver, scapula, sacrum, and radius, suggesting widespread metastasis

Etiology and Epidemiology

  • Primary Risk Factor: HPV-16 infection

  • Other Contributors: Chronic tobacco use and excessive alcohol consumption

  • Demographics:

    • Typically affects individuals over 50

    • HPV-positive variants are increasingly observed in patients aged 40–50

    • Historically male-dominant, but female incidence is rising

Pathophysiology

In HPV-related oropharyngeal cancers, viral oncoproteins E6 and E7 inactivate tumor suppressor proteins p53 and Rb, leading to unregulated cellular proliferation and carcinogenesis. In contrast, HPV-negative cases are often linked to chronic mucosal irritation due to smoking and alcohol, resulting in accumulated genetic mutations.

Clinical Features

  • Neck mass (most common initial symptom)

  • Dysphagia (difficulty swallowing)

  • Persistent sore throat

  • Voice changes (hoarseness)

  • Unintentional weight loss

  • Palpable oropharyngeal mass in advanced cases

Imaging Highlights

Role of FDG PET/CT:

FDG PET/CT is indispensable in the staging and systemic evaluation of oropharyngeal cancer. It provides both anatomical and functional data by highlighting regions with increased glucose metabolism, an indicator of malignant activity.

Key findings from the case:

  • Intense FDG uptake in the left oropharynx indicates a primary tumor

  • Bilateral cervical lymphadenopathy

  • Multiple FDG-avid lung nodules

  • Metastatic deposits in the liver, scapula, sacrum, and forearm bones

These findings collectively confirm a diagnosis of advanced-stage oropharyngeal cancer with widespread metastasis.

Treatment Strategy

Case Approach:

  • The patient received palliative chemotherapy due to the advanced stage and systemic dissemination.

Standard Options:

  • Localized disease: Radiation or concurrent chemoradiotherapy (CCRT)

  • Advanced disease: Systemic chemotherapy ± immunotherapy

  • HPV-positive tumors: Typically respond better to treatment and have improved prognosis

Prognosis

  • HPV-positive oropharyngeal cancers: 5-year survival rate of 75–80%

  • HPV-negative types: 5-year survival drops to 30–50%

  • Cases with distant metastasis, such as the one described, often have poor outcomes with a median survival <12 months

Quiz Section

1. What is the primary role of PET/CT in oropharyngeal cancer?

A. Tumor histological differentiation
B. Functional lymph node analysis
C. Staging and metastasis evaluation
D. Guiding radiation therapy

Explanation: PET/CT is a powerful tool for assessing the metabolic activity of both primary and metastatic lesions. It plays a critical role in determining the cancer stage, identifying distant metastases, and guiding treatment decisions.

2. Which of the following is NOT a known risk factor for oropharyngeal cancer?

A. HPV-16 infection
B. Chronic smoking
C. High-fat diet
D. Excessive alcohol consumption

Explanation: HPV infection, tobacco use, and alcohol are established risk factors for oropharyngeal cancer. A high-fat diet, although a risk for some other cancers, has not been conclusively linked to oropharyngeal malignancies.

Conclusion

This case highlights the importance of integrating clinical evaluation with high-resolution imaging, such as FDG PET/CT, in the diagnosis and management of oropharyngeal cancer. Early detection of metastatic spread can dramatically alter the therapeutic approach and expected outcomes. The rising prevalence of HPV-related cases also underlines the need for vaccination strategies and public awareness.

References

  1. Ang KK, Harris J, Wheeler R, et al. Human papillomavirus and survival of patients with oropharyngeal cancer. N Engl J Med. 2010;363(1):24–35. doi:10.1056/NEJMoa0912217

  2. Lechner M, Liu J, Masterson L, Fenton TR. HPV-associated oropharyngeal cancer: Epidemiology, molecular biology and clinical management. Nat Rev Clin Oncol. 2022;19(5):306–319. doi:10.1038/s41571-022-00612-4

  3. Mehanna H, Paleri V, West CM, Nutting CM. Oropharyngeal cancer: United Kingdom National Multidisciplinary Guidelines. J Laryngol Otol. 2016;130(S2):S90–S96. doi:10.1017/S0022215116000449

  4. Adams HJ, Kwee TC, de Keizer B, Fijnheer R, de Klerk JM, Nievelstein RA. FDG PET/CT for detecting distant metastases in oropharyngeal squamous cell carcinoma. Eur J Radiol. 2014;83(4):682–687. doi:10.1016/j.ejrad.2014.01.012

  5. Lassen P, Eriksen JG, Krogdahl A, Therkildsen MH. The role of radiotherapy in the management of HPV-related oropharyngeal cancer. Nat Rev Clin Oncol. 2023;20(2):87–100. doi:10.1038/s41571-022-00653-9


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