ASCO GU 2020: PET Imaging in Penile Cancer

San Francisco, CA (UroToday.com) A discussion on the use of PET imaging in penile cancer was given by Dr. Priya Bhosale in this session. Penile cancer accounts for <1% of all cancer diagnosed in men. Approximately 2,080 men will be diagnosed with penile cancer in the US alone. Over 63% of them are linked with HPV, and the 5-year survival rate of localized penile cancers is relatively high (85%). However, when there is regional lymphadenopathy, the 5-year survival rate is 59% and with distant metastases it is 11%.  

Clinical staging of penile cancer involves palpation of the primary tumor and the inguinal nodes. However, as expected, this can often result in under-staging of the disease. Therefore, imaging modalities must be used for staging. These include MRI, CT and PET/CT. 

MRI can accurately predict pathological stage in 72% of cases compared to 52% using only physical examination. It can detect tunica albuginea invasion with a sensitivity of 82% and specificity of 74%, and it can detect urethral invasion with a sensitivity of 63% and specificity of 82% (Figure 1). For T staging MRI is the best modality due to its excellent soft tissue resolution. 

Figure 1 – MRI for the staging of penile cancer: 
ASCO GU 2020 Figure 1 MRI for the staging of penile cancer

Dr. Bhosale concluded her talk discussing the use of PET/CT in penile cancer. This imaging modality can be used in penile cancer, showing a sensitivity of 75% and specificity of 75% for assessment of the primary malignancy. An important tool in PET/CT is the pSUVmax which was higher in patients with tumors infiltrating subepithelial connective tissue, blood and lymphatic vessels and those with poor differentiation (pT1b and above). 

PET/CT can be used for staging and to assess lymph node spread as well. Penile cancer demonstrates a predictable pattern of metastatic spread. Commonly, it spreads to the sentinel lymph node, superficial inguinal lymph nodes, inferior and deep inguinal nodes and lastly to the pelvic nodes. PET/CT should be used for staging in patients with unresectable inguinal disease, patients with comorbidities (to prevent unnecessary inguinal surgery), and for follow-up in patients who undergo chemotherapy or radiation therapy as neoadjuvant or primary therapy. 

Presented by: Priya Bhosale, MD, University of Texas MD Anderson Cancer Center, Houston, Texas

Written By: Hanan Goldberg, MD, Urology Department, SUNY Upstate Medical University, Syracuse, NY, USA  @GoldbergHanan at the 2020 Genitourinary Cancers Symposium, ASCO GU #GU20, February 13-15, 2020, San Francisco, California
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