Research ArticleClinical (Oncology: Melanoma/Skin)

18F-FDG PET/CT for Posttreatment Surveillance Imaging of Patients with Stage III Merkel Cell Carcinoma

Sonia Mahajan, Christopher A. Barker, Audrey Mauguen, Sandra P. D’Angelo, Randy Yeh and Neeta Pandit-Taskar
Journal of Nuclear Medicine June 2022, 63 (6) 906-911; DOI: https://doi.org/10.2967/jnumed.121.262882

Article Figures & Data

Figures

  • Figure
  • FIGURE 1.
    FIGURE 1.

    Asymptomatic 70-y-old woman with left arm MCC (s/p excision, left axillary lymphadenectomy, radiation to axilla) underwent surveillance 18F-FDG PET/CT scan 3.3 mo after treatment. 18F-FDG PET/CT (A; maximum-intensity projection, arrow) scan revealed solitary focal 18F-FDG uptake in left pelvis (B; fused PET/CT, SUV 9, arrow) in a nodular soft-tissue-density lesion in left adnexa (C; axial CT, arrow). USG pelvis showed solid mass in left ovary measuring 1.8 x 1.4 x 1.6 cm, corresponding to site of abnormality on 18F-FDG PET/CT. Patient underwent salpingo-oophorectomy and pathology was positive for MCC. s/p = status post; USG = ultrasound.

  • FIGURE 2.
    FIGURE 2.

    Receiver-operating-characteristic (ROC) curve for benign versus malignant lesion prediction based on SUVmax. FPR = false-positive rate; TPR = true-positive rate.

  • FIGURE 3.
    FIGURE 3.

    Swimmer plot illustrating information about local and distant recurrences, confirmed on pathology, during follow-up on surveillance 18F-FDG PET/CT scans since end of primary treatment for all included stage IIIA known primary (KP), IIIA unknown primary (UP), and IIIB MCC patients (n = 61).

  • FIGURE 4.
    FIGURE 4.

    OS of patients based on findings and timing of 18F-FDG PET/CT scan (A, at 3-mo; B, at 6 mo, and C, at 12 mo after definitive treatment, respectively).

Tables

  • TABLE 1.

    Patient, Tumor, and 18F-FDG PET/CT Scan Characteristics

    CharacteristicData
    No. of patients61
    Sex (n)
     Male44 (72%)
     Female17 (28%)
    Mean age (±SD) at the time of diagnosis (y)69 ± 13.0 (range, 25–93)
    Site of primary disease (n)
     Cheek/chin5 (8.1%)
     Ear/eyelid/nose4 (6.6%)
     Forehead/scalp5 (8.1%)
     Neck node2 (3.3%)
     Axilla4 (6.6%)
     Back/chest2 (3.3%)
     Groin11 (18.0%)
     Buttocks10 (16.3%)
     Finger/hand2 (3.3%)
     Forearm/elbow/arm8 (13.2%)
     Knee/leg/thigh8 (13.2%)
    Stage of primary disease at diagnosis (n)
     Stage IIIA (known primary)23 (37%)
     Stage IIIA (unknown primary)20 (33%)
     Stage IIIB18 (30%)
    Prior treatment received (n)
     Surgery20 (33%)
     Surgery + chemotherapy/ radiation/chemoradiation38 (62%)
     Chemoradiation3 (5%)
     Number of 18F-FDG PET/CT scans221
    Scans performed per patient (n)
     1–443
     5–1018
  • TABLE 2.

    Univariate and Multivariate Prognostic Models for OS

    UnivariateMultivariate
    VariableHR95% CIPHR95% CIP
    18F-FDG PET/CT scan, positive15.74.34, 56.5<0.001———
    SUVmax (for 1 unit)1.271.17, 1.39<0.0011.171.05, 1.310.006
    No. of positive lesions (for 1 lesion)1.451.27, 1.64<0.0011.601.25, 2.04<0.001
    Stage0.160.05
     IIIA (KP)Ref.Ref.
     IIIA (UP)0.270.06, 1.270.090.01, 0.99
     IIIB0.860.28, 2.640.380.08, 1.94

    • KP = known primary; Ref. = reference; UP = unknown primary.

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