Prospective Assessment of Fluorine-18-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography (FDG-PET/CT) for Early Identification of Checkpoint-Inhibitor-Induced Pseudoprogression.

The activity of immune checkpoint inhibitors (ICIs) in patients with metastatic melanoma is often monitored using fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) scans. However, distinguishing disease progression (PD) from pseudoprogression (PsPD), where increased FDG uptake might reflect immune cell activity rather than tumor growth, remains a challenge. This prospective study compared the efficacy of dual-time point (DTP) FDG-PET/CT with modified response criteria (PERCIMT) in differentiating PsPD from PD. From July 2017-January 2021, 41 patients suspected to have PsPD on an evaluation scan were prospectively included (29 evaluable). A subsequent DTP FDG-PET/CT scan was conducted within 14 days, followed by a confirmatory FDG-PET/CT scan. Additionally, PERCIMT were applied. DTP FDG-PET/CT identified 24% with PsPD and 76% with PD. Applying PERCIMT criteria, 69% showed PsPD, while 31% had PD. On follow-up, 10 patients (34%) demonstrated confirmed PsPD, while 19 (66%) exhibited PD. The sensitivity and specificity of DTP FDG-PET/CT were 20% and 74%, respectively, and for PERCIMT this was 80% and 37%, respectively. Our findings suggest limited efficacy of DTP FDG-PET/CT in distinguishing PsPD from PD in ICI-treated patients with metastatic melanoma. The use of PERCIMT could complement clinical assessment and be incorporated in multidisciplinary team conferences for enhanced decision-making.

Disseminated Primary Uterine Hepatoid Adenocarcinoma with α-Fetoprotein Production Demonstrated on 18F-FDG PET/CT.

We present the 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) findings in a 57-year-old woman with post-menopausal bleeding diagnosed with hepatoid adenocarcinoma (HAC) with a primary tumour in the uterine corpus and a highly elevated level of serum-α-fetoprotein (S-AFP) at presentation. HAC is a variant of adenocarcinoma with hepatic differentiation representing a heterogeneous group of neoplasms that morphologically and immunphenotypically resemble hepatocellular carcinoma (HCC) but are of extrahepatic origin. Microscopically, they are usually poorly differentiated adenocarcinomas proliferating in solid sheets or in a trabecular or cord-like arrangement. Primary uterine HAC is exceedingly rare with a general poor prognosis, and data is sparse and limited to case reports, making the clinical management challenging. Various primary anatomical sites have been reported in the literature, with the stomach being the most common primary site. 18F-FDG PET/CT plays an important role in staging and follow-up in many gynecological malignancies including uterine corpus cancer. To the best of our knowledge, this is the first report describing a primary uterine hepatoid adenocarcinoma with metastases to bone, vagina and lymph nodes on 18F-FDG PET/CT. By utilizing the ability of PET to detect early metabolic changes prior to visible structural changes on conventional imaging, this case illustrates a potential role of 18FDG-PET/CT in the staging of primary endometrial HAC by depicting distant metastasis that is not readily identifiable on CT alone.

18F-FDG PET/CT as a diagnostic tool in patients with extracervical carcinoma of unknown primary site: a literature review.

BACKGROUND: Carcinoma of unknown primary (CUP) represents a heterogeneous group of metastatic malignancies for which no primary tumor site can be identified after extensive diagnostic workup. Failure to identify the primary site may negatively influence patient management. The aim of this review was to evaluate (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) as a diagnostic tool in patients with extracervical CUP. MATERIALS AND METHODS: A comprehensive literature search was performed and four publications were identified (involving 152 patients) evaluating (18)F-FDG PET/CT in CUP patients with extracervical metastases. All studies were retrospective and heterogeneous in inclusion criteria, study design, and diagnostic workup prior to (18)F-FDG PET/CT. RESULTS: (18)F-FDG PET/CT detected the primary tumor in 39.5% of patients with extracervical CUP. The lung was the most commonly detected primary tumor site (∼50%). The pooled estimates of sensitivity, specificity, and accuracy of (18)F-FDG PET/CT in the detection of the primary tumor site were 87%, 88%, and 87.5%, respectively. CONCLUSIONS: The present review of currently available data indicates that (18)F-FDG PET/CT might contribute to the identification of the primary tumor site in extracervical CUP. However, prospective studies with more uniform inclusion criteria are required to evaluate the exact value of this diagnostic tool.

Squamous cell carcinoma of the nasal vestibule 1993-2002: a nationwide retrospective study from DAHANCA.

BACKGROUND: A retrospective nationwide study of cancer of the nasal vestibule was conducted to evaluate classification systems and prognostic factors for treatment outcome. METHODS: Patients treated between 1993 and 2002 at head and neck oncology centers in Denmark were included. RESULTS: The 5-year results were locoregional control 67%, overall survival 50%, cancer-specific survival 74%. Cancer-specific survival according to Wang classification was 83%, 63%, and 39% for T1, T2, T3, respectively (p < .000). Regarding T1 tumors, 5-year locoregional control for surgery, surgery + radiotherapy (RT), or RT was 94%, 87%, or 61%, respectively (p < .000). Fifty-four Gray in 18 fractions was found comparable with 66 Gy in 33 fractions regarding T1 tumors. CONCLUSION: This national survey is the largest series of nasal vestibule cancer ever published. Wang classification is more prognostic and easier to use than the Union Internationale Contre le Cancer 2002. Surgery or hypofractionated RT can be used for T1 lesions, whereas larger lesions should be treated with combined approach.