HIV positive patients with locally advanced cervical cancer: Is characterization of FDG PET.CT positive lymph nodes useful?

Objectives: The important role of FDG PET/CT in both the initial staging and re-staging of cancer of the cervix has been demonstrated. Care may be improved by way of differentiating lymph node uptake due to metastases from HIV-reactive adenopathy, particularly in HIV endemic regions. We aim to identify simple characteristics of F-18 FDG PET positive lymph nodes in HIV positive patients with locally advanced cervical cancer.

Methods: Patients with histologically proven locally advanced cervical cancer (FIGO stages IIB to IIIB) underwent FDG PET/CT scans prior to chemo-radiation therapy. The retroviral disease status, as well as CD4 counts of HIV positive patients was serologically obtained prior to commencement of the study. A total of ninety-two consecutive patients were enrolled. HIV negative patients were included to serve as control group. Pattern of uptake was determined using visually assessed symmetry. Standardized Uptake Value (SUV) of PET positive (SUV >2.5) nodes were recorded and compared between HIV positive and negative patients in different nodal regions. CT scoring system based on nodal size on axial images, focal defects and extra-capsular spread was also recorded for lymph node characterization.

Results: Mean age at time of initial staging PET/CT was 49.2 ± 10.4 years, range: 26-70. Forty-six patients (50%) were HIV positive. Overwelming majority (87%) of the patients had asymmetrical FDG uptake in the lymph nodes without difference between HIV status. There was no significant difference in both SUV-max per regional nodal groups and single hottest SUV-max between HIV positive and negative patients (p=0.20 and 0.39, respectively). There was a negative correlation between CD4 counts and single hottest SUV max in HIV positive patients with a tendency to differ (p=0.07). The median CT nodal size is significantly different between HIV positive and negative patients (p = 0.03) for cervical lymph nodes; difference was marginally significant (p=0.05) in the thoracic region. There was however no significant difference in loco-regional nodal groups [lower abdomen and pelvis] (p=0.73), which is usually the predominant sites of nodal disease in advanced cervical cancer. Conclusion: Without definitive histological correlation, FDG PET has a limited utility for differentiating metastases from HIV-reactive adenopathy. The nodal size on CT seems to be a potential parameter to differentiate the possible nature of the visualized lymph nodes in the neck and thoracic regions. The larger the size, the more likely the node would be reactive and most probably due to inflammatory process.