The real additional value of FDG-PET in detecting the occult primary tumour in patients with cervical lymph node metastases of unknown primary tumour

Excerpt

Cervical lymph node metastases may be the first manifestation of cancer. In some patients presenting with a cervical lymph node metastasis, the primary tumour remains elusive after extensive diagnostic work-up. In such cases, the patient is classified as having a so-called unknown primary tumour (UPT). The incidence of UPT ranges from 3 to 7% of all head and neck cancers. The most commonly histological diagnosis is squamous cell carcinoma (SCC). In case of SCC, the following diagnostic procedures are performed: physical head and neck examination at the outpatient clinic, CT or MRI of the head and neck area, X-ray or CT of the chest, and endoscopy under general anaesthesia of the whole upper aerodigestive tract (panendoscopy). During the panendoscopy, directed biopsies are taken from the nasopharynx, the base of the tongue and the tonsils (or tonsillectomy). Unfortunately, the yield of these directed biopsies taken during panendoscopy is low. Consequently, a substantial number of UPTs remains undetected with the conventional diagnostic procedures. In case of UPT, treatment mostly consists of a (modified) radical neck dissection in combination with irradiation of the whole pharyngeal axis. The irradiation of this large surface area aims the elimination of a probably very small (at least undetectable) malignant primary tumour. Unfortunately, this radiation treatment may cause considerable iatrogenic morbidity, e.g. mucositis, xerostomia, mucosal atrophy and even osteoradionecrosis. …