The unknown biology of the unknown primary tumour: a literature review

Abstract

The unknown primary tumour (UPT) is an intriguing clinical phenomenon found in approximately 5% of all newly diagnosed patients with cancer. It is unclear whether UPT forms a distinct biological entity with specific genetic and phenotypic characteristics, or whether it is merely a clinical presentation of metastases in patients in whom the primary tumour cannot be detected and does not result in any visible clinical signs. Understanding the basic biology of UPT may shed light on this issue and, moreover, may have a direct impact on clinical care. A review of the literature revealed only a limited number of publications describing the genetic and phenotypic features of UPT, most of which focus only on the potential of these markers to predict prognosis. The question as to whether the biology of UPT is different from tumours of known primaries therefore remains unanswered. Further insight into the molecular mechanisms underlying the oncogenesis of UPT, e.g. by applying newly available DNA and gene profiling microarray techniques, will be necessary to understand its specific biology and to develop more effective treatments.

Multiple Metastatic Small Cell Carcinoma of Unknown Primary Diagnosed on Inguinal Node Biopsy

“…In some instances, although the metastatic pattern is often unpredictable, the site of primary origin can be found during lifetime or autopsy. Generally it is a small nodule often localized in the lungs or in the bilio-pancreatic tract [11]. Since the unknown primary mass can be located anywhere in the body, a cross-sectional whole-body imaging modality is the proper method to search for it.…”

Liver metastases with unknown primary focus in the first application: evaluation of 52 cases

“…[1] Adenokarsinom metastazların-da primer oda¤ın bulunması prognozu belirgin de¤itirmezken, nöroendokrin kökenli tümör-lerde ise yaam süresi, yaam kalitesi ve direkt tedavi giriimlerine katkısı açısından oldukça önemlidir. [7] Riihimäki ve ark.…”

“…Primer oda¤ı bulabilmek için radyolojik görün-tülemeler, histopatolojik yöntemler, monoklonal antikor panelleri, kanser hücrelerinin genetik ve fenotipik karakterlerini belirlemeye yönelik moleküler teknikler kullanılabilmekte-dir. [1,9] Sonuç olarak, tedaviye iyi yanıt veren tümörleri atlamamak için karaci¤er metastazlı hastalarda biyopsi yapmak faydalı olacaktır.…”

“…[1] Tüm malignitelerin yaklaık %5-10'unu olutururlar. [2] Primeri bilinmeyen metastatik tümörlerin yaklaık %33'ünü karaci¤er metastazları olutur ve prognozu kötüdür.…”

Clinical implication of 18F-FDG PET/CT in carcinoma of unknown primary

“…Its prognosis is poor with a median survival time of only 4 months [5]. If we succeed in detecting the primary tumor, thus converting the unknown primary tumor into a defined tumor disease with a primary tumor and metastases, it may lead to more specific treatment planning and improving the outcome [6,7]. Less than 20% of patients with CUP have a primary site of their cancer identified even antemortem.…”