CLINICAL, PATHOLOGICAL AND SURVIVAL ANALYSIS IN PATIENTS WITH CANCER OF UNKNOWN PRIMARY SITE: EXPERIENCE OF A LARGE ONCOLOGICAL REFERENCE SERVICE

Background The cancer of unknown primary (CUP) is a heterogeneous group of tumors for which the origin remains unknown despite detailed investigation. Its clinical presentation occurs through metastatic symptoms that may be influenced not only by biological processes of the tumor but also due to regulatory processes in the tumor microenvironment. Faced with a very heterogeneous group of patients, there is a wide variety of clinical presentations and histological subtypes and these differences hinder the accumulation of knowledge with scarce studies on incidence, biology and treatment. Objective To describe the clinical-pathological characteristics and the overall survival of a cohort of patients diagnosed with cancer of unknown primary site. Methods A total of 2585 medical records were retrieved from patients classified as CID-10 C80, diagnosed between 2002 and 2016. After careful selection, 123 CUP cases were identified. Clinical and pathological aspects were collected and registered through the electronic capture tool RedCap (Research Electronic Data Capture). The chi-square test was used for categorical comparisons and Kaplan-Meier for global survival analysis. Results The mean age of the patients was 60 years, ranging from 19 to 88 years, with a predominance of females (56%). Forth-five percent of the cases were smokers and 26% were alcoholics. Fifty-four percent had ECOG 0 or 1 and 46% > = 2, considering 90 cases with this information available. Regarding the histological subtype, the majority of cases were adenocarcinomas (59%), followed by carcinomas (32%) and squamous cell carcinomas (9%). The liver was the predominant metastasis site in 38%, followed by lymph node (26%) and bone (24%). Regarding the treatment, 46% of the patients underwent chemotherapy, 53% of them with the carboplatin and paclitaxel regimen. Median overall survival was 4.8 months. Conclusions Patients are initially diagnosed as CUP due to a lack of better primary site investigation. The majority of “True” CUPs have poor functional performance status and are not eligible to receive chemotherapy, causing a very poor survival despite being treated in a national referral service. It is necessary to improve the reference policies after the diagnosis of CUP as well as the establishment of more assertive diagnostic and treatment protocols.