title: Age-Dependent Metastatic Spread and Survival: Cancer of Unknown Primary as a Model.
abstract: In order to describe a novel approach for the clinical study of metastases, we provide here age-specific incidence and survival data for cancer of unknown primary (CUP). Metastases in various organs are found at CUP diagnosis, which have implications for prognosis, and we hypothesize similar prognostic implications for metastases found at diagnosis of primary cancers. We identified 33,224 CUP patients from the Swedish Cancer Registry and calculated incidence rates (IRs) for CUP development. Cox proportional hazards regression models were performed to estimate hazard ratios (HRs) for relative survival in CUP patients compared to the general population. In age-group specific analyses, a maximal IR was reached at age 85-89 years, followed by a marked decline to age 90+ (7-fold in men and 3-fold in women). The overall HR for relative survival declined systematically by age. CUP may be applied as an epidemiological age-incidence model for cancer metastases providing evidence in line with autopsy data that the metastatic potential, as shown by the incidence of CUP, appears to weaken markedly at age 85 years, depending on metastatic locations. The relative death rates were highest among young patients, which was probably entirely due to the low death rates in young background population.
authors.affiliation: Division of Molecular Genetic Epidemiology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany.|Center for Primary Health Care Research, Lund University, 20502 Malmö, Sweden.
authors.forename: Kari
authors.initials: K
authors.lastname: Hemminki
authors.affiliation: Department of Medical Oncology, School of Medicine, University of Ioannina, Ioannina, Greece.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Pavlidis
authors.affiliation: Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, University Campus, Ioannina 45110, Greece.|Department of Epidemiology and Biostatistics, The School of Public Health, Imperial College London, London W2 1PG, United Kingdom.
authors.forename: Konstantinos K
authors.initials: KK
authors.lastname: Tsilidis
authors.affiliation: Center for Primary Health Care Research, Lund University, 20502 Malmö, Sweden.|Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, California 94305-5705, USA.
authors.forename: Kristina
authors.initials: K
authors.lastname: Sundquist
authors.affiliation: Center for Primary Health Care Research, Lund University, 20502 Malmö, Sweden.
authors.forename: Jianguang
authors.initials: J
authors.lastname: Ji
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009382:Neoplasms, Unknown Primary / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology*; D011379:Prognosis; D016016:Proportional Hazards Models; D012042:Registries; D016019:Survival Analysis; D013548:Sweden / Q000453:epidemiology