Descriptive epidemiology of sarcomas in Europe: Report from the RARECARE project

Abstract

Sarcomas are a heterogeneous group of malignant neoplasms arising from mesenchymal cells which encompass dozens of histological types and can occur in virtually any anatomic site. They form one of the principal groups of rare cancers in Europe as defined in the RARECARE project. We analysed 45,568 incident cases diagnosed during 1995–2002 and registered by 76 population-based cancer registries. Total crude incidence was 5.6 per 100,000 per year with an estimated 27,908 new cases per year in the EU27 countries, of which 84% were soft tissue sarcomas and 14% were bone sarcomas. Gastrointestinal stromal tumours (GIST) were only widely recognised as an entity in the late 1990s and consequently were under-registered. Their true incidence is believed to be about 1.5 per 100,000. Age-standardised incidence of soft tissue sarcomas ranged from 3.3 per 100,000 in Eastern Europe to 4.7 per 100,000 in Northern Europe. About 280,000 persons were estimated to be alive at the beginning of 2003 with a past diagnosis of sarcoma, of which 83% were soft tissue sarcomas and 16% were bone sarcomas. Five-year relative survival for 2000–2002 by the period was 58% for soft tissue sarcomas and 62% for bone sarcomas. The diversity and rarity of sarcomas combined with the quite large number of people affected by them mean that they provide a classic example of the importance of networking in diagnosis, therapy and research for rare cancers.

Introduction

Sarcomas are a heterogeneous group of malignant neoplasms arising from mesenchymal cells. They can be split up into dozens of histological categories, and they can occur in virtually any anatomic site. This gives rise to a huge number of possible combinations of histology and primary site which are of clinical importance. For example, a well differentiated liposarcoma of a limb has a completely different prognosis, and radically different therapeutic implications, from a histologically identical tumour arising from the retroperitoneum, where surgery is much more challenging. At the same time, a retroperitoneal liposarcoma is clinically different from a leiomyosarcoma of the same region. The complex interplay in sarcomas between anatomic site and histology, both highly relevant from the clinical standpoint, adds to the difficulties that are due to the overall rarity of this family of tumours. For many clinical presentations, medical knowledge and clinical research face major challenges because the numbers are extremely low.

Also from the epidemiological point of view, little information is readily available on patterns of incidence and survival for sarcomas. Fewer than half of all soft tissue sarcomas arise from a connective tissue primary site,¹ and in many primary sites they are outnumbered by carcinomas. Therefore they are not visible in publications in which tumours are grouped according to the International Classification of Diseases topography codes. In Europe in 1995–1999, 5-year relative survival rates of adults with cancers of the bone and cartilage and cancers of soft tissue were 55% and 59% respectively, somewhat higher that the 50% relative survival for all malignant neoplasms.²

The causes of most sarcomas are unknown. Ionising radiation, especially in the form of radiotherapy for a previous cancer, is the only exogenous factor to account for more than a handful of cases.³ Other risk factors include occupational exposure to certain chemicals, including herbicides such as phenoxyacetic acids and wood preservatives containing chlorophenols. Several heritable syndromes are associated with increased risk of sarcomas. Those which account for the largest numbers of cases are probably neurofibromatosis 1 (nerve sheath tumours), heritable retinoblastoma (osteosarcoma and various soft tissue sarcomas) and Li-Fraumeni syndrome (soft tissue sarcomas and osteosarcoma).⁴ Paget disease is a risk factor for osteosarcoma in older adults. In a recent study of the SEER Program, 91% of cases of osteosarcoma in people aged 60 years and over were associated with Paget disease, while 24% of cases in this age group were a second or later primary cancer.⁵

The aim of this paper is to describe incidence, prevalence and survival for sarcomas in Europe, based on a large population-based series of data collected from 89 European cancer registries in the framework of the EC funded project ‘Surveillance of rare cancer in Europe’ (RARECARE).