medwireNews: Nearly a quarter of all cancers diagnosed in the European Union (EU) between 2000 and 2007 were classed as rare, according to updated epidemiologic information from the Information Network on Rare Cancers (RARECAREnet).
The findings were based on data from 94 EU cancer registries, which included nearly 2 million diagnoses of 198 different rare cancers, defined by the RARECARE project as those with an annual incidence of less than six cases per 100,000 people.
Among the 12 major families of rare cancers, which each included several individual cancers, hematologic malignancies, rare cancers of female genital organs and of the digestive tract, and head and neck cancers had the highest overall incidence rates, with group totals ranging from 19 to 28 per 100,000 people per year. Rare skin cancers and noncutaneous melanoma, and embryonal cancers had the lowest incidences, with group totals of 1.22 and 0.34 cases per 100,000, respectively.
Gemma Gatta (Istituto Nazionale dei Tumori, Milan, Italy) and fellow RARECAREnet investigators report in The Lancet Oncology that 24% of all cancers diagnosed in the EU during 2000–2007 were classified as rare.
The overall incidence of rare cancers rose by 0.5% annually over the course of the study, but the researchers note that this was not significantly different from the 0.9% annual increase seen with common cancers during the same period.
They suggest that the increased incidence could be due to improved diagnosis, but also overdiagnosis in the case of thyroid cancer, as well as increased exposure to risk factors such as human papillomavirus.
And although 5-year relative survival among patients with rare cancers increased from 46% overall in 1999–2001 to 49% in 2005–2007, it was still lower than the 63% observed with common cancers.
The largest 5-year relative survival increases were seen for hematologic tumors and sarcomas, including chronic myeloid leukaemia, increasing from 37% to 58%, and soft tissue sarcoma of the viscera, which increased from 35% to 44%. By contrast, cancers categorized as “other myelodysplastic syndromes” had decreased 5-year relative survival, falling from 34% in 1999–2001 to 30% in 2005–2007.
Gatta and team also used data from hospitals in seven European countries, treating around 220,000 rare cancer cases between 2000 and 2007, to study the extent of hospital centralization for rare cancers.
They found that overall, centralization of treatment was generally low but varied widely among the countries, leaving “ample room” for improvement, which could in turn improve survival, they say.
Indeed, subsequent discussions in national meetings “confirmed the need for improving the centralisation of rare cancer treatment in fewer, more specialised hospitals,” Gatta et al write.
They conclude: “Our data offer a starting point to measure the effects of new policies on rare cancers.”
By Laura Cowen
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