Childhood cancer incidence and survival

The following blog post is written by researcher Keiu Paapsi who recently published a paper on childhood cancer incidence and survival in Estonia. Here she gives an overview of the current situation in Estonia compared to other countries and discusses why childhood cancer needs more public attention.

Before going to childhood cancer numbers in Estonia, let me give you a brief overview of some terms which you often come across with reading cancer related articles or leaflets or what you might hear from your doctor.

Speaking about cancer we most often hear two terms: incidence and survival. The first one describes new cases that are diagnosed in a specific time interval (usually a calendar year) given per 100 000 people. The second one – survival – is a more complex term. In statistics, survival can be used to evaluate current treatment options and health care system overall, but among patients and doctors it is a way to describe the prognosis of the disease to patients and their families. Survival is mainly given as 5-year survival and that describes the percentage of patients still alive 5 years after the initial diagnosis. But we need to keep in mind that the latter one is still a statistical figure which combines both patients – the ones with a better and the ones with a worse outcome of that number.

Since childhood cancer is so rare (some types have only 2-3 cases per year, other occur even more seldom), it is more common to analyze incidence and survival in bigger cohorts. Thus many different International projects are conducted. One of the biggest in Europe, where Estonia participates, is called EUROCARE. EUROCARE analyzes childhood cancer data, giving us the opportunity to compare our results with other countries (for example with other Nordic countries that have a similar healthcare system and treatment protocols). Even though Estonian healthcare has improved a lot since the 90s, we still saw from the results of EUROCARE-5 (Gatta et al., 2014) that survival rates in Estonia lag behind the European average. So, in 2014 we conducted a study that set out to analyze childhood cancer data in Estonia in 2000–2011, in order to clarify the underlying reasons for it.

Results of the study showed that about 35 children under the age of 18 are diagnosed with cancer every year in Estonia. The overall incidence rate in children aged 0–14 years in 2000–2011 was 14.9 cases per 100 000. Cancers were more frequently diagnosed in boys (55%) and in the age group 0–4 (43%) years. The most commonly diagnosed sites were leukaemias (31%), CNS (central nervous system) tumours (29%) and lymphomas (11%). Childhood cancer incidence in Estonia is comparable to that of our neighbouring countries. For example incidence rates for leukaemia for the same period were 3.6 and 4.0/100 000 for boys and girls, respectively, which were only slightly lower than the respective rates in Finland (5.6 and 5.2) and Sweden (5.4 and 4.2) (Forman et al., 2014).

5-year survival rate in 2000–2011 in children aged 0–14 years for all sites combined was 76%. Although now close to the European average for 2000–2007 (78%) (Gatta et al., 2014), it still lags behind the recent rates observed for Denmark (86%) (Schrøder et al., 2016), Austria (86%) (Karim-Kos et al., 2016) or France (82%) (Lacoura et al., 2014). 5-year survival estimates for most commonly diagnosed sites were 90.8% for lymphomas, 70.9% for CNS tumours and 81.5% for leukaemias. Survival estimates for Estonian children diagnosed with lymphomas and CNS tumours were close to those found in Switzerland (Schindler et al., 2017) or Austria (Karim-Kos et al., 2016), but considerably lower estimates were found for leukaemias. 5-year survival for lymphoid leukaemia (86%) and for myeloid leukaemia (56%) were far below those observed in several other countries (Lacoura et al., 2014; Karim-Kos et al., 2016; Schindler et al., 2017). Poorer prognosis for 5-year survival were found for neuroblastomas (56.7%), soft tissue sarcomas (56.2%) and germ cell and gonadal tumours (43.6%). No survival rate could be calculated for hepatic tumours, since all patients died already during the first year after diagnosis. On the other hand, survival rates for retinoblastomas and carcinomas were estimated to be 100%.

As the result of the study we learned that to some extent our lag in survival rates were caused by under-reporting of cases to the cancer registry (statistical error). But at the same time we need to acknowledge ourselves that there are still many problems that need to be faced. In Estonia, we still don’t have paediatric oncology residency program, we still have problems with treatment availability (some medications are needed too seldom to be kept available consistently), we still lack experience when it comes to diagnosing very rare types of cancers, and so on. And that is the reason why childhood cancer needs more public attention. We already have excellent doctors and scientists who keep this topic close to their hearts, but we need the attention of policy makers and the public. Even if just to raise awareness of the early signs and symptoms of childhood cancer.

Results of the study can be seen in more detail here.

References:

Forman D, Bray F, Brewster DH, Gombe Mbalawa C, Kohler B, Piñeros M, et al. (2014). Cancer incidence in five continents, vol X IARC scientific publication no 164. Lyon: International Agency for Research on Cancer.

Gatta G, Botta L, Rossi S, Aareleid T, Bielska-Lasota M, Clavel J, et al. (2014). Childhood cancer survival in Europe 1999–2007: results of EUROCARE-5 – a population-based study. Lancet Oncol 15:35–47.

Karim-Kos HE, Hackl M, Mann G, Urban C, Woehrer A, Slavc I, et al. (2016). Trends in incidence, survival and mortality of childhood and adolescent cancer in Austria, 1994–2011. Cancer Epidemiol 42:72–81.

Lacoura B, Goujonb S, Guissoua S, Guyot-Goubinb A, Desméeb S, Désandesa E, et al. (2014). Childhood cancer survival in France, 2000–2008. Eur J Cancer Prev 23:449–457.

Schrøder H, Rechnitzer C, Wehner PS, Rosthøj S, Møller JK, Lausen B, et al. (2016). Danish childhood cancer registry. Clin Epidemiol 8:461–464.

Schindler M, Belle FN, Grotzer MA, von der Weid NX, Kuehni CE, et al. (2017). Childhood cancer survival in Switzerland (1976–2013): time-trends and predictors. Int J Cancer 140:62–74.