Has the cancer-related death trend been changing in Turkey? An evaluation of the period between 2009 and 2019

1Introduction

Non-communicable diseases constitute 71% of deaths worldwide and within this group cancers rank as the second most common cause of mortality [1] . One out of every six deaths in the world and one out of every five deaths in Turkey are related to cancer [23] . GLOBOCAN estimates for 2020 indicated that worldwide there were approximately 20 million new cancer cases and 10 million cancer-related deaths [4] . The estimations for Turkey showed that there were 126,335 cancer-related deaths in 2020 and lung, stomach, pancreas, breast, and colon cancers (excluding lymphoid and hematopoietic cancers) were the cases with the highest mortality [5] .

Some regions in the world have achieved a reduction in cancer-related deaths by progress in prevention, screening, and treatment methods. However, this downward trend was primarily limited only to high-income countries and was not observed in low to middle-income countries [6] . Currently, 70% of cancer-related deaths occur in low to middle-income countries [2] . In a study evaluating premature deaths, it was found that cancer is the most common cause of premature death in 57 of 127 countries, including Turkey. The same research emphasizes that cancer-related deaths will increase and will be the leading cause of premature deaths in most countries by the end of this century [7] .

Accurate evaluation of cancer-related deaths depends on the availability of an effective cancer registry system. Active population-based cancer registry started in Turkey in 1992. There are 14 cancer registry centers available, covering 50.2% of the population [8] . However, Turkey’s data, which is included in the global cancer survival surveillance trends (CONCORD-3) and in GLOBOCAN 2020, were obtained from only nine centers that were qualified to be included. The coverage of these nine centers is 23.4% [59] . The cancer registry in these centers does not include mortality data, which presents another limitation [8] .

Death recording in Turkey has been carried out since 1931. The death records at the national level are collected and published annually by the Turkish Statistical Institute (TURKSTAT). To increase death registration coverage and improve the quality of the data, some modifications were made in 2009. There were two major changes. Firstly, deaths before 2009 were collected only in provinces and districts. However after 2009 deaths from villages were also included in the registration system. Secondly, the classification system for death causes had changed in 2009 and the International Classification of Diseases, Tenth Revision (ICD-10) [10] started to be used since then.