Patterns of Cancer – Singapore and the World

By Dr Adeline Seow
Department of Community, Occupational and Family Medicine
National University of Singapore

Cancer is a major disease burden worldwide; every year, approximately 10 million people are diagnosed with the disease, and 6 million die from it ¹.

Overall, the most common cancers globally are cancers of the lung (which make up about 12% of all new cancers), breast (10%) and colorectum (9%). However, there are marked differences between various regions of the world. In developed countries such as the United States and in Europe, a large proportion of cancers are associated with smoking and lifestyle factors; while in developing countries, a significant proportion are associated with chronic infections, such as liver cancer, which is related to the hepatitis B virus, cervical cancer (human papillomavirus) and stomach cancer (Helicobacter pylori)¹ .

I Cancer is a disease associated with aging, and as populations age, the burden of cancer is expected to increase. Hearteningly, there have been some successes in controlling cancer – two examples are the impact on mammographic screening in bringing down breast cancer rates in countries which have screening programmes, and a fall in lung cancer rates in parts of Europe which has been attributed to reduction in smoking among men². In contrast, cancer rates continue to increase in developing countries, aided by changing lifestyle patterns, and it is predicted that by 2020, three-quarters of cancer deaths will occur in the developing world³.

What is the situation in Singapore? Between 1998 and 2002, close to 40,000 new cases were diagnosed among Singapore residents, and the most common types of cancers are shown in Figures 1 and 2. Lung cancer remains the most common cancer among men (accounting for one in five of all new cancers) and breast cancer among women (one in four new cancers). Colorectal cancer, being the second most common site for both men and women, is overall the most common cancer diagnosed in Singapore, followed closely by lung cancer. It is also important to take note of cancers which are less common now, but are showing signs of increasing in our population, and have increased in other parts of the world. Prostate cancer in men, and lymphomas in both men and women, are among the sites with the sharpest rates of increase in recent years⁴.

Research into the causes of human cancer has made significant progress in the past decade. At the same time, the World Health Organization estimates that it is possible to prevent at least one-third of new cases each year through better application of existing knowledge¹, including reducing tobacco use and modifying harmful lifestyles. Understanding the patterns of cancer also contributes to planning for resources to help cancer patients and to provide screening and treatment that will reduce the burden of this disease throughout the world.

¹ Stewart BW and Kleihues P (Eds): World Cancer Report. IARCPress. Lyon 2003
² Quinn MJ. Cancer trends in the United States – a view from Europe (Editorial). J Natl Cancer Inst 2003;95:1258-61.
³ Wilson CM, Tobin S, Young RC. The exploding worldwide cancer burden: the impact of cancer on women. Int J Gynecol Cancer 2004;14:1-11.
⁴ Seow A, Koh WP, Chia KS, Shi LM, Lee HP, Shanmugaratnam K. Trends in Cancer Incidence in Singapore 1968-2002. Singapore Cancer Registry Report No. 6, Singapore, 2004.