Cancer Incidence in Oman (1996–2015)

Abstract

Cancer remains a major public health problem worldwide. In 2018, the International Agency for Research on Cancer (IARC) estimated that over 18 million new cases of cancer were diagnosed and nearly 10 million people lost their lives to this group of diseases.1 Yet, cancer is not invincible and can be abated through effective cancer control programs that implement evidence-based strategies for prevention, early detection, treatment, palliation, and making the best use of available resources.2 Such programs aim to reduce cancer incidence, its associated morbidity and mortality, and improve quality of life.3 However, this requires careful planning, continuous monitoring and evaluation of processes, and output and outcome indicators to assess whether program objectives are achieved. One of the most common methods to obtain such indicators is through cancer surveillance systems in the form of populationbased cancer registries that systematically collect, analyze, and report cancer data of a well-defined geographical area. In this issue, Al-Lawati and colleagues provide evidence of the cancer burden in Omanis over the past two decades (1996–2015).4 This publication comes 24 years after the Oman National Cancer Registry (ONCR) was transformed from a hospitalbased registry (documenting only cases diagnosed and histologically confirmed in tertiary hospitals in the Muscat governorate) to a population-based registry covering the entire country and including all cancers diagnosed by multiple modalities and all medical disciplines. Data of the ONCR were assessed by the IARC and were included in volume VIII and IX of Cancer Incidence in Five Continents.5–7 Currently, this registry covers nearly five million Omanis and expatriates with three-trained cancer registrars and a medical supervisor. It also provides an important database4 for policy makers in setting priorities for the prevention and control of cancer in Oman as well as being a tool for monitoring its incidence trends over time. The reported incidence data4 are limited to Omani nationals and exclude expatriates working in Oman due to their skewed distribution (mostly young males coming from diverse geographical regions worldwide making it complex to define a denominator to calculate incidence). From 1996 to 2015, over 21 000 cases of cancer were registered among Omanis, with an average of 1050 cases/year. The frequency of cases among both genders was similar (51% men vs. 49% women). The average annual age-standardized incidence rates (ASR) reported were slightly higher in men than women (105.2 vs. 96.3 cases per 100 000, respectively). These rates are half the rates reported globally (218.6 and 182.6 per 100 000 in males and females, respectively)8 mostly due to the young structure of the Omani population with only 3–4.3% aged above 65 years. Similar low rates were also reported from neighboring Gulf Corporation Council (GCC) countries (Bahrain 105.2 per 100 000, Qatar 112.5 per 100 000, Saudi Arabia 88.7 per 100 000, Kuwait 121.8 per 100 000, and the UAE 112.5 per 100 000 population).9 The 20-year trends data show breast and thyroid cancers to be the most common malignancies affecting Omani women (accounting for 21.2% and 10.0% of all cases, respectively).4 A similar pattern was seen in all GCC states between 1998 and 2007.10 editorial Oman Medical Journal [2019], Vol. 34, No. 4: 271-273