Profile of Lung Cancer in Kuwait

BACKGROUND
Lung cancer is the most frequent cancer in males and the fourth most frequent site in females, worldwide. This study is the first to explore the profile of lung cancer in Kuwait.


MATERIALS AND METHODS
Cases of primary lung cancer (Kuwaiti) in Kuwait cancer Registry (KCR) were grouped in 4 periods (10 years each) from 1970-2009. Epidemiological measures; age standardized incidence rate (ASIR) with 95% confidence intervals (CI), Standardized rate ratio (SRR) and Cumulative risk and Forecasting to year 2020-2029 used for analysis.


RESULTS
Between years, 2000-2009 lung cancer ranked the 4th and the 9th most frequent cancer in males and females respectively. M:F ratio 1:3. Mean age at diagnosis (95%CI) was 65.2 (63.9-66.4) years. The estimated risk of developing lung cancer before the age of 75 years in males is 1.8% (1/56), and 0.6 (1/167) in females. The ASIR for male cases was 11.7, 17.1, 17.0, 14.0 cases/100,000 population in the seventies, eighties, nineties and in 2000-2009 respectively. Female ASIR was 2.3, 8.4, 5.1, 4.4 cases/100,000 population in the same duration. Lung cancer is the leading cause cancer death in males 168 (14.2%) and the fifth cause of death due to cancer in females accounting for 6.1% of all cancer deaths. The ASMR (95%CI) was 8.1 (6.6-10.0) deaths/100,000 population and 2.8 (1.3-4.3) deaths/100,000 population in males and females respectively. The estimated Mortality to incidence Ratio was 0.6.


CONCLUSIONS
The incidence of lung cancer between years 2000-2009 is not different from that reported in the seventies. KCR is expecting the number of lung cancer cases to increase.


Introduction
Lung cancer is the most frequent cancer in the world.The number of new cases worldwide is 1.6 million accounting for 12.7% of all new cancer cases in the world.The number of deaths due to lung cancer estimated to be 1.83 million representing 18.2% of all deaths due to cancer worldwide (GLOBOCAN, 2008).
It is the most frequent cancer in males estimated incidence is 1.1 million cases 16.5% of all new male cancer cases (GLOBOCAN, 2008); however, it is less frequent in females 516,000 cases accounting for 8.5% of all new female cancer cases worldwide and ranked the fourth most frequent site and the second cause of death due to cancer after breast.
North America has the highest incidence as lung cancer ranked the second most frequent cancer in females.The lowest incidence estimated in Middle Africa where it ranked the 15th most frequent cancer.
It is the seventh most common cancer site in the gulf area representing about 4.8% from all cancers (Ten-Years Cancer Incidence among Nationals of the GCC States 1998-2007, 2011).This study is the first to explore the profile of lung cancer in Kuwait.

Materials and Methods
Kuwait cancer registry (KCR) is a population based registry covering about three million Kuwaiti and non-Kuwaiti residents in Kuwait.KCR established and in operation since 1971.It is a full member of the International Association of Cancer Registries (IACR).It is the first Arab and Gulf country to have its results accepted and published in "Cancer in Five Continents" since its fifth edition in 1990.(Curado et al., 2007).Notification of cancer is compulsory by ministerial regulations.The registry collects information on malignant neoplasm according to the recommendations of the International Agency for Research on Cancer (IARC) (Curado et al., 2007), as well as mortality data from the Vital and Health Statistics Division, of MOH, Kuwait Health, Kuwait, (2010).Lung cancer cases included in this study defined as C33-C34 according to the international classification of disease for oncology third edition (Fritz et al., 2000).The study included all primary lung cancer cases (Kuwaiti) registered in Kuwait cancer registry grouped in 4 periods: Seventies (1970-1979), Eighties (1980-1989), Nineties (1990Nineties ( -1999Nineties ( ) and 2000Nineties ( -2009. .Calculation of age standardized incidence rate (ASIR) with 95% confidence intervals (CI), Standardized rate ratio (SRR) and Cumulative risk calculated according to the methods described in (Boniol and Heanue, 2007) Forecasting to year 2020-2029 calculated on Excel 2010.

Results and Discussion
Between January 2000 and December 2009, 15,714 new cancer cases added to Kuwait cancer registry database accounting for 35% of the registry data: 7,793 cases occurred among Kuwaiti (M:F ratio 1:1.35).
In the absence of other causes of death, a Kuwaiti male has an estimated 1.8% cumulative risk of developing lung cancer before the age of 75 years (one case for every 56 Kuwaiti males).The estimated risk for Kuwaiti female is 0.6 (one case in every 167 Kuwaiti female).Out of the collected cases, 813 were lung cancer, accounting to 5.2% of registry data in the same duration.About half (404 cases) were Kuwaitis.Lung cancer ranked the fourth and the ninth most frequent cancer in Kuwaiti males and females accounting to 8.8% and 2.5% of all new cancer cases diagnosed between 2000-2009; respectively.Seventy three percent of cases were males.Male to female ratio was three to one.Mean age at diagnosis (95%CI) was 65.2 (63.9-66.4)years.Seventy four percent of cases aged 60+ years.Three quarter (75%) of cases were living in Hawalli, Capital, and Farwaniya.Forty five percent of the lesions detected in the right lung.Histology of primary was the basis of diagnosis in 46.3% of cases while diagnosis confirmed by cytology in 35.4% of cases.Non-small cell carcinoma (M-8046/3) accounted to 36.4% of cases, while small cell carcinoma, NOS (M-8041/3) accounted onetenth (10.9%) of cases.Grade III (poorly differentiated) tumors observed in 11.9% of cases.One-third (30.4%) of cases presented with regional metastatic disease.Distant metastasis was the first presentation in 37.4% of the cases.Twenty eight percent of cases were of unknown/NA extent of disease.Eighteen percent of cases submitted to surgery, forty-nine percent received chemotherapy and about 38% received radiotherapy.
When the 95%CI was taken into consideration, the calculated rates showed an overlapping pattern indicating a non-statistical significant variation Figure 1.Furthermore statistical significance was not proved in pair-wise comparison of rates as the SRR is close to 1.0 Table 2.
Between year 2020-2029, Kuwait cancer registry is expecting the number of cases to reach 425 and 161 for males and females respectively.However, the ASIR shows slight increase from 14.0 to 17.33 cases per 100,000 population in males and 4.4 to 6.1 per 100,000 population in females (Figure 2).

Deaths due to lung cancer
Between years 2000-2009, 2,247 deaths were due to cancer among Kuwaiti people, of which lung cancer was responsible for 233 deaths.It is the leading cause of death due to cancer in males 168 (14.2%) deaths on the other hand it ranked the fifth cause of death due to cancer in Kuwaiti DOI:http://dx.doi.org/10.7314/APJCP.2013.14.10.6181Profile of Lung Cancer in Kuwait females accounting for 6.1% of all deaths due to cancer.
The ASMR (95%CI) was 8.1 (6.6-10.0)deaths/100,000 population and 2.8 (1.3-4.3)deaths/100,000 population in males and females respectively.The estimated mortality to incidence ratio was 0.6.Based on 2000-2009 data, the risk of dying from lung cancer by the age of 74 years was 1.1% for males and 0.7% for females Table 3.

Lung cancer in Kuwait and world
The estimated age-standardized incidence rate for the World was 22.9, which is lower than that estimated for Kuwait, 9.4 new cases per 100,000 people.The highest age-standardized incidence rate estimated was for Hungary, French Polynesia and United States of America 52.0, 43.6 and 42.1 new cases per 100,000 people respectively.The lowest estimated was for The Cape Verde, Niger, and Malawi 1.1, 0.9 and 0.7 respectively (GLOBOCAN, 2008).The incidence of lung cancer ranked Kuwait the third after Bahrain 19.7 new cases per 100,000 people and Qatar 11.9 new cases per 100,000 people (GLOBOCAN, 2008).
In 39 years from 1970 to 2009, the mid-year population of Kuwaiti people doubled from 347,396 to reach 1,102,485 individuals respectively.In the survey study conducted by the, ministry of health, Gulf council cooperation and WHO (Al-Nesf et al., 2008), to explore the risk factors of chronic non-communicable diseases in Kuwaiti people; the overall prevalence of daily smoking was 20.6%.It is one of the highest smoking prevalence reported compared to other countries in the area e.g.7% in Oman, 10.8% in Iran, 29.6% in Tunisia, 14.8% in Iraq, 12.8% in United Arab Emirates 29% Jordan and 23.7% in Yemen as reported by (World Health Organization, 2011).Average age (years) of initiation of smoking (95%CI) was 18.5 (17.9-19.1)years.The most important environmental risk factor positively associated for smoking initiation were the history of smoking among siblings with a relative risk of 1.4 (Sugathan et al., 1998).Average duration (years) of smoking (95%CI) was 13.8 (12.9-14.7).Education, type of residence, and history of smoking among family members and friends found to be independently associated with the risk of initiation (Moody et al., 1998).The average amount of cigarettes/day (95%CI) was 22.1 (20.6-23.6)compared to 23.7, 15.9, and 13.5 of cigarettes/day in Jordan, Egypt and Qatar respectively (World Health Organization, 2011).
The high prevalence of smoking among Kuwaiti people and the high measures of smoking index can explain the increasing number of lung cancer cases.The rapid growth of population can partially explain the slow increase of ASIR.
In conclusion, Lung cancer is the first cause of death due to cancer among Kuwaiti males.The smoking indices in Kuwaiti population are high.The incidence of lung cancer in year 2000-2009 is not different from that reported in the seventies.Kuwait cancer registry is expecting the number of lung cancer cases to increase.As about 90% of lung cancer could be prevented through action and awareness.Effective health promotion measures should be applied to combat the threatening risk.