Cancer in Kuwait: Magnitude of The Problem

Transcription

1 Abstract Cancer in Kuwait: Magnitude of The Problem A. Elbasmi 1, A. Al-Asfour 1, Y. Al-Nesf 2, A. Al-Awadi 1 1 Kuwait Cancer Control Center, Ministry of Heath, State of Kuwait 2 Ministry of Heath, State of Kuwait Cancer registry data obtained from the Kuwait Cancer Registry at Kuwait Cancer Control Center (KCCC) of Ministry of Health, State of Kuwait. The data covers the years 1974 to Aim of this study To estimate the magnitude of the cancer problem in Kuwait over the period Materials and methods Age-adjusted incidence rates (ASR) with standard error (se) and 95% confidence intervals (95% CI) of age-standardized rates were estimated. Statistical significance was assessed by examining the standardized rate ratio (SRR). Results It was noted that by following the Cancer registry data there was a trend of increase in adjusted rates among both males and females. Looking into specific cancers it was noticed that comparing the ASR of colorectal cancer among Kuwaiti males, it increased by about 5 folds over the last 33 years and ranked the 1st most frequent site on the years Prostate cancer incidence increased by 3 folds (14.5 cases /100,000 person year) and ranked the 4th most frequent site among Kuwaiti males. Overview Kuwait Recent statistics demonstrated that Kuwait s total population at the end of December 2007 stood at 3,328,136. Of that figure, 1,038,598 (31.2%) were Kuwaiti citizens while the remaining 2,289,538 (68.8%) were expatriates (1). The total number of females numbered 1,245,020 Correspondence: Dr. A. Elbasmi, Kuwait Cancer Control Center, Ministry of Kuwait, State of Kuwait. elbasmy@yahoo.com 44 The incidence of Non Hodgkin s Lymphoma (NHL) and leukemia had increased by 1.5 to 2 folds over the same period. The rise of lung cancer incidence declined to similar rates compared to that observed in the early 70s and 80s. For Kuwaiti females breast cancer had the highest incidence among Kuwaiti population (15 cases /100,000 person year), it increased by 3 folds (50 cases /100,000 person year) over the last 33 years. The incidence of colorectal cancer increased by about 4 folds; (13 cases /100,000 person year). NHL and leukemia increased by folds over the same studied duration. Meanwhile Thyroid cancer increased by one fold. Conclusion & Recommendations Some of the differences in cancer rates over the last 33 years are likely to be attributable to the variation in exposure to specific etiologic factors that are caused by differences in lifestyle and habits, such as dietary, physical activity and obesity. Further research with a view to understanding these changes in cancer incidence is warranted. There is a need for an interventional prevention programs that vigorously involve, diet, anti-smoking and physical activity among both sexes. Key words Kuwait cancer registry, trend, cancer incidence while males numbered 2,083,116 out of the total population. Female citizens outnumbered male citizens. There are 529,839 female and 508,759 male Kuwaitis. Expatriate males stood at 1,574,357 while expatriate females numbered 715,181. Kuwait Cancer Registry (KCR) The Kuwait Cancer Registry was established in 1971, and in operation ever since. KCR is a full member of the International Association of Cancer Registries (IACR). KCR data quality

2 meets the standard of IACR. KCR is the first Arab and Gulf country to have its results accepted and published in "Cancer in Five Continents" since its 5th edition in 1990 (2). 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) (2) as well as mortality data from the Vital and Health Statistics Division, MOH, Kuwait. Aim To estimate the magnitude of the cancer problem in Kuwait over the period through: 1. Assessment of cancer incidence among Kuwaiti population over the last 33 years. 2. Find out the cancer situation in Kuwait compared to other countries. Materials and Methods Study Design The cancer assessment was conducted using existing incidence data from KCR. The software programs CanReg4 and Microsoft Excel were used for data base construction analysis and drawing. The standardized rate ratio (SRR), and confidence intervals were calculated using Microsoft Excel. Methods The age-standardized incidence was calculated for every individual year using the population at risk reported by the Ministry of Planning, Statistics and Census Sector state of Kuwait (1). KCR receives about 700 new Kuwaiti cancer patients annually. In an attempt to overcome the small number of patients an average figures for ASR included the periods , , , and were used for comparison excluding years of and 1992 due to under registration. Male and female Kuwaiti population was analyzed separately. KCR data coded based on the "International Classification of Diseases for Oncology, Third Edition" codes (3). Duplicate cases were eliminated. Patients with more than one different primary site were counted as G. J. O. Issue 8, 2010 multiple cases. Date of diagnosis was used as date of onset of disease. Calculation of rates The age-specific rate: Is the number of new cancer cases occurring in people in a given age group divided by the population in that age group in a given period expressed per 100,000 populations. Incidence rates are expressed in terms of annual rates (i.e., per year), and when data is grouped over 5 years the denominator is converted to an estimate of person per years. Population at risk (denominator): The study present the KCR incidence rates for Kuwaiti population only. The denominator for such rate is obtained from generally approximated mid-year population (or the average of the population at the beginning and end of the year or period), obtained from the Ministry of Planning, Statistics and Census Sector, State of Kuwait (1). Age-standardization-direct method (ASR): An age-standardized rate is the theoretical rate, which would have occurred if the observed agespecific rates applied in a reference population. KCR uses the World Standard Population (4). Standard error (se) of age standardized rates-direct method: This method was used as a measure of precision of the estimated rate. It was also used to calculate confidence intervals for the rate. Confidence Intervals provide a measure of the stability of a calculated incidence rate. The study uses a 95% CI incidence rate. Calculation of the 95% CI follows the methods described in IARC monograph Cancer registration: Principles and methods (5). Standardized rate ratio (SRR): SRR represents the relative risk of disease in population 1 compared to population 2. Standardized rate ratio statistical significance was calculated (5). 45

3 Cancer in Kuwait: Magnitude of the Problem, Elbasmi A, et. al ASR/ population 95%CI UCL LCL ASR Fig. 1 : Trend of Cancer Age Standardized Incidence Rate (ASR) world /100,000 with 95% confidence intervals among kuwaiti Males from year 1974 to year ASR / populations 95% CI UCL LCL ASR Fig. 2 : Trend of Cancer Age Standardiezed Incidence Rate (ASR) world /100,000 with 95% confidence intervals among Kuwaiti Females from year 1974 to year UCL=Upper confident limit LCL=Lower confident limit ASR=Age standardized incidence rate Results Trends of Cancer Incidence in Kuwait: By the end of December 2007, the Kuwait cancer registry recorded a total number of 37,340 cancer cases, 14,471 of them were Kuwaiti. The age standardized incidence rates /100,000 populations with 95% confidence interval over the last 33 years for males and females are shown in Figure 1 and 2 respectively. In 2007 the ASR 95% CI was ( ) cases/100,000 populations and ( ) cases/100,000 populations for Kuwaiti males and females respectively. Standardized 46 Rate Ratio (SRR) is considered significant if the values do not include one, and not significant if the values cover one. Accordingly male 2007 ASR was of no statistical significance when compared to annual cancer ASR. On the other hand, 2007 ASR was significant when compared with ASR of year 1990 and this was due to lack of registration in that Mean while the 2007 female ASR was significant when compared to years , 1990 and 1991 ASRs. This is related to under registration in these time periods (Table 1). (Figure 3) shows the average figures for ASR

4 G. J. O. Issue 8, 2010 included for the periods , , , and Agestandardized rate of males (95% CI) person year was 91.7 per ( ), ( ), ( ), ( ) and ( ) person year, respectively. The ASR (95% CI) for females for the same periods was 97.1 ( ), ASIR person/year male female Years Male Female SRR ǂ VS 2007 SRR ǂ VS , ,0.81* , , , , , , , , , , , , , , , , ,0.88* 0.61,0.90* , ,0.95* , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,1.28 ǂ SRR= Standardized Rate Ratio. * = Significant Table 1 : Comparison of the Kuwait Cancer Registry ASR from with ASR 2007 in both Kuwaiti males and females. 47 Fig. 3 : Time Trend of Age Standardized Incidence Rates of Kuwaiti population ASIR / 100,000 person year Lung NHL Prostate Colorectal Leukemia Prostate Colorectal Leukemia Fig. 4 : Time Trend of Age Standardized Incidance Rates For the Five Most Common Cancer Sites-Kuwait Males, ( ), ( ) ( ) and ( ) respectively. Further analysis explored the changes in trend of the most common frequent cancer sites. (Figure 4) shows that the incidence of colorectal cancer among Kuwaiti males increased by about five folds from 3 cases /100,000 person year in early 70 and 80s to 15 cases/100,000 person year and ranked the first most frequent site year 2007 (Table 2) (10). Prostate cancer increased by three folds from 6.4 cases /100,000-person year to 14.5 cases /100,000-person year and ranked the fourth most frequent site among Kuwaiti males. The incidence of NHL increased by one and half folds from 6.9 cases /100,000-person year to 10.6 cases /100,000-person year. Leukemia ASR increased by two folds from 3.9 cases /100,000- person year to 8 cases /100,000-person year over the last 33 years. The rise of lung cancer incidence declined to a similar rate compared to that observed in the early 70s ASR 12.9 and 13.6 cases /100,000-person year respectively. Breast cancer had the highest incidence among Kuwaiti females. The ASR was 15 cases /100,000 person year increased by three folds to 50 cases /100,000 person year over the last 33 years The Lung NHL

5 Cancer in Kuwait: Magnitude of the Problem, Elbasmi A, et. al. Males (N=273) Females (N=420) Site % ASIR Site % ASIR Colorectal Breast Non Hodgkin s lymphoma Colorectal Leukemia Thyroid Prostate Ovary Trachea, bronchus &lung Corpus uteri Bladder leukemia Brain & Nervous system Hodgkin s Disease Hodgkin s Disease Non Hodgkin s lymphoma Liver Cervix Pancreas Pancreas ASIR = Age Standardized Incidence Rate / 100,000 Table 2 : Leading Cancer Sites among Kuwaiti Nationals, 2007 incidence of colorectal cancer increased by about four folds from 3 cases/100,000 person year to 13 cases /100,000 person year. ASR of NHL increased by two folds from 3.3 cases /100,000- person year to 5.5 cases /100,000-person year, and the ASR of leukemia increased by two and half folds from 1.7 cases /100,000-person year to 5.2 cases /100,000-person year. The incidence of thyroid cancer increased by one fold from 5.9 cases /100,000-person year to 8.3 cases /100,000- person year (Figure 5). Cancer in Gulf Center for Cancer Registration (GCCR) 6 : The Kuwait cancer incidence was lower than that found in Qatar & Bahrain, but higher than that of Oman, UAE and KSA. Incidence among females was higher than males. The most frequent sites of cancer among GCC countries were breast, colorectal, NHL, leukemia and thyroid. The incidence of Kuwaiti female breast cancer stood third after Bahrain and Qatar. Kuwait ranked second in the incidence of colorectal cancer 48 ASR / 100,000 person year Breast Thyroid Thyroid NHL NHL Colorectal Leukemia Leukemia Fig. 5 :Time Trend of Standardized Incidence Rates for the Five Most common Cancer Sites-kuwaiti Females, for both males and females after Qatar. The incidence of NHL in Kuwait ranked second after Qatar. Kuwait leukemia incidence among males and females ranked third following Bahrain and Qatar. The incidence of thyroid cancer among Kuwaiti females as well as Kuwaiti males ranked second after Qatar (Table 3). Kuwait and the world: Breast Colorectal Cancer ASR in thirteen cancer registries of different countries was compared to Kuwaiti s ASR of Countries were ranked in

6 G. J. O. Issue 8, 2010 All Breast Colorectal NHL Leukemia Thyroid Qatar Bahrain Kuwait Oman KSA UAE Gulf Center for Cancer Registration, (2009) 6 Table 3 : Summary of the five most common cancer sites in the GCC states descending order according to their overall cancer incidences. Cancer incidence in Kuwait was lower than that of western and other Arab countries except for Algeria as Kuwait ranked the 12th. The incidence of thyroid cancer is high compared to the selected countries; Kuwait ranked fifth of 13. The incidence among females was 5 times more than that reported for males. Kuwait stood the 8th among selected countries in female breast cancer incidence rate. Colorectal cancer ranked Kuwait the 9th with nearly equal incidence for male and female. Leukemia and NHL ranked the 10th with higher incidence among males. Males NHL ASR was three times higher than those reported by females (Table 4). Discussion The time trend of age-standardized incidence rates for all cancers in Kuwait appears to be slightly rising comparing year-to-year incidence, but when combining the data to 5 years duration, the incidence increased significantly, with higher female incidence specially observed since late 80s. However, the increased incidence among Kuwaiti population is still lower than that reported by developed countries (2-7). In Kuwaiti men, the most common cancer sites were colorectal, Non Hodgkin s lymphoma, leukemia, lung and prostate. Colorectal cancer overtook leukemia and Non Hodgkin s lymphoma and stood the first most common cancer site in 2007 (10), Prostate cancer has also become increasingly common. The increased 49 incidence of lung cancer during and may be related to over registration. However, further research is needed to explore this point. Remarkably, its incidence in was found to be similar to that reported in the 70s which indicates that more efforts are needed in the prospect of smoking control. In Kuwaiti women, cancer of breast, colorectal, thyroid, ovary and corpus uteri were the leading types of cancer. According to the analysis provided by IARC, with the ASR of Kuwaiti females malignancies (all sites but skin), breast and colorectal had increased significantly (2). In general, the increased cancer incidence in both Kuwaiti males and females could be due to increased awareness and the availability of more advanced diagnostic techniques. It may also may be related to the changes in socio-economic status e.g. ageing of the population, urbanization and adoption of western lifestyles. As a result of which, there is high prevalence of obesity (BMI 30) among Kuwaiti Males (36%) and females (48%). Sixty-five percent of Kuwaiti populations are not physically active. The prevalence of inadequate intake of fruits and vegetables (less than 5 servings / day) is (81%); prevalence of smoking is (42%) and (4%) for males and females respectively (11). The mentioned risk factors for chronic non-communicable diseases in Kuwait were reported by a large scale survey study conducted by WHO and the GCC in conjunction with the Ministry of Health in Kuwait. Those factors largely explain the

7 Cancer in Kuwait: Magnitude of the Problem, Elbasmi A, et. al. All Breast Colorectal NHL Leukemia Thyroid USA, SEER: Black ( ) USA, SEER: White ( ) UK, England ( ) Victoria, Australia (2005) Canada ( ) Japan, Hiroshima ( ) Norway ( ) Colombia ( ) China, Shanghai ( ) Egypt ( ) Benghazi (2004) Kuwait (2007) Algeria ( ) Table 4: Age standardized incidence rates (ASIR world) / 100,000 in Kuwait compared to cancer registries of different countries. development of the most common types of cancer in Kuwait which are breast and colorectal. Conclusion and Recommendation In conclusion, the Kuwaiti population has an excess cancer rate for a number of sites. A constant finding is the excess of breast cancer in Kuwaiti females. Some of the differences in cancer rates over the last 33 years are likely to be attributable to the variation in exposure to specific etiologic 50 factors that are caused by differences in lifestyle and habits, such as dietary, physical activity and obesity. Further research with a view to understanding these changes in cancer incidence is warranted. There is a need for an interventional prevention programs that vigorously involve diet, anti-smoking and physical activity among both sexes.

8 1. Health, Kuwait, edition 44, (2007): Health vital statistics division, department of statistics & medical records, Ministry of health, state of Kuwait. 2. Curado. M. P., Edwards, B., Shin. H.R., Storm. H., Ferlay. J., Heanue. M. and Boyle. P., eds (2007): Cancer Incidence in Five Continents, Vol. IX IARC Scientific Publications No. 160, Lyon, IARC. 3. WHO (2000) International Classification of Diseases for Oncology, Third edition, Geneva, World Health Organization. 4. Doll, R., Payne, P. & Waterhouse, J. A. H. (1966): Cancer Incidence in Five Continents, Volume 1, Geneva, UICC; Berlin, Springer. 5. Boyle P. and Parkin DM. (1991): Statistical methods for registries. In: Jensen OM, Parkin DM, MacLennan R, Muir CS, Skeet RG, editors. Cancer registration: Principles and Methods. IARC Scientific Publications No. 95. Lyon: International Agency for Research on Cancer;. p References G. J. O. Issue 8, Eight-Year cancer incidence among nationals of GCC states , June (2009). 7. The Cancer Council Victoria Epidemiology Center (2008): CANSTAT: Cancer in Victoria Freedman, L.S., Edwards, B.K., Ries, L.A.G., & Young, J.L. (Eds.). (2006): Cancer incidence in four member countries (Cyprus, Egypt, Israel, and Jordan) of the Middle East Cancer Consortium (MECC) compared with US SEER. Retrieved October 3, 2007, from 9. Cancer incidence and mortality in eastern Libya (2004): report from Benghazi Cancer Registry. 10. Elbasmi A., and Al- Asfour A., (2010): Kuwait cancer registry annual report-2007, Kuwait cancer control center, Ministry of health; Kuwait. 11. Al-Nesf Y., Kamel M., El-Shazly M., Makboul G., Sadek A., Elsayed A., El Farargy A., (2008): Eastern Mediterranean Approach for control of Non Communicable diseases, Survey of Risk Factors for Chronic Non Communicable Diseases, State of Kuwait. 51