Cancer is an important leading cause of great psychosocial and economic burden worldwide and about 1.23 million individual annually affected by CRC which is considered as the most common type of cancer ( 9.7 % of overall cancers )and 8 % ( 608,000 case ) died with CRC overall cancer death cases , so it's the fourth most common cause of death among different types of cancer .~There is variability in distribution of cases worldwide , as explained by epidemiological data which showed about 60 % of CRC cases presented in developed countries ( 2 % per year ) while in developing countries there is annual increase in the incidence of CRC cases with proportion occurring among patients with age ≤ 40 years is 2 - 8 percent in western countries while in middle east region its about 15 - 35 percent and the incidence rate is less in female than in male with favorable female gender as a prognostic factor over male .~There are three different risk groups for CRC, these are FAP, hereditary nonpolyposis colon cancer syndrome (lynch syndrome), and genetic mutations that lead to sporadic colon cancer .~The exact cause is unclear but many factors are involved including environmental and genetic . About 24 % of the cases with CRC are due to genetic factors while 75 % of the cases are sporadic and 1 % in patients with pre -existing IBD . Those who immigrates to area with high incidence of CRC from low incidence area may prone to develop CRC which may be related to consumption of red meat and decrease physical activity .~The environmental factors including dietary factors like : Lack of fiber , high-fat diet and exposure of mucosa to high levels of bile acids due to impairment of enterohepatic circulation which leading to form carcinogens from degradation of bile salts while previous cholecystectomy has not been proved to be risk for developing CRC .~Regarding genetic factors, there are several genes among them Tumor suppressor genes (e.g. APC, p53 ) , Oncogenes (e.g Ras) and Mismatch-repair genes (e.g hMSH2 and hMLH1) were identified as contributing to hereditary colorectal cancer .~Here in this study two factors will be discussed with their relation to development of CRC , those factors are ABO blood group , Rh factor and the other one is obesity and as following :~Actually , the first human genetic marker are antigens of the ABO system despite of they are a chemical component on erythrocyte membrane but showing expression on variety of epithelial cells including the mucosa of gastrointestinal tract, that was the leading cause observation studies on any correlation between ABO blood group , Rh with tumor .~From first studies, Aird et al in 1953 who reported a correlation between ABO Rh factor and carcinoma of stomach , also recently a significant association with pancreatic tumor had been reported . In addition to many studies showed a relationship between ABO antigen expression and CRC .~Regarding the obesity , about billion of people are now suffering from obesity worldwide which is considered as one of the strongest factors affecting many health conditions among them some cancers & the prevalence of obesity is rising in many Asian countries including Japan but still lower than western countries .~Many epidemiological studies identified high body mass index as independent risk factor for CRC , some of these studies in western countries showing a significant association between BMI and risk of CRC .
Aim of study: is there possibility of relationship between ABO blood group, Rh & obesity with CRC, that is what we tried to show in this study .