1 Rectal Cancer Epidemiology Miguel Henriques Abreu 1 , Eduarda Matos 2 , Fernando Castro Poças 3 , Rosa Rocha 4 and Jorge Pinto 4 1 Portuguese Institute of Oncology of Porto, Department of Medical Oncology 2 ICBAS, University of Porto, Department of Health Community 3 Porto’s Hospital Centre, Santo Antonio’s Hospital, Department of Gastroenterology 4 Oncological Registry of Vila Nova de Gaia Portugal 1. Introduction Colorectal cancer is the fourth most common cancer in men and the third most common one in women worldwide (Parkin, 2004; Parkin et al., 2005), accounting for approximately 436,000 incident cases and 212,000 deaths in 2008 (Quirke et al., 2011). This cancer has an important economic impact, estimating that in the initial, continuing and last year of life phases of care a total of more than $7 billion were spent (Yabroff et al., 2008). Randomized trials have shown that systematic screening of a target population of suitable age can reduce colorectal cancer by detecting asymptomatic lesions (Center et al., 2009). Although there are differences in the etiologies and epidemiology of colon and rectal cancer (Giovannucci & Wu, 2006), the majority of the studies chose to examine colon and rectum cancers combined. However, a better understanding of these diseases nowadays, shows that these differences have an important impact in their approaches. First of all, the location of the tumours may determines different locations of metastisation. Unlike colon cancers, distal rectal tumours may first metastasize to the lungs because the inferior rectal veins drain into the inferior vena cava rather than into the portal venous system. The histological type can also vary. The vast majority of colorectal tumours are adenocarcinomas but 11-17% are mucinous carcinomas. This type, which has a penchant for the rectum and sigmoid colon, tends to be present at a more advanced stage (Consorti et al., 2000). The carcinoid tumours have a different clinical presentation too, depending on whether they appear in the rectum or in the colon (Marshall & Badnarchuk 1993; Spread et al., 1994). The rectum carcinoids develop at a young age, most of which are less than 2 cm and tend to be indolent. In contrast, colonic carcinoid tumours can be clinically aggressive and often metastise. With a more accurate review, we can see that many habits could influence the development of rectal cancers and not colon cancers. Some studies support the view that family history, as well as the level of physical activity, is a stronger contributor to colon cancer relative to rectal cancer (Wei et al., 2004). The Women’s Health Initiative (a large cohort study) (Paskett et al., 2007) also found a significant link between active cigarette smoking (not passive exposure to cigarette smoke) and rectal but not colon cancer. These differences are important in terms of monitoring and have implications in treatment options, as well. Compared to colon cancers, the sensitivity of CT scan for detection of www.intechopen.com