Immunohistochemical Profile of Mucins in Gastric Carcinoma

Gastric cancer represents the second leading cause of cancer related death (after lung cancer) despite a global decline in both its incidence and mortality since the late half of the 20th century (Kelley & Duggan, 2003; Zheng et al., 2008). This type of cancer continues nowadays to be a major health problem due to the slow decrease in incidence in Asia and its high mortality in the western countries (Roukos et al., 2002). The overall prognosis is reserved, depending on the TNM stage in the moment of diagnosis and somewhat on its histological type (Lauren, 1965). Based on morphological characteristics focused on gland formation and histogenetic background, gastric adenocarcinomas are divided into intestinal and diffuse types using the Lauren classification system (Lauren, 1965), or as differentiated and undifferentiated using the Nakamura classification system (Nakamura et al., 1968). Intestinal-type adenocarcinoma is considered to be equivalent to differentiated adenocarcinoma and the diffuse-type to the undifferentiated adenocarcinoma. These different types of gastric carcinomas express particular biological behaviours. Helicobacter pylori infection leads to the development of chronic atrophic gastritis and intestinal metaplasia (Byrd et al., 1997). Usually the intestinal-type gastric carcinoma arises on the background of intestinal metaplasia (Stemmermann, 1994; Tahara, 1993), and, by contrary, the diffuse-type on the background of gastric mucosa without intestinal metaplasia (Nakamura et al., 1968). The diffuse-type, as classified according to the Lauren system (non-solid type of poorly differentiated adenocarcinoma and the signet-ring cell carcinoma according to a Japanese classification system) (Japanese Gastric Cancer Association, 1996), do not show glandular formation, can be further divided into two subtypes. In the first one, the tumor is predominantly composed of signet-ring cells (>50%) (signet-ring cell carcinomas) and in the other one, the adenocarcinoma contains few signetring cells (<50%) (non-signet ring cell carcinomas). Although these histological types can usually be distinguished using standard stainings, new advances in histochemical and immunohistochemical reactions using gastric and small intestinal cell markers determined emerging of gastric cancer classification into different phenotypes, according to mucin expression (Tatematsu et al., 1990).