Gastric Dysplasia: The Padova International Classification
A worldwide-accepted histologic, classification of the gastric carcinomatous and precancerous lesions is a prerequisite for a consistent recording of epidemiologic data and for both developing and evaluating primary and secondary preventive efforts. Different nomenclatures have been proposed for gastric precancerous lesions in eastern countries and in Japan. This article presents a classification of gastric precancerous lesions resulting from an international consensus conference involving pathologists of different countries. Five main diagnostic categories are identified. To allow comparisons with the nomenclature proposed by the Japanese Research Society for Gastric Cancer, each category was also assigned a numeric identification: 1 = normal, 2 = indefinite for dysplasia, 3 = noninvasive neoplasia, 4 = suspicious for invasive cancer, and 5 = cancer. The interobserver reproducibility of the histologic classification was tested in a series of 46 cases. By collapsing benign alterations (categories 1+2) versus noninvasive neoplasia (category 3) versus suspicious for invasive cancer and fully appearing carcinomatous lesions (categories 4+5), the general agreement value was 77.7%, whereas κ coefficient was 0.63. By examining gastric precancerous lesions from diverse populations, the authors agreed that the gastric precancerous process is universal and the differences in nomenclatures are merely semantics. The international Padova classification of the gastric precancerous lesions is submitted to the attention of the international scientific community, which is invited to test and to improve on it.