[Triple and quadruple cancers (author's transl)]

The authors report two cases of multiple cancers (three and four) and precise the criterions of multiplicity of cancers, their frequency and their localizations. The factors incriminated in multiple carcinogenesis, often not well known and complicated, are also studied, such as family ground, age, blood groups, hormones, viruses, immunologic deficiencies and some carcinogenic drugs. Moreover, the actual progress in therapy, leading to the healing of the first tumor, may favour the secondary supervening of one or more cancers, as the survival is longer.