Is mass classification in mammograms a solved problem? - A critical review over the last 20 years.

•Mammographic masses classification is dominated by ANN, SVM and KNN.•Grammars and syntactic approaches have not been used so far.•Genetic algorithm was the most used technique to reduce feature dimensionality.•Most of the published papers are database-dependent.•Results are not comparable due to the lack of a common benchmark.