From his student days throughout his whole life, Paul Ehrlich tried hard to obtain ‘chemotherapia specifica’ for the harmless systemic therapy of infectious diseases. Given the poor therapeutic benefit obtained with cytotoxic therapeutic agents and empirical radiopharmaceuticals, so far used only for neoadjuvant and adjuvant treatments of cancer, we have tried to develop Paul Ehrlich’s ‘chemotherapia specifica’ for safe and effective therapy of cancers in cigarette smokers. With the help of sector-field inductively coupled plasma mass spectrometry, we have tried to find the metabolic action of cigarette smoke constituents in the cancerous organ. On the basis of these results we are synthesizing pharmaceuticals and radiopharmaceuticals to purge the tobacco-constituent metabolic products that cause cancer. The purity, stability and chemical nature of the pharmaceuticals and radiopharmaceuticals required for therapy have been studied by chromatography and electrophoresis. The cancer specificity of the therapeutic agent has been examined by the total body distribution of its γ- and β-labelled species in solution. At present, a bladder cancer-specific therapeutic agent is being developed.