Can the clinical course of cancer be influenced by non-antineoplastic drugs?

Laboratory and anecdotal clinical evidence suggests that some common non-antineoplastic drugs may affect the course of cancer. The authors present two cases that appear to be consistent with such a possibility: that of a 63-year-old woman in whom a high-grade angiosarcoma of the forehead improved after discontinuation of lithium therapy and then progressed rapidly when treatment with carbamazepine was started, and that of a 74-year-old woman with metastatic adenocarcinoma of the colon that regressed when self-treatment with a nonprescription decongestant preparation containing antihistamine was discontinued. The authors suggest that epidemiologic studies are needed to investigate a possible association between non-antineoplastic drugs and the clinical course of cancer and that consideration should be given to discontinuing all nonessential medications for patients with cancer.