Background: Anthraquinones are a possible treatment option for oncological patients due to their anti-cancer properties. Cancer patients often exhaust a plethora of resources that ultimately fail to provide fully curative measures. Alternative treatments are subsequently sought in the hope of finding a therapeutic remedy. Potential regimens include aloe-emodin and its related derivatives. This review therefore summarizes the effects of aloe-emodin and other aloe components in light of their anti-proliferative and anti-carcinogenic properties. Methods: A systematic search was performed in PubMed for aloe-emodin and cancer in humans. Sixty abstracts of in vitro studies were selected and reviewed with subsequent screening of the full text. Thirty-eight articles were summarized. Results: Aloe-emodin possesses multiple anti-proliferative and anti-carcinogenic properties in a host of human cancer cell lines, with often multiple vital pathways affected by the same molecule. The most notable effects include inhibition of cell proliferation, migration, and invasion; cycle arrest; induction of cell death; mitochondrial membrane and redox perturbations; and modulation of immune signaling. The effects of aloe-emodin are not ubiquitous across all cell lines but depend on cell type. Conclusions: On the basis of this systematic review, the multiple consistent effects of aloe-emodin in human-derived cancer cell lines suggest that aloe-emodin is a potential anti-cancer agent that acts on cancer cells in a pleiotropic manner. Relevance for patients: Cancer patients often utilize alternative therapies as a result of suboptimal efficacy of conventional treatments. Aloe-emodin might become a therapeutic option for cancer patients if the basic research is confirmed in clinical trials.