Autophagy is an ancient cell survival pathway that is induced by metabolic stress and that helps prevent bioenergetic failure. This pathway has emerged as a promising new target in cancer treatment, where agents that inhibit autophagic degradation have efficacy in preventing cancer and in treating resistant disease when combined with conventional chemotherapeutics, which generally activate the pathway. However, agents that specifically target the autophagy pathway are currently lacking, and monitoring the effects of therapeutics on the autophagy pathway raises several challenges. Here we review the potential roles of the autophagy pathway in tumor progression and in maintenance of the malignant state, and introduce novel methods that we have developed that allow one to monitor autophagic activity ex vivo and in vivo.