**Abstract**

Cancer, the deadliest disease in the world, is taking away the lives of millions of people. The disease and its property of metastasis are still understudied. Various therapies have been discovered to cure this malignancy, but nearly all of them introduce a lot of side effects. Therapies such as radiation, chemotherapy, surgery, etc., are in vogue but are not so economical and approachable for many needy people. Since the nature of cancerous cells is very complex among different individuals, it becomes even more complex to treat them. In modern times, biologically active compounds extracted from plants, weeds, and, most importantly, algae (marine drugs) found in the sea have proved to possess excellent anti-cancer potential. However, the major bottlenecks are the extraction of active substances in ample quantity with high quality. This chapter describes the role of microalgae as anticancer agents. Several aspects of bioactive compounds and challenges linked to microalgae will be discussed. A brief account of nanotechnology and its role in the treatment of cancer in the context of microalgae will be highlighted. The level of algal properties that affect cell proliferation, cell arrest, and apoptosis is elaborated. The current scenario of this investigation is extensively discussed in the study, along with the chemical structure, pros and cons.

**Keywords:** anti-cancer, cancer, microalgae, nanotechnology, bioactive compounds
