Cancer, a devastating large group of diseases, can occur in almost any organ or tissue of the body when cell cycle is disrupted. In the late stages of cancer, the abnormal cells break through normal tissue boundaries and invade other organs (metastasis). According to the World Health Organization (WHO), cancer is considered the second leading cause of death globally, accounting for an estimated 9.6 million deaths, or one in six deaths, in 2018. Lung, prostate, colorectal, stomach and liver cancer are the most common types of cancer in men, whereas breast, colorectal, lung, cervical and thyroid cancer are the most common among women. The Cancer Research UK organization estimates that there will be 27.5 million new cases of cancer each year worldwide by 2040. The cancer therapeutic treatments, currently available, are highly expensive and none of them is completely safe. In particular, these treatments often involve surgical removal and radiation of the biomass in combination with systemic chemotherapy. Although chemotherapy is the most widely used treatment in all types of cancer, may result in recurrence of cancer accompanied with drug resistance as well as severe side effects, making patient's life difficult. Therefore, new non-invasive therapeutic approaches are required to impede the development of cancer.

Cancer chemoprevention generally refers to the pharmacologic intervention with synthetic or naturally occurring chemicals to prevent, inhibit or reverse carcinogenesis or prevent the development of invasive cancer. Up to now, multiple studies have examined the potential anticancer properties of distinct nutritional supplements. These nutritional supplements contain isolated compounds or extracts with bioactivity. As stated by the Office of Dietary Supplements at the NIH, bioactive compounds are defined as constituents in foods or dietary supplements, other than those needed to meet basic human nutritional needs, which are responsible for changes in health status. But what kind of approaches are being utilized to assess the health and safety of bioactive food components? In the context of cancer, the first step is a deep comprehension of health promotion and disease condition. Secondly, the bioactivity of the compound is assessed through appropriate research models, both in vitro and in vivo. Carcinogenicity testing, crucial to assess the safety of a substance, includes short-term in vitro assays, short-term in vivo assays, and the 2-year rodent bioassay.

The cytotoxicity assays utilize cell lines of different origins, in both 2D and 3D systems, and predict the acute toxicity by estimation of LC50 values (lethal concentration for 50% of the cells). In general, these assays are fundamentally colorimetric, involving optical activity of organic dyes (Table 2.5.1).