**1. Introduction**

Cancer, the second leading cause of death worldwide, is severely affecting the health of our society and the circumstances do not appear to improve [1]. The continuous and exponential cell division amplifies the tumor and leads to metastatic cancer [2]. Several drugs are designed to treat the disease. Therefore, the cost touches the sky, it requires that the cell lines which are isolated from the biopsy are found to be different varieties that require personalized medication [3]. The standard chemotherapy comprises radiation, medication, and drugs, that after some time show the side effects [3, 4]. Besides this, the ideology used is that the target is to destroy the cell line which is killing the natural defense cells as well as the other cells which are captured by these tumor cells and leading to proliferation [5]. Sometimes, the cancer is cured completely but after years, it comes back, and this stage is secondary metastasis [6].

Nature might have the solution to this problem as well [7]. The microalgae, which can be easily cultivated and can tolerate extreme environmental conditions, prove to be suitable for various purposes [4, 8]. The extensive variety of microalgae can open the doors for various chemical and biological interactions, which could lead to treatment pathways [4]. The unique compounds found in the microalgae are derived and experimented with cancer cell lines [9]. This treatment can be effective and has a high biological activity for the purpose [10]. The microalgae can be effortlessly cultured and nurtured in bioreactors. From this, enormous biomass is obtained, which signifies it is renewable for various purposes [11]. It is still inadequately investigated for drug innovations [12]. They utilize the energy from the sun and fix carbon dioxide, which amplifies the greenhouse gas outcomes and eliminates nitrogen and phosphorus [13]. The activity depends on the variant of replicas' nurturing conditions. It is a maker of stable isotopes 13C, 15N, and 2H [13]. The entity has many roles to play in pharmaceuticals, cosmetics, nutraceuticals, aquaculture, etc. [14].

The components of great importance found in them are lipids, proteins, carbohydrates, and nucleic acids, supplemented by pigments, vitamins, minerals, and polysaccharides [13]. The biologically active compounds found in the variants are for example acetylic acids, β-carotene, agar, agarose, alginate, PUFAs, vitamin B, lutein, etc. [15]. For instance, sterols are utilized to cure cardiovascular diseases. Most face, skin, and sun protection cosmetics incorporate microalgae into their composition [14]. For example, *Tetraselcuis suecica, which belongs to the Chlorophyceae,* gives 74g PUFA per kg. It is effective against lung adenocarcinoma. A549 is an alveolar base epithelial cell and H460 is a lung tumor cell line with an operative quantity of 5-μg μL−1 [16, 17]. *Chlorella vulgaris* arrests cell proliferation and metastasis of lines H1299, which are non-small lung cancer cells extracted from lymph nodes, A549 adenocarcinoma alveolar base cells, and H1437 which is the same caused by p53 mutations. It is treated which affects the cell arrest at 200 μg mL−1 [17–19]. The cost of biomass processing is high due to its poorly researched situation. It can be further augmented to obtain maximum benefit for various purposes. The exploitation of resources is yet to be done. Proper protocols and ethical issues must be retained [12]. Nature should not be hampered by treatments, industrial requirements, and research work [6]. It possesses antimicrobial, antifungal, antiviral, anti-HIV, anti-neurological, and anticancer qualities [20]. It also has its part in environmental issues like wastewater management and greenhouse effects. The component here is natural, safe, and renewable which is the biggest aspect to be researched, it invites the various departments of biological sciences, and the motif of fighting the cancer is attracted towards it [17].
