Cancer is associated to uncontrolled growth of cells. It is the second most common cause of death worldwide. Main treatment consists of surgery, chemotherapy, and radiotherapy. These are procedures with high rates of side effects. Other methods, such as targeted therapy, are under investigation. This method specifically inhibits the growth and proliferation of tumor cells while protecting healthy cells. To date, long non-coding RNAs (lncRNAs) have been implicated in cancer initiation, progression, recurrence, and resistance to therapy. This is due to changes in their expression profile and mutational processes. Thus, concerning tumor prevention, diagnosis, and treatment, lncRNAs are becoming an extremely important point. This chapter highlights the ongoing studies of lncRNAs in the world’s most common cancers, including breast, lung, prostate, colon, stomach, and liver. In the future, this may contribute to the implementation of new means of cancer detection and treatment, with a better prognosis.