The question of whether cancer can be completely cured is another unknown that perplexes scientists and clinicians. While some cancers, when detected early, can be effectively treated and even eradicated, others tend to recur despite aggressive treatment. The concept of "cure" in cancer is often replaced with "remission," as the long-term absence of cancer does not always equate to a cure. Understanding the biology of residual cancer cells and their potential to cause relapse is a significant focus of current research.