Tirapazamine is primarily used in the field of oncology as a hypoxic cytotoxin, specifically targeting cancer cells that are in low-oxygen (hypoxic) environments. These hypoxic regions are common in solid tumors and are often resistant to conventional radiation therapy and chemotherapy. By selectively killing these oxygen-deprived cells, tirapazamine enhances the effectiveness of radiation treatment. It works by undergoing bioreduction in hypoxic conditions to form a toxic free radical that damages DNA, leading to cell death. This makes it a valuable adjunct in combination therapies, particularly for cancers like head and neck, lung, and cervical cancers, where hypoxia is a significant challenge. Its application is carefully monitored due to potential side effects, but it remains a promising agent in improving cancer treatment outcomes.