Rucaparib camsylate is primarily used in the treatment of certain types of cancer, particularly ovarian cancer, fallopian tube cancer, and primary peritoneal cancer. It is specifically prescribed for patients who have recurrent cancers with BRCA mutations, as it works by inhibiting the PARP enzyme, which helps repair damaged DNA in cancer cells. By blocking PARP, the drug prevents cancer cells from repairing their DNA, leading to their death. It is often used as a maintenance therapy after patients have responded to platinum-based chemotherapy, helping to delay the progression of the disease. Additionally, it has shown promise in treating other cancers with homologous recombination deficiency (HRD), expanding its potential therapeutic applications.