Pertuzumab is primarily used in the treatment of HER2-positive breast cancer. It is often administered in combination with other drugs like trastuzumab and docetaxel, particularly for patients with metastatic or locally recurrent unresectable breast cancer. This combination therapy helps to block the HER2 receptor more effectively, slowing down the growth and spread of cancer cells. Pertuzumab is also used in neoadjuvant settings, meaning it is given before surgery to shrink tumors and improve surgical outcomes. Additionally, it has shown efficacy in adjuvant therapy, reducing the risk of cancer recurrence after initial treatment. Its targeted approach makes it a valuable option in personalized cancer treatment regimens.