Which of the following is a common treatment modality used in oncology?

Chemotherapy is a commonly used treatment modality in oncology because it specifically targets cancer cells to inhibit their growth and division. This form of treatment involves the use of cytotoxic drugs that can be administered systemically to target cancer throughout the body, making it effective for a variety of cancers, particularly for those that have spread beyond their original site. Chemotherapy may also be used in different settings, including as a primary treatment, adjuvant therapy after surgery, or palliative care to alleviate symptoms in advanced disease.

Other options offered, while they may provide supportive care or alternative approaches for some patients, do not hold the same level of efficacy in directly treating cancer. Acupuncture, for example, is often utilized for pain management or side effects associated with cancer and its treatment but does not directly affect cancerous cells. Homeopathy is based on alternative principles and lacks the scientific backing found in evidence-based oncology treatments. Respiratory therapy, while important in managing certain symptoms (particularly related to lung function), is not a primary treatment for cancer itself.