How Cancer Treatment Works: Modalities and Goals

The main modalities of cancer treatment include surgery, radiation therapy, and systemic drug therapies such as chemotherapy, targeted therapy, hormone therapy, and immunotherapy. Treatment intent is often described as curative, meaning aimed at eliminating the cancer, adjuvant, meaning given after primary treatment to reduce recurrence risk, neoadjuvant, meaning given before primary treatment to shrink a tumour, or palliative, meaning focused on controlling disease and relieving symptoms.

Knowing why each part of your treatment plan has been recommended, and what its intended role is, can help you feel more confident discussing your care and asking about expected benefits and side effects. It is reasonable to ask your oncologist to clarify the overall goal of treatment at any point.

Symptoms related to treatment vary depending on the modality used; surgery may cause temporary pain and recovery-related limitations, radiation can cause localised effects such as skin changes or fatigue, and systemic therapies can cause a range of effects depending on the specific drug. Your care team will discuss expected side effects before treatment begins.

Treatment planning follows a confirmed diagnosis and staging, incorporating pathology, imaging, and molecular test results to determine which modalities are appropriate and in what order they should be given. This plan is often developed collaboratively by a multidisciplinary team.

During treatment, monitoring typically includes repeat imaging, blood tests, and physical examinations to assess how well the cancer is responding and to detect any side effects early. Adjustments to the treatment plan may be made based on these results.

The specific combination and order of treatments vary widely by cancer type; for example, many early-stage solid tumours are treated with surgery followed by adjuvant therapy, while some cancers are treated primarily with systemic therapy from the outset. Blood cancers such as leukaemia and lymphoma are typically treated with systemic therapy rather than surgery, given how they spread through the body.

Treatment options span surgery to remove tumours, radiation therapy to target cancer cells with focused energy, and systemic therapies including chemotherapy, targeted therapy, hormone therapy, and immunotherapy, which travel through the bloodstream to treat cancer throughout the body. The specific combination and sequence depend on cancer type, stage, and treatment goals.