Overview of Cancer Therapy

Treatment of cancer involves destroying malignant cells. Curative treatment requires eliminating all cells capable of causing cancer recurrence in a person's lifetime. The major modalities of therapy are

• Surgery (for local and local-regional disease)

• Radiation therapy (for local and local-regional disease)

• Systemic cancer therapy (for systemic disease)

• Hematopoietic stem cell transplantation

Surgery may be used alone or in combination with other modalities. The size, type, and location of the cancer may determine operability and outcome. Sometimes neoadjuvant chemotherapy is administered to decrease tumor size, to facilitate optimal surgical resection. The presence of metastases typically precludes curative surgery.

Radiation therapy is used to treat many cancers, particularly those that are radiosensitive, are localized, and can be completely encompassed within a radiation field. Radiation therapy is often combined with surgery or systemic therapy.

Systemic cancer treatment modalities include

• Endocrine therapy (for selected hormone-sensitive cancers, eg, prostate, breast, endometrium)

• Immune therapy, including monoclonal antibodies, interferons, biologic response modifiers, tumor vaccines, and cell therapies

• Differentiating agents (eg, retinoids for acute promyelocytic leukemia and isocitrate dehydrogenase-2 (IDH2) inhibitors for acute myeloid leukemia)

• chronic myeloid leukemia)

Often, modalities are combined to create a treatment program that is appropriate for the patient, based on patient and tumor characteristics as well as patient preferences. Various modalities may be used as the primary treatment or before or after the primary treatment. Terminology (1) used to describe types of cancer therapy includes:

• Neoadjuvant therapy: Treatment given before the primary treatment (usually before surgery) to decrease tumor size and thus optimize the primary treatment (eg, make complete surgical resection feasible).

• Primary treatment: The main treatment given for a malignancy after initial diagnosis. It is given with curative intent, if possible.

• Adjuvant therapy: Additional cancer treatment given after the primary treatment to lower the risk that the cancer will recur.

• Palliative care: Specialized medical care for people with serious illnesses focused on providing relief from the symptoms, pain, and stress of a serious illness. The goal is to improve quality of life for both the patient and the family. For cancer, palliative care may include therapies, such as surgery, radiation therapy, or chemotherapy, to remove, decrease size, or slow growth of a tumor that is causing pain (2).

Overall treatment should be coordinated among a radiation oncologist, surgeon, and medical oncologist, where appropriate. Choice of modalities constantly evolves, and numerous controlled research trials continue. When available and appropriate, clinical trial participation should be considered and discussed with patients.

Treatment decisions should weigh the likelihood of adverse effects against the likelihood of benefit; these decisions require frank communication and often the involvement of a multidisciplinary cancer team. Patient preferences for how to live out the end of life (see Advance Directives) should be established early in the course of cancer treatment despite the difficulties of discussing death at such a sensitive time.