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• Principles of Cancer Therapy
4

Curing cancer requires eliminating all cancer cells. The major modalities of therapy are

• Surgery and radiation therapy (for local and local-regional disease)
• Chemotherapy (for systemic disease)

Other important methods include

• Hormonal therapy (for selected cancers, eg, prostate, breast, endometrium)
• Immunotherapy (monoclonal antibodies, interferons, and other biologic response modifiers and tumor vaccines—see Tumor Immunology: Immunotherapy of Cancer)
• Differentiating agents such as retinoids
• Targeted agents that exploit the growing knowledge of cellular and molecular biology

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.

Various terms are used to describe the response to treatment (see Table 1: Principles of Cancer Therapy: Defining Response to Cancer Treatment). The disease-free interval often serves as an indicator of cure and varies with cancer type. For example, lung, colon, bladder, and testicular cancers are usually cured if a 5-yr disease-free interval occurs. However, breast cancer may recur even after 5 yr; thus a 10-yr disease-free interval is more indicative of cure.

Table 1
Defining Response to Cancer Treatment Term Definition Cure Permanent absence of symptoms or signs of a disease, although patients who appear to be cured may still have viable tumor cells that eventually cause relapse Complete remission (complete response) Disappearance of clinical evidence of disease Partial response > 50% reduction in size of tumor mass or masses, sometimes leading to significant palliation and prolongation of life, but with inevitable regrowth of the tumor Stable disease Neither improvement nor worsening Disease-free survival (disease-free interval) Interval between disappearance of the tumor and relapse Duration of response Time from response to time of overt progression Survival time Time from diagnosis to death

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

Last full review/revision July 2009 by Bruce A. Chabner, MD; Elizabeth Chabner Thompson, MD, MPH

Content last modified July 2009