Overview of Cancer Therapy

By Bruce A. Chabner, MD, Professor of Medicine;Clinical Director, Harvard Medical School;Massachusetts General Hospital Cancer Center ; Elizabeth Chabner Thompson, MD, MPH, Private Practice, New York Group for Plastic Surgery

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Principles of Cancer Therapy
Overview of Cancer Therapy
Modalities of Cancer Therapy
Management of Adverse Effects of Cancer Therapy
Cachexia in Cancer
Incurable Cancer

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

Surgery (for local and local-regional disease)
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 Immunotherapy of Cancer)
Differentiating drugs such as retinoids
Targeted drugs 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 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, large cell lymphomas, and testicular cancers are usually cured if a 5-yr disease-free interval occurs. However, breast and prostate cancers may recur long after 5 yr, an event defining tumor dormancy (now a major area of research); thus, a 10-yr disease-free interval is more indicative of cure.

Defining Response to Cancer Treatment

Term	Definition
Cure	Long-term 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
Progression-free survival	Time from initiation of treatment to time of overt progression in a surviving patient
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 Advance Directives).

Last full review/revision July 2013 by Bruce A. Chabner, MD; Elizabeth Chabner Thompson, MD, MPH