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Overview of Cancer Therapy

by Bruce A. Chabner, MD, Elizabeth Chabner Thompson, MD, MPH

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).

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