Cancer Health Effects

Cancer—a group of diseases characterized by uncontrolled growth of abnormal cells—affects almost everyone's life, either directly or indirectly. About 1 out of 2 men and 1 out of 3 women living in the United States will develop cancer at some point in their lifetimes.

An important step in preventing cancer is to identify its causes. Sources of exposure that could be targeted for cancer prevention include:

  • Occupational exposures to industrial chemicals
  • Pollution, such as chemicals, particles, or mixtures found in air or water
  • Chemicals found in household products or indoor air
  • Certain medical treatments
  • Infections
  • Exposures resulting from lifestyle choices, such as tobacco smoking

Report on Carcinogens: Identifying Carcinogens

The Report on Carcinogens (RoC) is a congressionally mandated, science-based, public health report that provides a cumulative list of known or reasonably anticipated human carcinogens. The report contains a short synopsis of key studies on cancer, exposure data, and regulations to limit exposure for each listed substance, agent, mixture, or exposure circumstance (collectively referred to as substances).

NTP prepares the report on behalf of the Secretary of Health and Human Services. Substances are listed in the report following a multi-step process, with several opportunities for scientific and public input and using established listing criteria.

RoC Monographs: Assessing Cancer Hazards

To determine whether a substance should be listed in the Report on Carcinogens, an extensive assessment of publicly available, relevant cancer studies is conducted, which is captured in an RoC monograph. RoC monographs became a part of the review process in 2012; prior to that, background documents were prepared.

These literature-based assessments use systematic review methods that integrate the relevant evidence across many different types of studies to reach conclusions about whether a substance is a cancer hazard. Studies include:

  • Cancer epidemiology studies in humans
  • Cancer studies in experimental animals
  • Studies of cancer mechanisms and other relevant data, such as how the substance is processed in the body

The evidence is then assessed to determine if it fulfills the RoC listing criteria for one of two categories: "known to be a human carcinogen" or "reasonably anticipated to be a human carcinogen."