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  • Cancer A-Z

    Whether you or someone you love has cancer, knowing what to expect can help you cope. Here you'll find in-depth information on specific cancer types – including risk factors, early detection, diagnosis, and treatment options.

    • Explore Cancer A-Z
    • Breast Cancer
    • Colon and Rectal Cancer
    • Lung Cancer
    • Prostate Cancer
    • Skin Cancer
    • All Cancer Types

    Featured Topics

    • Skin Cancer Gallery
    • Non-cancerous Breast Conditions
    • Cancer in Children
    • Rare Cancers, Sub-types, and Pre-cancers

    Related Resources

    • Cancer Glossary
    • Cancer News
    • For Health Care Professionals
  • Risk, Prevention, & Screening

    You can help reduce your risk of cancer by making healthy choices like eating right, staying active and not smoking. It’s also important to follow recommended screening guidelines, which can help detect certain cancers early.

    • Explore Risk, Prevention, & Screening
    • Find Cancer Early
    • Stay Away From Tobacco
    • Eat Healthy & Get Active
    • Be Safe in the Sun
    • Protect Against HPV
    • What Causes Cancer?
    • Cancer Facts

    Featured Topics

    • Screening Guidelines by Age
    • Genetics & Cancer
    • Sun Safety Videos
    • BMI Calculator

    Related Resources

    • Signs & Symptoms of Cancer
    • Tests to Diagnose Cancer
    • Cancer Prevention News
  • Treatment & Survivorship

    Whether you want to learn about treatment options, get advice on coping with side effects, or have questions about health insurance, we’re here to help. 

    • Explore Treatment & Survivorship
    • Understanding Your Diagnosis
    • Treatment & Side Effects
    • Survivorship
    • Financial & Insurance Matters
    • Children & Cancer
    • For Caregivers & Family
    • Nearing the End of Life

    Featured Topics

    • Clinical Trials
    • When Natural Disasters Strike
    • Personal Health Manager
    • Caregiver Guide

    Related Resources

    • ACS Bookstore
    • Cancer Survivors Network
    • Stories of Hope
  • Programs & Services

    The American Cancer Society offers programs and services to help you during and after cancer treatment. Below are some of the resources we provide. We can also help you find other free or low-cost resources available.

    • Explore Patient Programs and Services
    • Lodging During Treatment
    • Rides to Treatment

    Get Support

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    • Schedule a Video Chat

    More Resources

    • Find a Resource
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  • Our Research

    What does it take to outsmart cancer? Research. We’ve invested more than $5 billion in cancer research since 1946, all to find more – and better – treatments, uncover factors that may cause cancer, and improve cancer patients’ quality of life.

    • Explore Our Research
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  • Get Involved

    We couldn’t do what we do without our volunteers and donors. Together, we’re making a difference – and you can, too. Become a volunteer, make a tax-deductible donation, or participate in a fundraising event to help us save lives.

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  • About Us

    At the American Cancer Society, we’re on a mission to free the world from cancer. Until we do, we’ll be funding and conducting research, sharing expert information, supporting patients, and spreading the word about prevention. All so you can live longer — and better.

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  • Risk, Prevention, & Screening

What Causes Cancer?

Cancer is a complex group of diseases with many possible causes. In this section you can learn more about the known and possible causes of cancer, as well as general information about carcinogens and how genetics play a role in cancer.

Read more

Understanding the Causes of Cancer

There are a lot of rumors and myths about cancer that make it hard to know what’s true. Here are answers to some of the questions you may have. You'll also learn how potential carcinogens are tested and classified, and find a list of known and probable carcinogens.

  • Common Questions About Causes of Cancer
  • Is Cancer Contagious?
  • Determining if Something Is a Carcinogen
  • Cancer Clusters
  • How to Interpret News About Cancer Causes
  • Cancer Warning Labels Based on California's Proposition 65
  • Known and Probable Human Carcinogens
Read more

Genetics and Cancer

Some types of cancer run in certain families, but most cancers are not clearly linked to the genes we inherit from our parents. Learn about the complex links between genes and cancer, as well as genetic testing and how it is used.

  • Genes and Cancer
  • Family Cancer Syndromes
  • Genetic Testing for Cancer Risk
Read more

Tobacco and Cancer

Get information on cigarette, cigar, and other types of tobacco use, and learn how it can affect your health, including your risk of cancer.

  • Harmful Chemicals in Tobacco Products
  • Is Any Type of Tobacco Product Safe?
Read more

Diet and Physical Activity and Cancer

Get the facts on how diet, physical activity, excess body weight, and alcohol use may affect your risk of cancer.

  • Diet and Physical Activity: What’s the Cancer Connection?
  • Body Weight and Cancer Risk
  • Alcohol Use and Cancer
Read more

Infections and Cancer

In the United States and other developed countries, a small portion of cancers are thought to be linked to infections. Learn more about some of the infectious agents linked to cancer in this section.

  • Infections that Can Lead to Cancer
  • HIV Infection and AIDS
  • HPV (Human Papillomavirus)
Read more

Radiation and Cancer

Learn about the different types of radiation and how exposure to them might affect cancer risk.

  • X-rays and Gamma Rays
  • Radon
  • Ultraviolet (UV) Radiation
  • Radiofrequency (RF) Radiation
  • Power Lines, Electrical Devices and Extremely Low Frequency Radiation
  • Cellular (Cell) Phones
  • Cell Phone Towers
Read more

Chemicals and Cancer

Get the facts about some known, possible, and unlikely environmental causes of cancer. 

  • Antiperspirants
  • Asbestos
  • Aspartame
  • Hair Dyes
  • Perfluorooctanoic Acid (PFOA), Teflon, and Related Chemicals
  • Talcum Powder
  • Water Fluoridation
  • View All
Read more

Medical Treatments and Cancer

Medical tests and treatments can be an important part of getting and staying healthy. But some types of tests and treatments may actually increase a person's risk of developing cancer. Get the facts about possible links between certain medical procedures and cancer.

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