Supplements During Cancer: Help or Hype?
September 14, 2011 – Laura Beil
Unlocking the Mystery of Cancer Stem Cells
September 14, 2011 – Elaine Schattner, MD
Advocates Make Cancer Their Mission
September 14, 2011 – Marc Silver
Choosing an Imaging Test
September 14, 2011 – Charlotte Huff
Do You Need a Cancer Coach?
September 14, 2011 – Jennifer M. Gangloff
Coordinating Care After Cancer
September 14, 2011 – Dawn Dorsey
How to Manage Family Dynamics During Cancer
September 14, 2011 – Jane Hill
Another State Gets Chemo Parity
September 14, 2011 – Taylor Walker
Ford Led Discussion on Breast Cancer
September 14, 2011 – Lindsay Ray
Breast Cancer Drug Scores Win in Prevention
September 14, 2011 – Elizabeth Whittington
Critical Care: A New Nurse Faces Death, Life, and Everything in Between
September 14, 2011 – Kathy LaTour
A Survivorship Resource Map
September 14, 2011 – Elizabeth Whittington
Q & A: Patients Want Coordinated Care
September 14, 2011 – Len Lichtenfeld, MD
San Antonio Breast Cancer Symposium
September 14, 2011 – Lindsay Ray
The Meaning of Stem Cells
September 14, 2011 – Debu Tripathy, MD
Comments from Readers
September 14, 2011
Managing Cancer-Related Diarrhea
September 14, 2011 – Katy Human
Supplement Research in Cancer Lacking
September 14, 2011 – Barrie Cassileth, PhD
Pipeline
September 14, 2011 – Lindsay Ray
Remaining Faithful
September 14, 2011 – Cheryl L. Rice
Açaí Berry’s Effect on Cancer in Question
September 14, 2011 – Jason Roberson
Currently Viewing
What Caused Your Cancer?
September 14, 2011 – Staff Reports
Tell What You’re Taking
September 14, 2011 – Laura Beil
Don’t Believe Everything You Read on Supplement Labels
September 14, 2011 – Laura Beil
Understanding Clinical Trials
September 14, 2011
Checking Out a Charity
September 14, 2011 – Marc Silver
Should You “Just Do It?”
September 14, 2011 – Marc Silver
Previvors Need Expert Guidance, Close Surveillance
September 14, 2011 – Dawn Dorsey
Safety in Numbers
September 14, 2011 – Jane Hill
Flaxseed Doesn't Help With Hot Flashes
September 14, 2011 – Kathy LaTour
From Our Archives: Imaging
September 16, 2011
From Our Archives: Supplements
September 14, 2011
Vitamin D and Folate May Reduce Colon Cancer Risk
September 14, 2011 – Lena Huang
Sleep Problems Impair Childhood Cancer Survivors
September 14, 2011 – Taylor Walker
Cancer Imaging Gets Sophisticated
September 14, 2011 – Susan R. Peck, PhD
From Our Archives: Advocacy
September 14, 2011

What Caused Your Cancer?

Researchers spend years uncovering what can cause cancer and what to do about it.
BY Staff Reports
PUBLISHED September 14, 2011

When the World Health Organization’s International Agency for Research on Cancer (IARC) announced in May that radiofrequency electromagnetic fields, such as those associated with wireless cellphone use, are “possibly carcinogenic to humans,” a cascade of stories warning of the dangers flooded the media, but few provided details of the report

One detail was that the IARC classified radiofrequency electromagnetic fields in Group 2b, which includes other common agents as possible carcinogens, such as coffee, gasoline engine exhaust and pickled vegetables. Group 1 agents, which are classified as “carcinogenic to humans,” include chemicals such as arsenic, but also alcoholic beverages and wood dust.

The IARC’s report and the media’s subsequent coverage illustrate the difficulty of connecting environmental agents to cancer. 

It is generally believed that cancer is the result of “a complex interaction of genetic and environmental factors,” according to the American Society of Clinical Oncology (ASCO). But only a small number of cancers are hereditary, meaning the majority of cancers are caused by factors outside the body or external factors, such as lifestyle choices (smoking, diet, obesity or alcohol), and other environmental causes, such as exposure to radiation, chemicals and viral or bacterial infections that can damage cells and weaken the immune system.

The task of identifying and proving an environmental factor causes cancer is vitally important, evidenced by the fact that some carcinogens that have been identified and verified have resulted in interventions that have become public health policy. Yet that process often requires many years of scientific research, public debate and policy development, with the media simplifying and sensationalizing complicated and often contradictory findings. 

The challenges faced by scientists in studying a suspected carcinogen are particularly difficult, says David Gorski, MD, PhD, managing editor of Science-Based Medicine and a researcher and surgical oncologist at the Barbara Ann Karmanos Cancer Institute in Detroit. 

Gorski references tobacco as an example. The first major study definitively linking smoking to lung cancer was published in the Journal of the American Medical Association in 1950. For the next 14 years, scientists continued to study tobacco, moving through the accepted “levels of evidence” required for scientific conclusions. 

“The point is, you have to look at the totality of the evidence and synthesize it,” Gorski says. “One study never settles anything.” 

At the same time that the scientists were doing their jobs, the issue was being debated in the court of public opinion. It wasn’t until 1964 that Luther Terry, MD, the U.S. Surgeon General, armed with conclusive science, officially declared, “cigarette smoking is causally related to lung cancer in men.” But even though tobacco was officially identified as a carcinogen, it took additional decades of political debate, judicial decisions and advocacy campaigns to finally develop a meaningful public health policy. 

“Everybody wants to know the answer about why they got cancer,” Gorski says. “We look for patterns. But patterns often mislead. Especially when you are looking at small numbers.”

It takes a scientific basis along with large numbers and robust statistical analyses “to figure out what we see and what may have general validity,” he adds.

Editor's Note: In upcoming issues, CURE will help readers understand how researchers identify and investigate suspected cancer-causing agents, build their evidence, test their hypotheses and use their findings to suggest interventions that could influence public policy. 

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