Chapter 1 Introduction To Preventing Cancer: Cancer

Content provided by the Faculty of the Harvard Medical School

Chapter 1: Introduction to Preventing Cancer

High-power electrical lines, polluted drinking water, even dry cleaning. When it comes to cancer, nothing seems safe. And when it comes to protecting yourself, nothing seems clear. Is that glass of wine at dinner reducing your risk - or increasing it? Should you be eating more fiber - or cutting back on fat?

Every day seems to bring yet another news story about what causes (or prevents) cancer, raising fear or offering hope. After a while, it's tempting to tune it all out. It's hard to make sense of this changing and sometimes conflicting advice. Is it really possible to prevent cancer? Is enough known about what works and what doesn't to make good decisions?

The short answer is "yes." Based on what researchers have learned so far, cancer is indeed a preventable illness. In fact, experts estimate that at least half of all cancer deaths in the United States could be avoided if more people stopped smoking, ate healthier foods, exercised more, avoided weight gain, protected themselves from common carcinogens (substances that cause cancer), and underwent regular screenings.

That's news to most people. Although researchers have made great progress in understanding and treating cancer, it remains a terrifying disease. And for good reason. First of all, cancer is extremely common. More than 8 million people alive today have had cancer, and another 1.2 million will be diagnosed with some form of the disease this year. About one in three Americans develops a malignant (cancerous) disease in their lifetime - half of all men and a third of all women. Even if you haven't had cancer yourself, you probably know someone who has.

The situation is especially urgent for African Americans, who are more likely to develop cancer - and more likely to die from it - than are individuals of any other American ethnic group. African American men, for instance, are at least 50% more likely to develop prostate cancer than are men of other ethnic backgrounds. And African American women are more likely to die of breast cancer than white women are. There are many reasons for the disparities between African Americans and other ethnic groups, including different dietary habits, heredity, and socioeconomic class, and a lack of access to screening tests and treatment.

Cancer often seems mysterious or even fickle. Nearly everyone knows of someone who smoked, ate nothing but red meat and high-fat food, never exercised - and then outlived all his or her friends. Sadly, there are others who live healthy lives only to develop cancer at young ages. Why should one person be spared and another stricken?

There is no simple answer to this question. Cancer is a complex disease that develops because of the interplay of many factors, including the genes you are born with; your age, diet, and degree of physical activity; and your exposure to carcinogens over time. Cancer is a term that encompasses multiple diseases, and scientists know more about preventing some types than others.

How can you reduce your cancer risk? Some strategies - such as protecting yourself from the sun or not smoking - have been proven through rigorous scientific studies. The evidence for other factors, such as diet and physical activity, is still under investigation. And some factors, such as hormone therapy, are more complicated - increasing risk in some situations, but decreasing it in others. Understanding the leading risk factors and protective strategies - and the best scientific evidence - can help you take steps to lower your cancer risk.

Last updated:	May 01, 2008