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Risk: Relative vs. Absolute November 22, 2009

What is the risk of getting cancer? There are two types of risk, absolute and relative.

If you are over 35, try out the breast cancer risk assessment tool at cancer.gov. There are also tools for colorectal cancer and melanoma.

Also from cancer.gov:

Absolute risk is the number of people who will get the disease within a certain time period. Absolute risk gives an actual number of people with that risk factor who will get the condition. You also may see this expressed as, for example, “10 out of 100 people.”

Relative risk compares the chance that a person with a certain risk factor will get cancer to the chance that a person without the same risk factor will get cancer. When you hear that someone is at “high” risk or “low” risk of getting cancer, it is referring to that person’s relative risk.

Relative risk is usually shown as a percent or ratio. The ratio is based around the value of 1. A value above 1 means a higher risk; a value below 1 means a lower risk.

There are different kinds of risk factors, they include genetic (I have a second degree relative with a cancer history-2 generations away), environmental (secondhand smoke exposure and sun), biological (gender, age, race, skin complexion), or behavioral (what I eat and drink, how much exercise I get).

When I was diagnosed with cancer, I had no risk factors. No first degree relatives, (in fact I didn’t know that I had any relatives with cancer until I was asked the family history question for the first time), no second-hand smoke exposure-unless you count flying in the 70’s) , didn’t come from an ethnic group at higher risk etc. Regular readers will recall that I do not have the BRCA 1 or BRCA 2 mutations either. Cancer was a (more…)