Page 30 Complete Your CE Test Online - Click Here and listed on a single web page ( along with background information about carcinogens. But to find specifics about a suspect carcinogen (study summaries, routes of exposure, etc.) professionals will still want to see the more detailed reports on the substance or exposure on the IARC or NTP websites [32]. Evidence-based practice: Find reliable, well-researched information and full background research reports about known and suspected carcinogens online at the U.S. National Toxicology Program (NTP) and the International Agency for Research on Cancer (IARC), at and http://, respectively [161]. For substances that cannot be found listed as carcinogens on either of these lists, the first step is to look for other names for the substance. Sometimes the chemical name listed in the reports is not exactly the same one found in other sources. Search engines can often help find information on reliable science websites that list multiple synonyms and common names for chemicals. Having a list like this can help find research-based information for patients with possible carcinogen exposure, or help them to find information for themselves. The U.S. National Cancer Institute (NCI) has information about what causes cancer. See prevention/risk/substances/carcinogens. The NCI has links to the specialty groups like the U.S. National Toxicology Program (NTP) and the International Agency for Research on Cancer (IARC), which is part of the World Health Organization. There is also access to good research in websites like PubMed, http://www.ncbi.nlm.nih. gov/pubmed/, (see section “Resources for Nurses” or “Disproven Carcinogens and Other Cancer Myths”). Age Advancing age is the most important risk factor for cancer overall, and for many individual cancer types (Figure 1). According to the most recent statistical data, the median age of a cancer diagnosis is 66 years. This means that half of cancer cases occur in people below this age and half in people above this age. One-quarter of new cancer cases are diagnosed in people aged 65 to 74 [137]. A similar pattern is seen for many common types of cancer. For example, the median age at diagnosis is 61 years for breast cancer, 68 years for colorectal cancer, 70 years for lung cancer, and 66 years for prostate cancer [137]. Of course, cancer can occur at any age. For example, bone cancer is most frequently diagnosed among people under age 20, with more than 25% of cases occurring in this age group. And 10% of leukemias are diagnosed in children and adolescents under 20 years of age, whereas only 1% of cancer overall is diagnosed in that age group. Some types of cancer, such as neuroblastoma, are more common in children or adolescents than in adults [137]. Inherited genetic changes There are a number of genetic syndromes which increase cancer risk that can be inherited. A few of the more common ones are discussed here. BRCA1, BRCA2, and breast cancer BRCA1 and BRCA2 are human genes that produce tumor suppressor proteins. When either of these genes is mutated, DNA damage may not be repaired properly. Given that inherited mutations are present in every cell of the body, there are many cells available that will be more likely to develop additional genetic alterations that can lead to cancer. Certain inherited mutations in BRCA1 and/or BRCA2 increase the risk of breast and ovarian cancers, and they are linked to increased risks of some other types of cancer. Breast and ovarian cancers in women with BRCA1 and BRCA2 mutations tend to develop at younger ages than in those without these mutations [140]. A woman’s lifetime risk of developing breast and/or Figure 1. Percent of New Cancers by Age Group: All Cancer Sites. SEER 18 2007-2011, adapted from NCI. All Races, Both Sexes [137].