The top magazines in the U.S. typically shortchange readers when it comes to articles on prostate and colon cancer screening, according to researchers.

Their study of 18 top-selling magazines found that of 36 “in-depth” articles on prostate or colon cancer, only 28 percent gave readers full information on the benefits and downsides of screening for the diseases.

The shortcoming is important, according to the study authors, because for people who don’t discuss these issues with a doctor, magazine articles “may provide the only opportunity to correct misperception” about screening.

The researchers, led by Dr. Mira L. Katz of Ohio State University in Columbus, report the findings in the Journal of General Internal Medicine.

The study included the three top-selling magazines in each of six categories, including publications aimed at women, men and African Americans. The researchers identified 36 in-depth features on prostate or colon cancer written between 1996 and 2001, and they analyzed the articles for information on screening.

With colon cancer, screening is considered vital to catching the disease in the early stages. Some options include fecal occult blood testing, which detects blood in the stool; sigmoidoscopy, in which a slender tube is inserted to view the lower portion of the colon; and colonoscopy, which probes further into the colon.

Each procedure has its pros and cons. Fecal occult blood testing, for example, often yields false-positive results, but negative results do not necessarily mean a person is cancer-free. Sigmoidoscopy can miss tumors as well, because it does not give a view of the upper portion of the colon.

Limits aside, experts say most men and women should begin some form of colon cancer screening at age 50, while those with risk factors, such as a history of polyps or chronic inflammatory bowel disease, should talk with their doctors about earlier screening.

Prostate cancer screening, on the other hand, is controversial because it is not yet clear that the practice saves lives. Blood tests for prostate-specific antigen (PSA) can be used to detect prostate cancer, but there are limits and downsides. PSA elevations may indicate cancer, but there are a number of other conditions, such as benign prostate enlargement or infection, in which PSA may rise.

In addition, prostate cancer often grows slowly. PSA testing may lead to treatment of tumors that would never have progressed far, exposing men to unnecessary side effects, such as impotence and incontinence.

The full complexity of such issues was captured only in a minority of the magazine features Katz and her colleagues reviewed. For example, only 46 percent mentioned the uncertainties surrounding prostate cancer screening.

It seemed male readers were likely to be least informed, the researchers found, as nearly two thirds of the articles on colon cancer screening were published in women’s magazines.

The lack of full information in these articles, Katz and her colleagues conclude, “may help explain the low awareness of the importance of colon cancer screening and the lack of appreciation of the pros and cons associated with prostate cancer screening.”

SOURCE: Journal of General Internal Medicine, August 2004.