If you get all the recommended cancer screenings, how safe are you? Dr. Billy U. Philips Jr. and colleagues at Texas Tech University performed a unique study to find out. The purpose of cancer screening tests is to find the malignancy early, while it can be treated successfully. A major distinction between early and late stage cancer is the presence of metastases. Philips used data from the Texas Cancer Registry to check the ratio of metastatic to non-metastatic cancer diagnoses in Texas on a county by county basis. His team of researchers also analyzed data from the U.S. Census Bureau to quantify the degree of socioeconomic wealth or deprivation for each county. Statistical correlation then provided a measure of the success of improved health care for cancer.
For female genital system cancers, lung cancers, and all-type cancers taken as a whole, the ratio of metastatic to non-metastatic diagnoses were statistically correlated with socioeconomic deprivation. Philips and coauthors attributed these results to several factors, including better access to Pap smears in wealthier counties.
Surprisingly, the ratios of metastatic to non-metastatic cancer diagnoses were not correlated with socioeconomic status for breast cancer, prostate cancer, and colorectal cancers. Philips suggested these results tell us something about the success of screening tests. For colorectal cancer, the most common screening test (colonoscopy) is so effective that most patients never receive a diagnosis of cancer at all. Precancerous polyps are generally removed in the same procedure used for screening.
For breast cancer, the screening tests of mammography, clinical breast exam, and breast self-exam are not effective enough to produce a statistical correlation in the Texas county data, Philips reported. A report from the American Cancer Society echoes this evaluation. “Women also should be told about the limitations of mammography, specifically that mammography will not detect all breast cancers, and that some breast cancers detected with mammography may still have poor prognosis,” according to Dr. Robert A. Smith and colleagues.
The American Cancer Society report assures us that current screening guidelines save lives, but they are not sufficient to catch every cancer early enough. Research is in progress to develop improved screening techniques. In the meantime, cancer prevention efforts remain vitally important. It's not enough to rely on screening if you smoke, eat junk food, and remain obese. The steps we can take for ourselves are at least as important as anything our doctors can do for us.
References:
1. Philips BU et al, “Correlation of the ratio of metastatic to non-metastatic cancer cases with the degree of socioeconomic deprivation among Texas counties”, International Journal of Health Geographics 2011; 10:12. http://www.ncbi.nlm.nih.gov/pubmed/21294886
2. Smith RA et al, “Cancer screening in the United States, 2011”, CA: A Cancer Journal for Clinicians 2011; 61: 8 – 30. http://www.ncbi.nlm.nih.gov/pubmed/21205832
Reviewed June 8, 2011
Edited by Alison Stanton
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.