SLATE: How Much Radiation Do You Get From a Mammogram? Not much.

How Much Radiation do you get from a Mammogram? Not Much.
By Brian Palmer, Slate, Posted Thursday, Nov. 19, 2009, at 6:11 PM ET

The U.S. Preventive Services Task Force recommended Monday that women without risk factors for breast cancer wait until their 50s before going in for regular mammograms. That's because early screening yields almost 50 times as many false positives as true cancers, triggering unnecessary biopsies and anxiety, and early detection doesn't do much good in 85 percent of cases anyway.

The Task Force noted that the radiation exposure associated with mammography was a minor factor in their recommendation; on Wednesday, Slate's Darshak Sanghavi wrote, "It's possible the radiation from those mammograms may end up causing more cancers than they prevent." How much radiation is in a mammogram?

An average of 70 millirems—roughly the dose you'd receive from your normal, everyday environment over a period of two and a half months. Most of our lifetime exposure to radiation comes from radon produced by decaying uranium in soil and rocks. Enough of this gas gets trapped in your house to deliver about 200 millirems per year.

Food, which incorporates uranium from the soil, adds to this total, as do air travel, smoking, and radioactive atoms inside your body. But that's no reason to worry: Studies have shown no increased risk of cancer among people experiencing as many as 1,000 millirems per year of background radiation. (As a general rule, though, you're better off with less exposure.)

The dosage figures for environmental radiation refer to effects on the whole body, but radiation delivered to specific body parts can be more or less destructive. Tissues that generate new cells more rapidly, like the thyroid or bone marrow, are particularly vulnerable.

Breast tissue is somewhat unusual, since the rate of cell turnover varies with the amount of estrogen. As a result, the breasts are much less susceptible to radiation among post-menopausal women. (That's one reason why it might be a good idea for women to wait a few more years before starting with the routine exams.)

Still, the dosage number cited above—70 millirems per mammogram—refers to a total "effective dose" that's been adjusted to account for the relative vulnerability of breast tissue averaged over a woman's lifespan. (Men are not included in the calculation.) In terms of these adjusted rates, the mammogram is pretty mild compared with other medical tests. A spine X-ray delivers twice as much radiation, a common kidney procedure quadruple. If you needed a CT scan of your abdomen, you'd get 14 times more. (Of course, you may not be getting these procedures every year.)

So what are the chances that a few mammograms in your 40s will cause breast cancer? No one is really sure, because it's difficult to construct a study that separates the mammograms that caused cancer from the mammograms that merely detected it. But the consensus is that mammography alone is very unlikely to cause breast cancer.

The only thing researchers can say with any confidence is that early and regular mammography increases the risk of disease for those women who have had prior exposure to high doses of radiation—either through cancer treatment, frequent chest X-rays to monitor tuberculosis, or employment in the atomic weapons industry.

Got a question about today's news? Ask the Explainer.

Explainer thanks Penny Butler and Shawn Farley of the American College of Radiology.

Miami Herald: Some health screenings may do more harm than good

Some health screenings may do more harm than good

Just excess radiation, one doctor says.

• Photo

Common diagnostic screenings
STRESS TEST
• For women older than 50 and men older than 40 embarking on a strenuous exercise program. Also for those with shortness of breath or chest pain.

BLOOD TESTS
High sensitivity-C-reactive protein -- indicates inflammation of the arteries.
Lp(a) -- for those with a strong family history of early cardiovascular disease.
ApoB -- to help evaluate risk of cardiovascular disease. Dr. Arthur Agatston recommends it when the total triglycerides are high and the HDL (good cholesterol) is low.
PSA -- the American Urological Association says it should be offered to men 40 or older who have a life expectancy of at least 10 years; others suggest a baseline screening at 50. Not for men over 75. Early findings in two screening studies had conflicting results: a European study found it cut the death rate by 20 percent; an American study found no benefit.

GENETIC TESTS
ApoE -- indicates genetic risk for Alzheimer's disease. For those who are concerned about or have a family history of the memory disorder.
Parkin and lark2 -- mutations in these genes indicate a risk for Parkinson's disease. Geneticist Jeffery Vance suggests that those with a strong family history, where multiple generations had Parkinson's, should ask their doctor about these genetic tests.

DIAGNOSTIC SCANS
Mammograms -- to detect breast cancer in women, baseline test at age 40, then annually. Not recommended for younger women because their breast tissue is too dense and breast cancer is relatively rare in that age group. After age 70, at discretion of the patient and her doctor.

BY KATHRYN W. FOSTER, Miami Herald, 03 Nov 2009

... Tests can tell if we have a high risk of prostate cancer, Alzheimer's, Parkinson's disease and various genetic disorders. CT scans can examine every inch of our bodies.

Are all these tests wise for a healthy adult? While mammograms and blood pressure readings have become part of annual checkups for most Americans, the explosion in preventative health exams has triggered a debate over which tests are necessary and which ones simply drive up the cost of health care -- or actually harm a patient.

Some doctors warn that certain screenings may do more harm than good because they expose the body to unnecessary radiation or raise questions that lead to further, invasive probing. Research suggests that some CT scans increase the risk of radiation-induced cancer.

"There are [genetic] tests that could be run on all of us,'' says Dr. Jeffery M. Vance, chairman of the University of Miami's Dr. John T. Macdonald Foundation Department of Medical Genetics. But "you need to understand why you're doing it. Make sure it's answering the question you want answered.''
CT scans are "being used for all sorts of diagnostic purposes not envisioned in the past, such as detecting heart disease, [conducting] virtual colonoscopies,'' says Dr. Jeffrey Neitlich, chairman of the Department of Radiology at Mount Sinai Medical Center.

"Patients shouldn't be scared away from CT scans if they need them, but shouldn't have them routinely.''

A study in the August New England Journal of Medicine suggests that as many as 4 million Americans a year are exposed to high doses of radiation from diagnostic scans, with a nuclear heart stress test called the myocardial perfusion scan being the single biggest contributor.

TOTAL-BODY SCANS
Particularly worrisome to Neitlich are full-body scans on healthy people. There has been ``no scientific publication demonstrating that a whole-body CT scan has any impact on life expectancy or quality of life. Therefore, at least at the current time, it's just excess radiation without any proven benefit,'' he says.

While cancer screenings are often life-saving, not all the information is helpful. Among the possible drawbacks, according to the U.S. Preventive Services Task Force:
• Results that falsely indicate cancer, leading to additional tests and worry.
• Failure to find an existing cancer so that the patient ignores symptoms while the disease continues unchecked.
• Detecting slow-growing or non-fatal cancers, leading to treatment that could have been avoided.

PROSTATE CANCER
The American Cancer Society no longer recommends routine PSA blood tests, saying doctors and patients should discuss the implications first.
"Some prostate cancers grow so slowly that they would likely never cause problems. Because of an elevated PSA level, some men may be diagnosed with a prostate cancer that . . . would never have caused any symptoms or lead to their death,'' the ACS writes in its online screening guide.

HEART TESTS
There's disagreement about which tests should be given. Dr. Michael Ozner, director of Wellness and Prevention for Baptist Health South Florida, recommends three blood tests that include the ApoB ("predictive of who's going to have a heart attack'') and the LP(a), which can help detect heart and vascular disease.

But South Beach Diet doctor Arthur Agatston, an associate professor at UM's medical school, recommends the ApoB only ``if the total tri-glycerides are high and the HDL [good cholesterol] is low.'' He also uses advanced blood tests, CT scans and even genetic tests.

Dr. Melissa Tracy, head of UM's cardiac rehab, would try other treatments before ordering the ApoB or the Lp(a).
"For the average person, we don't have evidence-based medicine that treating an elevated ApoB or Lp(a) leads to a positive outcome,'' she says.

Ozner's third recommendation is the high-sensitivity CRP blood test, to tell "whether arteries are inflamed,'' Studies have shown that people with elevated CRP levels and normal cholesterol were at increased risk of a heart attack, he says.

"In the past we've treated cardiovascular disease like a plumbing problem,'' Ozner says. "Now we know it's not a cholesterol storage disease, but a chronic inflammation disease. We have three tests that are very important to uncover hidden risks, yet people are bombarded with ads to get 64-slice CT scans.''

Ozner, whose book The Great American Heart Hoax: Lifesaving Advice Your Doctor Should Tell You About Heart Disease Prevention (But Probably Never Will) was published last year, calls the 64-slice heart CT scan for healthy people ``one of the biggest hoaxes perpetuated on the public.

"All that does is gives the patient an inordinate amount of radiation and sends people down the slippery slope to more and more medical intervention,'' he says. "If you're a man or woman in the ER with the proverbial elephant on your chest, I'm all for CT scans'' and other interventions.

A recent study found the median level of radiation in a heart CT scan is equal to 600 chest X-rays, although the levels varied widely.

"There are a lot of different ways to do cardiac CT scans. You can take two different centers and get twice the radiation at one as at the other,'' says Mount Sinai's Neitlich.

ALZHEIMER'S
As for Alzheimer's disease, many diagnostic tools are in the works. The ApoE gene test is already available.

Vance warns against genetic testing by mail, partly because some of the factors detected by these tests raise alarms when the risk really isn't that high.

"The results are misleading,'' Vance says. "It's important to have it done with a genetic counselor or a doctor to discuss what it means . . . Other than the very rare mutation, there is no test that's going to tell you 100 percent that you'll get Alzheimer's.''

----------------ooooooooooo000000000000oooooooooo-----------------------

Screening for Prostate and Breast Cancers

Have the benefits been overstated?

Screening for prostate and breast cancers has been promoted heavily in the U.S., and annual screening costs are US$20 billion for just these two cancers. 

Lifetime diagnoses of prostate cancer were made in 1 of 11 white men in 1980; in 2009, the risk is 1 in 6. 

For breast cancer, risks were 1 in 12 in 1980 and 1 in 8 in 2009. 

Authors of a highly publicized JAMA review now challenge the value of such intensive screening.

If screening accurately identifies cancer at an early treatable stage, the incidence of localized cancer should increase after screening is implemented, and the incidence of metastatic cancer should decline. Because this pattern has occurred for neither breast nor prostate cancer, screening simply might identify low-risk non–life-threatening cancers that then are treated inappropriately with aggressive therapy. 

By comparison, screening for colon and cervical cancers has led to significantly fewer cases of advanced disease. The observed decline in prostate cancer–related mortality in the last 20 years probably is not attributable to screening but, rather, to aggressive new adjuvant therapies.

The costs associated with screening are substantial. 

For breast cancer, avoiding 1 cancer-related death requires annual screening of more than 800 women (age range, 50–70) for 6 years, which generates hundreds of biopsies and overly aggressive treatment for many patients with low-grade cancers.

The authors recommend greater focus on identifying new biomarkers that differentiate low- and high-risk cancers, minimalist approaches that are appropriate for treating patients with low-risk cancers, better tools to guide physicians and patients in informed decision making, and a greater focus on prevention and screening in high-risk patients rather than broad indiscriminate screening.

— Thomas L. Schwenk, MD
Published in Journal Watch General Medicine October 29, 2009

Reference: Esserman L et al. Rethinking screening for breast cancer and prostate cancer. JAMA 2009 Oct 21; 302:1685.