Women have been told they should have screening for cervical cancer with a pap test every year. The visit to the gynecologist or internal medicine physician has been a right of passage for most young women and most are very compliant with that annual visit throughout their lives.
Well, the times they are a-changin’ because new guidelines issued by the US Preventative Services Task Force and the American Cancer Society say women should undergo screening NO MORE OFTEN than every 3 years starting at age 21. To further strengthen this recommendation, even the American Society for Clinical Pathology (those folks that read the pap smears) agrees with the recommendation. They also recommend stopping routine pap smears after age 65 for women who have had 3 negative Pap test results in the past 10 years. These women are just not at high risk.
So why the change? Read more »
*This blog post was originally published at EverythingHealth*
A new analysis in the American Journal of Preventive Medicine, “The Public’s Response to the U.S. Preventive Services Task Force’s 2009 Recommendations on Mammography Screening,” included a content analysis of news stories and social media posts around the time of the USPSTF announcement. The authors report:
“Of the 233 newspaper articles, blog posts, and tweets coded, 51.9% were unsupportive, and only 17.6% were supportive. Most newspaper articles and blog posts expressed negative sentiment (55.0% and 66.2%, respectively)….The most common reasons mentioned for being unsupportive of the new recommendations were the belief that delaying screening would lead to later detection of more advanced breast cancer and subsequently more breast cancer-related deaths (22.5%) and the belief that the recommendations reflected government rationing of health care (21.9%).
These results are consistent with previous studies that suggest a media bias in favor of mammography screening.”
Also see an accompanying editorial by Task Force members Diana Petitti and Ned Calonge.
*This blog post was originally published at Gary Schwitzer's HealthNewsReview Blog*
Emergency patients with acute abdominal pain feel more confident about medical diagnoses when a doctor has ordered a computed tomography (CT) scan, and nearly three-quarters of patients underestimate the radiation risk posed by this test, reports the Annals of Emergency Medicine.
“Patients with abdominal pain are four times more confident in an exam that includes imaging than in an exam that has no testing,” said the paper’s lead author. “Most of the patients in our study had little understanding of the amount of radiation delivered by one CT scan, never mind several over the course of a lifetime. Many of the patients did not recall earlier CT scans, even though they were listed in electronic medical records.”
Researchers surveyed 1,168 patients with non-traumatic abdominal pain. Confidence in medical evaluations with increasing levels of laboratory testing and imaging was rated on a 100-point scale. Then, to assess cancer risk knowledge, participants rated their agreement with these factual statements: “Approximately two to three abdominal CTs give the same radiation exposure as experienced by Hiroshima survivors,” and “Two to three abdominal CTs over a person’s lifetime can increase cancer risk.” Read more »
*This blog post was originally published at ACP Internist*
It’s easy to think of medical tests as black and white. If the test is positive, you have the disease; if it’s negative, you don’t. Even good clinicians sometimes fall into that trap. Based on the pre-test probability of the disease, a positive test result only increases the probability by a variable amount. An example: if the probability that a patient has a pulmonary embolus (based on symptoms and physical findings) is 10% and you do a D-dimer test, a positive result raises the probability of PE to 17% and a negative result lowers it to 0.2%.
Even something as simple as a throat culture for strep throat can be misleading. It’s possible to have a positive culture because you happen to be an asymptomatic strep carrier, while your current symptoms of fever and sore throat are actually due to a virus. Not to mention all the things that might have gone wrong in the lab: a mix-up of specimens, contamination, inaccurate recording…
Mammography is widely used to screen for breast cancer. Most patients and even some doctors think that if you have a positive mammogram you almost certainly have breast cancer. Not true. A positive result actually means the patient has about a 10% chance of cancer. 9 out of 10 positives are false positives.
But women don’t just get one mammogram. They get them every year or two. After 3 mammograms, 18% of women will have had a false positive. After ten exams, the rate rises to 49.1%. In a study of 2400 women who had an average of 4 mammograms over a 10 year period, the false positive tests led to 870 outpatient appointments, 539 diagnostic mammograms, 186 ultrasound examinations, 188 biopsies, and 1 hospitalization. There are also concerns about changes in behavior and psychological wellbeing following false positives.
Until recently, no one had looked at the cumulative incidence of false positives from other cancer screening tests. A new study in the Annals of Family Medicine has done just that.
They took advantage of the ongoing Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial to gather their data. In this large controlled trial (over 150,000 subjects), men randomized to screening were offered chest x-rays, flexible sigmoidoscopies, digital rectal examinations and PSA blood tests. Women were offered CA-125 blood tests for cancer antigen, transvaginal sonograms, chest x-rays, and flexible sigmoidoscopies. During the 3-year study period, a total of 14 screening tests were possible for each sex. The subjects didn’t all get every test.
By the 4th screening test, the risk of false positives was 37% for men and 26% for women. By the 14th screening test, 60% of men and 49% of women had had false positives. This led to invasive diagnostic procedures in 29% of men and 22% of women. 3% were minimally invasive (like endoscopy), 15.8% were moderately invasive (like biopsy) and 1.6% involved major surgical procedures (like hysterectomy). The rate of invasive procedures varied by screening test: 3% of screened women underwent a major surgical procedure for false-positive findings on a transvaginal sonogram.
These numbers do not include non-invasive diagnostic procedures, imaging studies, office visits. They do not address the psychological impact of false positives. And they do not address the cost of further testing.
These data should not be over-interpreted. They don’t represent the average patient undergoing typical cancer screening in the typical clinic. But they do serve as a wake-up call. Screening tests should be chosen to maximize benefit and minimize harm. Organizations like the U.S. Preventive Services Task Force try to do just that; they frequently re-evaluate any new evidence and offer new recommendations. Data like these on cumulative false positive risks will help them make better decisions than they could make based on previously available single-test false positive rates.
“In a post earlier this year, I discussed the pros and cons of PSA screening. Last year, I discussed screening ultrasound exams offered direct to the public to bypass medical judgment). If you do 20 lab tests on a normal person, statistically one will come back false positive just because of the way normal lab results are determined. Figuring out which tests to do on a given patient, either for screening or for diagnosis, is far from straightforward.
This new information doesn’t mean we should abandon cancer screening tests. It does mean we should use them judiciously and be careful not to mislead our patients into thinking they offer more certainty and less risk than they really do.
*This blog post was originally published at Science-Based Medicine*