Facts/fallacies on breast and ovarian cancer screening

Breast cancer specialist Dr. Susan Love has an essay in the New York Times, “Real Race in Cancer Is Finding Its Cause,” in which she says the recent Komen/Planned Parenthood “furor misses an important fact: Women have been led to believe that screening is the best prevention.” She continues:

“…the original screening study done in the 1950s on postmenopausal women in New York demonstrated a 30-percent decrease in deaths from breast cancer. It also led to the conjecture that if we just carried out more screening at a younger age, and more often, we could improve these statistics and “win the war” on breast cancer.

But decades later, the success rate of screening remains nearly the same, even with much better imaging: routine mammography screening results in a 15- to 20-percent decrease in mortality in women over age 50.

Why hasn’t the situation improved? It turns out that there are at least five, and probably more, different types of breast tumors, growing and spreading at different rates. Some are so aggressive that they have almost always spread before they are visible on mammogram. But other tumors, if left alone, may never spread at all and do not need to be found.

This more complicated picture explains why mammography has not further decreased mortality. The X-rays find some cancers at a point that makes a lifesaving difference — but not all of them. British researchers estimated last year that one death from breast cancer is prevented for every 400 women ages 50 to 70 who are screened regularly over a 10-year period.”

ADDENDUM:  In the Cancer Letter, Paul Goldberg wrote:

The Susan G. Komen for the Cure Foundation and Planned Parenthood may have  had their differences over reproductive politics, but they march in lockstep when they overstate the promise of breast cancer screening to young women, a group of experts said to The Cancer Letter.

On the Wall Street Journal Health Blog, Katie Hobson reports that “Many Doctors Don’t Follow Ovarian-Cancer Screening Guidelines.” Excerpts:

“…the benefits of the available tests — a transvaginal ultrasound and a blood test that detects an antigen called CA-125 — haven’t been shown to outweigh their risks (such as complications from unnecessary surgery), or to reduce the number of deaths.

Despite that evidence, a new study finds that when presented with a scenario of a woman coming to her annual check-up, a significant percentage of physicians surveyed would screen for ovarian cancer.

Some 28.5% of the 1,088 primary-care docs  — OB/GYNs, family physicians and general internists — surveyed said they “sometimes” or “almost always” offered or ordered ovarian-cancer screening tests for low-risk women. When the vignette involved a woman at medium risk of the disease, that proportion jumped to 65.4% of physicians.

About a third of physicians reported believing that ultrasound or CA-125 blood testing is an effective screening test for ovarian cancer, the study found. It’s unclear why that is, and more research is needed to discover why, says Laura-Mae Baldwin, an author of the study and professor of family medicine at the University of Washington.

“We know that in medicine we have an enthusiasm for screening,” she says. “We want to find diseases before they can cause harm.”

The study also found that physicians were more likely to say they’d order screening for patients who requested it — even if the doctor herself didn’t believe screening was effective.

Journalism plays a role in spreading misinformation about screening.  For example, we recently highlighted a strong push for ovarian cancer screening by the editor of Prevention magazine – an editorial stance that was not supported by evidence.