The “should we shouldn’t we” debate continues in regards to routine breast cancer screening, with new research from Harvard School of Public Health (HSPH), indicating that between 15% and 25% of cases are overdiagnosed.

Routine mammograms have become the norm since the late 1980s, and have been thought to be the frontline in the fight against breast cancer. Women over 40 generally have a yearly screening. However, more recently physicians and patients alike have begun to question the necessity of blasting the breasts with X-Rays every year, not to mention putting women through the discomfort of the examination which is fairly aggressive on the breast themselves, and somewhat invasive to the patient psychologically. False positives can also lead to a great deal of stress on the patient, as well as unnecessary biopsies and further unneeded doctor’s appointments and tests.

With new cancer medicine on the market, the detractors of breast cancer screening are saying that the disease is more easily treated, and that many women are far more aware of checking their breasts regularly, making the routine mammograms a costly and unnecessary exercise in public health.

The Havard study was made from data of women in Norway, and lead author Mette Kalager, a visiting scientist at HSPH and a researcher at the Telemark Hospital in Norway clarifies her work :

“Mammography might not be appropriate for use in breast cancer screening because it cannot distinguish between progressive and non-progressive cancer … Radiologists have been trained to find even the smallest of tumors in a bid to detect as many cancers as possible to be able to cure breast cancer. However, the present study adds to the increasing body of evidence that this practice has caused a problem for women – diagnosis of breast cancer that wouldn’t cause symptoms or death.”

Kalager goes on to make the valid point that her findings should push women and their doctors to be well-informed and balanced in their approach. Now that the three-decade public health drive to educate and screen the population for breast cancer (which is relatively easily treated if caught early on), has matured, potential benefit from routine mammograms should be offset against its drawbacks. These can include mental distress, biopsies, surgeries, or chemotherapy and hormone treatments for disease that would never have caused symptoms.

Kalager and her team analyzed data from nearly 40,000 women with invasive breast cancer in Norway. Nearly 8,000 of them were diagnosed during the 10-year roll out of the Norwegian Breast Cancer Screening Program, which began in 1996, for women ages 50 through 69. The program in Norway was rolled in gradually, so researchers were able to compare those that were screened against those that were not. They also looked at data from before the 1996 roll out, going back to 1986, to look at diagnoses of breast cancer in women that had no routine screening.

Their idea, which makes good sense, was that if routine screening was as successful as its advocates claim, then the number of late stage diagnoses should have fallen, quite considerably. Unfortunately, this was not the case – what they did find was a great deal of over diagnosis:

  • 7,793 women diagnosed with breast cancer through participation in the screening program
  • 7,793 women diagnosed with breast cancer through participation in the screening program
  • For every 2,500 women invited to screening, 2,470 to 2,474 will never be diagnosed with breast cancer and 2,499 will never die from breast cancer
  • Only one death from breast cancer will be prevented
  • But 6 to 10 women out of 2500, will be overdiagnosed, and treated with surgery, radiation therapy, and possibly chemotherapy without any benefit.

The numbers are actually quite appalling, harming between six and ten patients to save just one, and are by no means within a reasonable margin of error. On the other hand, recent research from Holland has shown their national screening program to be quite successful in preventing breast cancer. It is therefore worth balancing both points of view and seeing that perhaps the truth lies somewhere in the middle of the two arguments. Give the patients the option for routine screening, present them with the benefits and drawbacks, educate them to examine themselves more often, and when positive results do come back from routine screening, know that they might not present the full picture.

Written by Rupert Shepherd