BCDDP TRIAL: Between 1973 and 1981, a large screening project called The Breast Cancer Detection Demonstration Project (BCDDP) was begun in the U.S. The project involved 283,222 women in 29 centers. Women in the project received physical exams and five annual mammograms (only 51 percent of the women completed all five mammograms).

The project was not intended as a research study and did not include a control group of women who did not receive mammography for comparison.

Furthermore, in the midst of the project, controversy arose over the harmful effects of the X-ray exposure from the mammograms. Mammograms used in both HIP and BCDDP are considered primitive by today's standards and the dose of radiation to the breast was about 20 times more than that used today.

At the height of the BCDDP study, in 1976-7, several doctors including Dr. John Bailar III, editor of the Journal of the National Cancer Institute at that time, and now Professor of Biostatistics and Epidemiology at McGill University School of Medicine, raised the possibility that the radiation from mammograms was causing as many cancer deaths as it was preventing. As a result of these concerns, women under age 50 were dropped from the mammogram part of the project, unless they were in a high risk group. However, women in this age group did return every year for a physical exam.

However, the BCDDP did demonstrate the ability of mammography to pick up small cancers. Fifty nine percent of very early cancers were detected by mammography alone compared with six percent with physical exam alone.

THE SWEDISH TWO COUNTY STUDY: This randomized study was begun in 1977 and ended in 1984, and involved 77,000 screened women and 56,000 women in the control group. Mammograms (a single view of each breast) were done every two years for women aged 40 to 49; and every three years for women over 50.

As of December 31, 1990 the study showed an overall reduction in breast cancer death rate of 30 percent, especially in the over 50 group.

But for women aged 40 to 49, more breast cancer deaths occurred in the screened group and 50 percent of breast cancers were detected in the intervals between screenings. One third of breast cancer deaths occurred in women who did not attend screening, especially those over age 70 years.

Three other studies, although not randomized, showed between 30 to 50 percent reduction in annual breast cancer death rate in screened women over the age of 50. Two of the studies took place in Holland and one in Italy.

What Does A 30 Percent Reduction In Breast Cancer Death Rate Really Mean ?

Dr. Peter Skrabenek is an outspoken critic of screening mammography and lectures on community medicine in Dublin. He says that to put this figure into its proper perspective, a 30 percent death rate reduction does not mean that one in three women with breast cancer is saved, it means that for each 15,000 women screened, there will be one less death from breast cancer each year.

Another way of looking at this, according to Dr. Baines, is that for every ten women who would die of breast cancer without breast screening, seven will still die even with breast screening.

Unfavourable Studies

Malmo, Sweden was the site of another large study, involving 21,000 women in the study group who had mammograms every 18 to 24 months, and 21,000 women in the control group. This study showed that "deaths from breast cancer were reduced by 20 percent in women over 55 or older despite a lower participation in this group."

However, women younger than 55 in the study group showed a 29 percent higher death rate from breast cancer. "Although this could be a random phenomenon," the researchers say, "negative results of a screening mammogram may have falsely reassured some patients and led to a deleterious delay in diagnosis."

The Malmo study has been criticized for its design, and also for the fact that women in the control group had mammograms that led to the detection of 20 percent of cancer in that group.