Study: Regular Mammography Screening Leads to Big Cut in Deaths

Regular mammography screening may reduce breast cancer deaths by 63 percent and a policy of inviting women to an organized mammography screening may reduce breast cancer deaths by 50 percent, according to researchers in Sweden.

The evaluation of organized screening outside of a research setting ("service screenings") was evaluated in a clinical setting, demonstrating the benefit obtained from service screening in two Swedish counties.

Researchers conducted a study of 6,807 women, ages 20 to 69, who had been diagnosed with breast cancer over a 29-year period. There were 1,863 deaths from the disease within the group, according to the study published in the journal Cancer.

The women were classified on whether they had been invited to undergo mammography and whether they had actually done so. Mortality was compared across three periods: 1968 to 1977, when no screening was available; 1978 to 1987, during which a randomized controlled trial of screening of women ages 40 to 74 took place; and 1988 to 1996, when all women, ages 40 to 69, were invited to undergo screening.

The mortality from breast cancer diagnosed in women ages 40 to 69 who were screened during the period of 1988 to 1996 fell by 63 percent compared with breast cancer mortality during 1968 to 1977 when no screening was available.

The mortality rate was 50 percent when breast cancer mortality among all of those who were invited to undergo mammography (non-attendees included) was compared to breast cancer deaths during the time when no screening was available. The reduction in mortality observed during the service screening period, adjusted for selection bias, was 48 percent, according to the researchers.

No significant change in breast cancer mortality was seen over the three time periods in women who did not undergo screening. This group included women ages 20 to 39 because these women were never invited to undergo screening, and women age 40 to 69 who did not undergo screening (not invited during the randomized trial, or invited during the second and third time periods but who declined).

Researchers concluded that although the evaluation of organized screening outside the research setting faces unique methodologic and conceptual challenges, definite benefit is obtained from service screenings.

Other Sources: Cancer