Biennial mammography necessary for women

Mammography screening, the test to detect breast diseases, every two years is necessary for women between 50-74 years of age, confirms a comprehensive analysis of six independent research studies.

For average risk populations, starting screening earlier or screening more often prevented a small number of additional deaths from breast cancer and potential screening harms, including over-diagnosis, false-positives, and benign biopsies, the findings showed.

With the new updated data, the Cancer Intervention and Surveillance Modelling Network (CISNET) results demonstrated the same finding as in 2009 -- that screening average-risk women biennially from ages 50 to 74 provides a reasonable balance of avoiding deaths. "We added digital mammography outcomes and the most modern treatments including therapy based on tumour molecular subtypes.

We also included additional results for risk levels, breast density, and women's other illnesses to help guide clinical practice considerations," said lead author, Jeanne S. Mandelblatt, of Georgetown Lombardi Comprehensive Cancer Center in Washington, US. "The bottom line is that mammography saves lives.

When to start screening and how often to undergo mammography, is a personal decision," Mandelblatt added. The evidence can be considered for public health recommendations for average risk women, the researchers suggested while adding, “none of us is the 'average' woman."

The researchers examined screening strategies with different starting ages (40, 45 or 50), and one- or two-year intervals between screening exams. In general, biennial strategies maintain an average of 81.2 percent of annual screening benefits, the findings, published in the Annals of Internal Medicine, showed.

Compared with biennial screening from ages 50-74, starting biennial screening at age 40 averts one more death per 1000 from breast cancer.
Annual screening from ages 50-74 averted 2 more deaths per 1000 compared to biennial screening.

For healthy older women with an average remaining life expectancy of 17 years, screening would be reasonable through age 78 or 80 and would have a minimal increase in over-diagnosis compared with stopping at age 74, the study showed.