Models attempt to pin down risk of radiation-induced breast cancer

A simulation study using two modeling approaches has shown that yearly digital breast cancer screening of U.S. women aged 40 to 74 may stave off 968 breast cancer deaths per 100,000 women screened—but the associated radiation exposure stands to cause 125 cancers leading to 16 deaths in the same cohort.

Diana L. Miglioretti, PhD, of the University of California-Davis and colleagues found that women with large breasts may be at greatest risk.

They further deduced that outcomes are affected by dose variability from screening, resultant diagnostic workup, initiation age and screening frequency.

Their study was published online Jan. 12 in the American College of Physicians’ Annals of Internal Medicine.

For women exposed to the highest amounts of mammography-related radiation (specifically, the 95th percentile), the researchers projected a bracing 246 cases of radiation-induced breast cancer leading to 32 deaths per 100,000 women.

They projected the 8 percent of women who have large breasts requiring extra views to suffer breast cancer at the rate of 266 cancer cases and 35 deaths per 100,000 women.

This compared with women with small or average-size breasts generating half as many cancer cases (113) and fewer than half as many deaths (15).

Miglioretti et al. also found biennial rather than annual screening (and starting at 50 years old) can reduce the risk for radiation-induced cancer fivefold.

Looking at false-positive results as a precipitator of greater radiation, the team found that additional imaging performed following these cases accounted for a quarter of the radiation dose received by women at the 95th percentile compared with only one tenth of the radiation dose received by women at the mean.

In their study discussion, the authors cite previous research showing that radiation dose is highly correlated with compressed breast thickness. This, they note, may increase over time with increasing population body mass index.

“Our study suggests that women with large breasts or breast augmentation receive greater radiation doses and may have a greater risk for radiation-induced breast cancer and breast cancer death,” they conclude. “Radiology practices should strive to ensure that large breasts are imaged with large detectors with the fewest number of views possible.”

The college is offering the full study free of charge online.