What is the risk of induced cancer from undergoing a yearly mammogram, particularly for women under 40 years old who may be at high risk for breast cancer? 

The risk of radiation-induced breast cancer from annual mammography in women under 40, particularly those at high risk for breast cancer, is a significant consideration. For BRCA1 mutation carriers, the estimated lifetime risk of radiation-induced breast cancer mortality per 10,000 women from annual mammography is 26 (95% CI = 14 to 49) for screening at age 25-29 years, 20 (95% CI = 11 to 39) for screening at age 30-34 years, and 13 (95% CI = 7 to 23) for screening at age 35-39 years.[1]

A study by Evans et al. found no strong evidence for an increased risk of breast cancer 8-26 years after multiple mammograms in women in their 30s at moderate and high familial risk, with a relative risk of 1.12 (95% CI: 0.83 to 1.51).[2]

Additionally, the American College of Radiology (ACR) notes that while BRCA mutation carriers may be particularly susceptible to radiation, the low radiation dose from screening mammography does not demonstrably increase their breast cancer risk.[3]

In summary, the risk of induced cancer from yearly mammograms in women under 40, especially those at high risk, is present but relatively low. The decision to start screening should balance the potential benefits of early cancer detection against the risks of radiation exposure.

References

1. Estimated Risk of Radiation-Induced Breast Cancer From Mammographic Screening for Young BRCA Mutation Carriers.

Berrington de Gonzalez A, Berg CD, Visvanathan K, Robson M. Journal of the National Cancer Institute. 2009;101(3):205-9. doi:10.1093/jnci/djn440.

2. No Strong Evidence for Increased Risk of Breast Cancer 8-26 Years After Multiple Mammograms in Their 30s in Females at Moderate and High Familial Risk.

Evans DG, Kotre CJ, Harkness E, et al. The British Journal of Radiology. 2016;89(1059):20150960. doi:10.1259/bjr.20150960.

3. Breast Cancer Screening in Women At Higher-Than-Average Risk: Recommendations From the ACR.

Monticciolo DL, Newell MS, Moy L, et al. Journal of the American College of Radiology : JACR. 2018;15(3 Pt A):408-414. doi:10.1016/j.jacr.2017.11.034.

What is the risk of radiation-induced cancer from yearly mammograms in the normal population after the age of 40?

The risk of radiation-induced cancer from yearly mammograms in the normal population after the age of 40 is relatively low compared to the benefits of early cancer detection. According to a modeling study published in the Annals of Internal Medicine, annual screening of 100,000 women aged 40 to 74 years is projected to induce 125 breast cancer cases (95% CI, 88 to 178) and 16 deaths (95% CI, 11 to 23) due to radiation-induced breast cancer. [1]

Another study in Radiology estimated that for a cohort of 100,000 women screened annually from age 40 to 55 years and biennially thereafter to age 74 years, there would be 86 cancers induced and 11 deaths due to radiation-induced breast cancer. [2]

The American College of Physicians (ACP) also notes that annual screening from ages 40 to 74 years is associated with a lifetime attributable risk for radiation-induced breast cancer of 125 cases per 100,000 women.[3]

In summary, while there is a measurable risk of radiation-induced cancer from yearly mammograms, the risk is small and is generally outweighed by the benefits of early detection and reduced breast cancer mortality.

References

1. Radiation-Induced Breast Cancer Incidence and Mortality From Digital Mammography Screening: A Modeling Study.

Miglioretti DL, Lange J, van den Broek JJ, et al. Annals of Internal Medicine. 2016;164(4):205-14. doi:10.7326/M15-1241.

2. Risk of Radiation-Induced Breast Cancer From Mammographic Screening.

Yaffe MJ, Mainprize JG. Radiology. 2011;258(1):98-105. doi:10.1148/radiol.10100655.

3. Screening for Breast Cancer in Average-Risk Women: A Guidance Statement From the American College of Physicians.

Qaseem A, Lin JS, Mustafa RA, et al. Annals of Internal Medicine. 2019;170(8):547-560. doi:10.7326/M18-2147.