Immunology

Crude incidence rates of breast cancer among U.S. female active component service members have fluctuated slightly over the past 12 years, but have remained relatively stable, according to a new study.

As in the general U.S. population, with the exception of skin cancer, breast cancer is the most frequent cancer diagnosis among women. During the 13-year surveillance period from 2000 to 2012, 1,092 female active component members were diagnosed with breast cancer, according to the study published in the Medical Surveillance Monthly Report, a peer-reviewed journal on illnesses and diseases affecting service members from the Armed Forces Health Surveillance Center (AFHSC). Of those diagnoses, 244 (22.3 percent) of were ductal cinoma in situ (DCIS) cases. The overall crude incidence rate of breast cancer was 40.6 per 100,000 person-years (p-yrs); the lowest annual incidence rate was 28.6 per 100,000 p-yrs in 2006, and the highest annual incidence rate was 53.6 per 100,000 p-yrs in 2001.

"The most important observations from this study of active component service women were annual incidence rates of breast cancer have fluctuated up and down from year to year during the last 13 years but there has been no discernible long-term trend upward or downward," said Army Colonel William Corr, the deputy director of AFHSC's division of Epidemiology and Analysis. "In addition, approximately 22% of all breast cancers diagnosed during the period were ductal carcinoma in situ (DCIS), the least invasive form of breast cancer."

This report provides new estimates of breast cancer rates and expands upon previous analysis by providing incidence rates for DCIS. The surveillance period was January 1, 2000 to December 31, 2012. The surveillance population included all women who served in the active component of the U.S. Armed Forces at any time during the surveillance period. All data used to determine incident cancer cases were derived from records routinely maintained in the Defense Medical Surveillance System (DMSS) maintained by AFHSC.

Over the surveillance period, the crude incidence rate of DCIS cases was 9.1 per 100,000 p-yrs; for other (invasive) breast cancer diagnoses the rate was 31.5 per 100,000 p-yrs. While crude incidence rates of invasive breast cancer fluctuated during the period, the crude incidence rate in the final year of the surveillance period was slightly lower than the rate in the first year of the surveillance period (2012: 32.1 cases per 100,000 p-yrs; 2000: 33.8 cases per 100,000 p-yrs).

In contrast, crude incidence rates of DCIS fluctuated less dramatically during the period, but incidence rates were higher in 2012 than in the first year of the surveillance period (2012: 11.0 cases per 100,000 p-yrs; 2000: 8.0 cases per 100,000 p-yrs). While DCIS is less common than invasive breast cancer, the widespread adoption of breast cancer screening (i.e., mammography) has led to marked increases in DCIS diagnoses as most cases of DCIS are diagnosed through mammography screening.5

The strongest demographic correlate of increased risk of a breast cancer diagnosis was older age. For example, the highest rates of diagnoses were among those older than 40 years. Incident cases of DCIS were relatively uncommon in female military members under 40 years of age; crude incidence rates were sharply higher in those 40 years of age or older compared to those 35-39 years of age (79.0 per 100, 000 p-yrs and 16.5 per 100,000 p-yrs, respectively).