5373. Screening-Detected and Interval Breast Cancers in Young Women
Authors * Denotes Presenting Author
  1. Manisha Bahl *; Harvard Medical School; Massachusetts General Hospital
There is limited published research about breast cancers in young women (<40 years of age). The purpose of this study is to determine the rates and characteristics of screening-detected and interval breast cancers in women aged 30 - 39 years.

Materials and Methods:
Screening mammograms obtained in women aged 30 - 39 from January 2007 to June 2019 at an academic medical center were retrospectively reviewed. All examinations performed from 2013 to 2019 included digital breast tomosynthesis. Characteristics of the screening-detected and interval breast cancers were collected. Standard performance metrics, including cancer detection rate (CDR) and abnormal interpretation rate (AIR), were calculated.

Over the study period, 4150 women aged 30-39 underwent 4448 screening mammograms. The overall CDR was 2.9 per 1000 examinations (13/4448), AIR was 9.3% (413/4448), PPV 1 was 3.1% (13/413), sensitivity was 81.3% (13/16), specificity was 91.0% (4032/4432), and false-negative rate (FNR) was 0.7 per 1000 examinations (3/4448). There were 13 screening-detected cancers, including six cases of invasive ductal carcinoma, and seven cases of ductal carcinoma in situ, all of which were diagnosed in women aged 35 - 39. Three false-negative cancers were detected based on symptoms (<em>n</em> = 2) and high-risk screening MRI (<em>n</em> = 1) in women aged 36-38. The two interval cancers detected based on symptoms were both invasive ductal carcinomas with metastases to the ipsilateral axillary lymph nodes. The one false-negative cancer detected on high-risk screening MRI was grade 2 ductal carcinoma in situ.

In a study cohort of more than 4000 women aged 30 - 39 who underwent screening mammography, the CDR was 2.9 per 1000 examinations, and the FNR was 0.7 per 1000 examinations. Of the screening-detected cancers, approximately half were invasive cancers and half were in situ cancers. This study sheds insight into the rates and characteristics of breast cancers in young women, which could inform future guidelines about the appropriateness and frequency of screening in this patient population.