The impact of screening mammography in women age 40-49 as a function of tumor biology.

Abstract

113 Background: Mammographic screening for women 40-49 years of age remains controversial based on results from earlier large scale, controlled mammography trials. Methods: From 2002-2006, 871 women aged 40-49 were diagnosed with breast cancer at Intermountain. The charts of all patients without a record of a screening mammogram at Intermountain (n= 436) were reviewed to confirm that they had not had a screening mammogram in the prior two years at any facility (Interval Cancers) and their survival was compared to 435 women who had their cancer diagnosed on a screening exam (Screen Detected). All patients were followed for at least 5 years via the tumor registry. Results: Stage distribution for Screen Detected/Interval cancers was 25.3/6.4% stage 0, 36.8/24.8% stage I, 24.6/35.6% stage II, 6.9/20.4% stage III and 0.5/3.4% stage IV. Overall, 67 patients (7.7%) did not have complete staging data. Overall survival was significantly better (p<.0001) for 40-49 year old women with Screen Detected compared to those with Interval cancers. 702 (79.6%) had ER/PR status recorded (83.5% ER/PR positive). Women with DCIS or LCIS did not have tissue sent for markers. 679 patients (76.9%) had HER2 status recorded (78.8% HER2 neg). Of the patients with both HER2 and ER/PR status recorded 10.4% were “triple negative.” Survival following screening mammography was significantly enhanced for women who were ER/PR positive (p<0.0001), HER2 negative (p=0.0065), or HER2 positive (p=0.0013). Survival was not improved by screening mammography for women who were ER/PR negative (p=0.3818) or for women who were triple negative (p=0.416). Conclusions: A minority of women age 40-49 who develop breast cancer (13%) have biologic features suggestive of aggressive disease and, after 5 years of follow up, they are not benefitted by screening mammography. The remaining 87% are clearly benefitted by screening mammography. Our results suggest that the discrepancies noted in the screening mammography trials in 40-49 year old women may have resulted from population variations in the proportion of women with unfavorable biology. Based in part on these results, we continue to recommend regular screening in the 40-49 year old cohort.