[Breast cancer screening program. Results of the process and impact indicators (1990-2002)]

Mammographic density and risk of breast cancer according to tumor characteristics and mode of detection: a Spanish population-based case-control study

INTRODUCTION

It is not clear whether high mammographic density (MD) is equally associated with all subtypes of breast cancer (BC). We investigated the association between MD and subsequent BC, considering invasiveness, means of detection, pathologic subtype, and the time elapsed since mammographic exploration and BC diagnosis.

METHODS

BC cases occurring in the population of women who attended screening from 1997 through 2004 in Navarre, a Spanish region with a fully consolidated screening program, were identified via record linkage with the Navarre Cancer Registry (n = 1,172). Information was extracted from the records of their first attendance at screening in that period. For each case, we randomly selected four controls, matched by screening round, year of birth, and place of residence. Cases were classified according to invasiveness (ductal carcinoma in situ (DCIS) versus invasive tumors), pathologic subtype (considering hormonal receptors and HER2), and type of diagnosis (screen-detected versus interval cases). MD was evaluated by a single, experienced radiologist by using a semiquantitative scale. Data on BC risk factors were obtained by the screening program in the corresponding round. The association between MD and tumor subtype was assessed by using conditional logistic regression.

RESULTS

MD was clearly associated with subsequent BC. The odds ratio (OR) for the highest MD category (MD >75%) compared with the reference category (MD <10%) was similar for DCIS (OR = 3.47; 95% CI = 1.46 to 8.27) and invasive tumors (OR = 2.95; 95% CI = 2.01 to 4.35). The excess risk was particularly high for interval cases (OR = 7.72; 95% CI = 4.02 to 14.81) in comparison with screened detected tumors (OR = 2.17; 95% CI = 1.40 to 3.36). Sensitivity analyses excluding interval cases diagnosed in the first year after MD assessment or immediately after an early recall to screening yielded similar results. No differences were seen regarding pathologic subtypes. The excess risk associated with MD persisted for at least 7 to 8 years after mammographic exploration.

CONCLUSIONS

Our results confirm that MD is an important risk factor for all types of breast cancer. High breast density strongly increases the risk of developing an interval tumor, and this excess risk is not completely explained by a possible masking effect.

[Assessment of results in the early diagnosis of breast cancer program in Asturias Community]

OBJECTIVE

To evaluate and disseminate the intermediate results of a breast cancer early detection program in the Asturias Community.

MATERIAL AND METHODS

We report the results of screening examinations performed between 2005 and 2009, using the indicators proposed in the European Guidelines on Quality Assurance in Mammography Screening. The information sources for breast cancer cases diagnosed were the pathology information system and the information on the characteristics of the tumour from the pathology report. The classification of the diagnostic features of the program was from its own information system.

RESULTS

A total of 1,384 breast cancers were diagnosed in the program target population during the study period, of which 49% were diagnosed in the program, 13% were interval cancers, 17% were diagnosed in women who chose not to participate in the program, and 22% in women who for various reasons had not been invited to participate. The most advanced diagnoses were made in the group of interval cancers and the earliest diagnoses were made in the uninvited population.

CONCLUSIONS

When the healthcare system is directed towards the asymptomatic population to provide a measure of prevention, it must ensure that there is a favourable balance. The results of this evaluation are consistent with accepted standards and with those found in other assessments.