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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 15  |  Issue : 2  |  Page : 138-141

Sonographic breast density pattern among Nigerian women in Zaria


1 Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria
2 Department of Radiotherapy, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria
3 Nigeria Field Epidemiology and Laboratory Training Program, Abuja, Nigeria

Date of Web Publication14-Sep-2018

Correspondence Address:
Dr. S A Olarinoye-Akorede
Department of Radiology, Ahmadu Bello University Teaching Hospital, Zaria
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njbcs.njbcs_38_17

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  Abstract 


Background: Increased breast density is a known risk factor for breast cancer; as such, it is a pertinent consideration for any breast cancer awareness and screening exercise. Ultrasound is the most frequently requested breast imaging examination and is the preferred imaging modality for assessing dense breasts. Objectives: This paper aims at describing the sonographic breast density patterns among women in Zaria using the American College of Radiology breast imaging and reporting data system (BIRADS) lexicon to estimate the prevalence of different breast sonographic patterns in Zaria and to relate this with age, parity, and menopausal status of the women studied. Materials and Methods: This was a cross-sectional descriptive study of the sociodemographic and sonographic data of 503 women who presented for breast ultrasound at the Radiology department of Ahmadu Bello University Teaching hospital, Zaria, Nigeria between July 2014 and December 2016. Breast scans were performed using a Mindray DC-8 Ultrasound machine, equipped with a 7–12 mHz transducer. Data were analyzed using statistical package for social sciences software for windows version 20 (SPSS, Inc. Chicago Illinois, USA). Results: Five hundred and three women participated in the study. There were 415 premenopausal and 88 postmenopausal women whose mean age was 36.1 ± 12.8 years. The most common breast density pattern was heterogenous (49.1%), which was independent of family history of breast cancer. The least common breast density pattern was homogenous fibroglandular. Breast density decreased significantly with increasing age, parity, and menopausal status (P < 0.001). Conclusion: Heterogenous pattern (ACR type 3) was the predominant breast density pattern in this study. Because this breast pattern has been significantly associated with breast cancer, further studies are needed to estimate cancer risk among our women.

Keywords: Breast cancer, breast density, ultrasound, Zaria


How to cite this article:
Olarinoye-Akorede S A, Adamu A, Balogun M S. Sonographic breast density pattern among Nigerian women in Zaria. Niger J Basic Clin Sci 2018;15:138-41

How to cite this URL:
Olarinoye-Akorede S A, Adamu A, Balogun M S. Sonographic breast density pattern among Nigerian women in Zaria. Niger J Basic Clin Sci [serial online] 2018 [cited 2018 Dec 11];15:138-41. Available from: http://www.njbcs.net/text.asp?2018/15/2/138/241157




  Introduction Top


Ultrasound in breast imaging have gone beyond its historic role in the diagnosis of cysts due to the introduction of high-frequency transducers. It has shown high yield in distinguishing benign and solid masses and is a valuable tool where imaging is limited by breast density.[1],[2]

Sonographic appearance of the breast, like in mammography, varies for each woman because of the different proportions of epithelial and stromal tissue versus the fatty element present. Breasts with greater proportion of fibroglandular tissue are depicted sonographically as relatively more echogenic (dense) whereas fatty breasts appear relatively isoechoic (less dense). According to the Breast Imaging Reporting and Data System lexicon of the American College of Radiology (ACR-BIRADS) guidelines (2003),[3] three sonographic patterns are described in order of increasing density. Type 1: homogenously fatty (predominantly fatty) which is the least dense. Type 2: homogenous fibroglandular (mixed fatty and glandular), and type 3: heterogeneous (highly dense). When all the common risk factors associated with breast cancer such as age, sex, family history, lifestyle, and hormone use are considered, breast density pattern is associated with the most risk for developing cancer by 4–6 folds.[3],[4],[5],[6]

Dense breasts result in decreased sensitivity of mammography for cancer detection.[5] High-resolution ultrasound has better fibrous-glandular tissue differentiation and is the modality of choice for the assessment of young women (below the age of 40 years) who have dense breasts, as it overcomes the limitations of mammography.

This study aimed to describe the distribution of the different sonographic breast patterns among women in Zaria using the ACR-BIRADS lexicon to serve as a baseline for future studies in this locality.


  Materials and Methods Top


Ethical approval was obtained for this study conducted between July 2014 and December 2016. It involved 503 women who presented consecutively and underwent sonographic breast evaluation at the Radiology department of Ahmadu Bello University Teaching Hospital. They consisted of 415 premenopausal and 88 postmenopausal women. Young girls who were yet to attain menarche and male patients were excluded from this study. Breast scans were done using a Mindray DC-8 ultrasound machine with a linear array transducer of 7–12 MHz frequency. The patients' personal information and clinical history were extracted from the breast information sheet, which was completed by all patients prior to examination.

The performing radiologist carried out a physical examination of the breast and axilla first in the sitting position, then in the supine position with ipsilateral arm beneath the head noting relevant findings before commencing the scan. Subsequently, overlapping transverse and longitudinal scans as well radial and antiradial scanning was done in the real-time until the entire breast(s) were scanned. The nipple-areolar complex and lastly the axillae were also examined to include axillary tail breasts and assess nodal pathology.

The sonographic density pattern for each patient was interpreted by two radiologists. These findings were then documented based on the ACR-BIRADS [3] as follows: BIRADS 1 (fatty); BIRADS 2 (homogenous fibroglandular), and BIRADS 3 (heterogenous). Data was recorded and analyzed with statistical package for social sciences software for windows version 20 (SPSS, Inc. Chicago Illinois, USA).

Frequencies and proportions were depicted using tables and charts. Chi-square test was applied to assess the statistical relationship between the sonographic breast pattern and patient's sociodemographic variables such as age, parity, menopausal status, and family history of breast cancer.


  Results Top


A total of five hundred and three women were recruited into the study. The age range of the women was 13–90 years with a mean age of 36.1 ± 12.7 years. Women less than 30 years constituted the highest population 173 (34.4%) [Table 1]. Over two-thirds of the women [415 (82.5%)] were premenopausal while 88 (17.5%) were postmenopausal.
Table 1: Distribution of the women by Age, Parity and Menopausal status

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The heterogenous pattern (type 3) accounted for approximately half of the breast parenchymal patterns documented (49.1%), followed by homogeneous fatty pattern (type 1), which made up 28.4% of the total study sample. The least observed pattern was homogenous fibroglandular pattern (type 2) which made up less than one-third (22.5%) [Figure 1].
Figure 1: The frequency distribution of different breast density patterns

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[Figure 2] shows the proportions of the different parenchymal patterns with menopausal status of the women studied. The homogenous fatty pattern constituted 21.4% among the premenopausal women and 61% in the postmenopausal group; whereas the heterogenous pattern (type 3) made up 55% in the premenopausal group and 19% in the postmenopausal women. An inverse relationship was seen to exist between breast density and menopausal status. This inverse relationship was also observed with regards to increasing parity and age [Figure 3].
Figure 2: Breast density pattern versus menopausal status

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Figure 3: Breast density pattern versus parity

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  Discussion Top


Breast density pattern has been studied extensively with X-ray mammography with fewer ultrasound reports being available. This study examined the ultrasonographic breast parenchymal pattern among women in Zaria to bridge this gap. Our results showed that the most prevalent breast pattern was the heterogenous (type 3) which represents the dense breast category. Increased breast density is an important risk factor for cancer, independently or in association with other factors.[2],[4],[6],[7],[8],[9],[10],[11]

We also compared our findings with those obtained from the Southern part of Nigeria. This is because breast density pattern varies according to ethnicity and geographic location, irrespective of known lifestyle determinants of breast density such as age and parity.[12],[13],[14] In Ibadan, the predominant pattern was heterogenous (53%), which is similar to our study.[15] However, the least recognized breast pattern in the previous study was homogenous fatty (14%), whereas in our study it was homogenous fibroglandular. The lower mean age of our study population and a lower modal age group could account for these differences.

Our study findings show an inverse relationship between breast density versus age, parity, and menopausal status, which is consistent with previous reports.[6],[14],[15],[16] This finding is explained by atrophy of the glandular tissue of the breast and subsequent fatty replacement, which occurs in older, multiparous, and postmenopausal women.

Among 82 (16.3%) patients who either had a personal or family history of breast cancer, the predominant breast pattern was heterogenous.

The ACR classifies breast density into four X-ray mammographic categories, however in ultrasonography, three categories are defined.[3] Nonetheless, reports by Chou et al.,[16] Kaizer et al.,[17] and Blend et al.[18] have shown that breast parenchymal patterns on ultrasound correlated strongly with those on X-ray mammography. The main limitation of mammographic screening continues to be breast density which lowers its sensitivity,[19],[20],[21] thus giving ultrasound a central role in patients with dense breasts.

A study by Kelliowesky [21] in Northern California reported that approximately 47% of women undergoing screening mammography had mammographically dense breasts. In America, breast density is a national issue and several states have enacted a law that requires that women should be notified of their breast density status.[22],[23],[24],[25] Women with dense breasts are recommended to have supplemental ultrasound screening in addition to mammography.[26],[27],[28]

Overall, approximately half of our patients (49.1%) had dense breasts, i.e., ACR type 3. Ultrasound, which is cheaper than mammography, would be more affordable in our resource-constrained setting. Moreover, ultrasound is more available.

The performance of ultrasound in recent studies also revealed that its utility could surpass being just an adjunctive role to mammography in breast cancer detection. Comparable or even higher breast cancer detection rates have been achieved with ultrasound than mammography.[19],[27],[29]

Some authors advocate ultrasound alone as a primary screening tool.[29],[30] However, ultrasound is operator-dependent leading to inter or intraobserver variability. Furthermore, its low specificity causes increased biopsy rates.[29],[30] In addition, there is no randomized control trial yet to ascertain the impact of ultrasound screening alone on breast cancer mortality rates.[15]


  Conclusion Top


The dense breast parenchyma (type 3) was the predominant pattern among our women. Therefore, physicians need to sensitize patients about their breast density pattern. They need to know that dense breasts can mask breast masses on mammographic examinations and that ultrasound is an invaluable alternative.

Acknowledgements

We are grateful to Dr Mohammed H and Dr Bello N of the breast unit of the department of Radiology, Ahmadu Bello University Teaching Hospital for participating in the preliminary interpretation of the sonograms.

Financial support and sponsorship

Nil.

Conflicts of Interest

There are no conflicts of interest.



 
  References Top

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