Stereotactic breast biopsies: Radiological-pathological concordance in a South African referral unit

Background: Stereotactic breast biopsies have become the gold standard for tissue diagnosis in non-palpable, sonographically occult breast abnormalities seen on mammogram. Only limited data exist in South Africa on the correlation between imaging findings and stereotactic biopsy histology.Objectives: To describe the mammographic findings and histological diagnosis in patients who underwent stereotactic breast biopsy at a referral hospital. In addition, to evaluate the proportion of malignancy in each Breast Imaging Reporting and Data System (BI-RADS) category.Method: A retrospective review of stereotactic breast biopsies was performed. Imaging characteristics (including BI-RADS category) and histological diagnosis were recorded. Using histopathology, cases were classified as benign, high-risk or malignant.Results: A total of 131 biopsies, from 123 patients, were included in the study. Most biopsies were performed on asymptomatic patients (79.3%, 104/131). The majority were categorised as BI-RADS 4 and demonstrated calcifications. Histology revealed a malignant diagnosis in 40 (30.5%) patients, a high-risk lesion in 8 (6.1%) patients and a benign diagnosis in 83 (63.4%) patients. There was a stepwise increase in the proportion of malignancy from BI-RADS category 3 to 5. When compared with surgical histology, the stereotactic biopsies demonstrated an overall ductal carcinoma in situ (DCIS) underestimation rate of 10.3%.Conclusion: Despite resource restrictions, stereotactic breast biopsies performed in a South African context produce radiological-pathological concordance in keeping with BI-RADS guidelines, as well as with local and international studies.

Patterns of aggressiveness: risk of progression to invasive breast cancer by mammographic features of calcifications in screen-detected ductal carcinoma in situ

BACKGROUND

Mammographic features of calcifications on mammograms showing invasive breast cancer are associated with survival. Less is known about mammographic features and progression to invasive breast cancer among women treated for ductal carcinoma in situ (DCIS).

PURPOSE

To investigate mammographic features of calcifications in screen-detected DCIS in women who later did and did not get diagnosed with invasive breast cancer.

MATERIAL AND METHODS

This registry-based nested case-control study analyzed data from women with screen-detected DCIS in BreastScreen Norway, 1995-2016. Within this cohort of women with DCIS, those who were later diagnosed with invasive breast cancer (cases) were matched (1:2) to women who were not diagnosed with invasive breast cancer (controls) after their DCIS and by the end of 2016. Information on mammographic features were collected by a national radiological review, where screening mammograms were reviewed locally at each of the 16 breast centers in Norway. We used conditional logistic regression analysis to estimate associations between mammographic features of calcifications in the DCIS mammogram and the risk of subsequent invasive breast cancer.

RESULTS

We found a higher risk of invasive breast cancer associated with fine linear branching (casting) morphology (odds ratio 20.0; 95% confidence interval [CI] 2.5-158.9) compared to fine linear or fine pleomorphic morphology. Regional or diffuse distribution showed an odds ratio of 2.8 (95% CI 1.0-8.2) compared to segmental or linear distribution.

CONCLUSION

Mammographic features of calcifications in screen-detected DCIS were of influence on the risk of invasive breast cancer. Unfavorable characteristics of DCIS were fine linear branching morphology, and regional or diffuse distribution.

Low-risk DCIS. What is it? Observe or excise?

The issue of overdiagnosis and overtreatment of lesions detected by breast screening mammography has been debated in both international media and the scientific literature. A proportion of cancers detected by breast screening would never have presented symptomatically or caused harm during the patient's lifetime. The most likely (but not the only) entity which may represent those overdiagnosed and overtreated is low-grade ductal carcinoma in situ (DCIS). In this article, we address what is understood regarding the natural history of DCIS and the diagnosis and prognosis of low-grade DCIS. However, low cytonuclear grade disease may not be the totality of DCIS that can be considered of low clinical risk and we outline the issues regarding active surveillance vs excision of low-risk DCIS and the clinical trials exploring this approach.

Association between radiologists' and facilities' characteristics and mammography screening detection of ductal carcinoma in situ

PURPOSE

The aim of our study was, first, to measure association between radiologists and facilities characteristics and DCIS detection. Second, to assess whether those characteristics affect differently the likelihood of detection of DCIS versus invasive breast cancer. When applicable, we examined whether the identified characteristics were similarly associated with low-grade and high-grade DCIS detection.

METHODS

This retrospective cohort study included 1,750,002 digital screening mammograms (2145 screen-detected DCIS) performed in the Quebec breast cancer screening program between 2007 and 2015 inclusively. The associations between radiologists' and facilities' characteristics and (1) the DCIS detection rate, (2) the invasive detection rate, and (3) the odds of DCIS on invasive detection were assess. For statistically significant associations in the latter analysis, analyses stratified by DCIS grade were performed. Multivariable logistic regression with generalized estimating equations estimates to account for correlation among mammograms was used.

RESULTS

Compared to radiologists with recall rate between 5.0 and 9.9%, radiologists with recall rate between 15.0-19.9% and ≥ 20% reached a higher DCIS detection rate, with adjusted detection ratios of, respectively, 1.33 (95% confidence interval = 1.15-1.53) and 1.43 (95% confidence interval = 1.13-1.81). Increase in radiologist' recall rate was statistically significantly associated with an increase in detection of low/intermediate-grade DCIS (P < 0.001), while not in high-grade DCIS (P = 0.15).

CONCLUSIONS

A major determinant of DCIS detection is the radiologists' recall rate. Abnormalities referred by radiologists with higher recall rates should be identified in order to understand how to decrease recall rate while keeping an optimal DCIS and invasive detection rate.