Accuracy of mammography and ultrasound for detecting breast cancer at a breast care clinic in Karachi, Pakistan.

Abstract

Objectives: Mammography is an important screening tool which can effectively detect breast cancer earlier before it becomes palpable on breast self examination. The main objective of this study was to determine screnning accuracy of  mammography and ultrasound (US) in a local population.

Material and Methods: This prospective analysis included 1104 women (median age 40; 11-81 years) attended a breast care clinic at Karachi Institute of Radiotherapy and Nuclear Medicine (KIRAN), Karachi, Pakistan, for screening (559) or presented with palpable breast lump (545). As per American Cancer Society (ACS) guidelines 2003, mammogram and US was performed. Fine needle aspiration cytology (FNAC) was subjected in 217 women with Breast Imaging Reporting And Data System (BIRADS) IV/V, high risk patients with III on mammography and with suspicious US findings, while women with normal to benign looking US, BIRADS I, II and III were followed after 12 ±3 months.

Results: Mammography was performed on 564 (51%) women and classified as BIRADS I in 227 (40%), II in 110 (20%), III in 53 (9%), IV in 130 (23%) and as V in 44 (8%). Remaining 540 (49%) women were subjected for breast US, among them 408 (76%) were absolutely normal, 97 (18%) revealed benign pathology and 35 (6%) had suspicious findings. On FNAC, 206/217 (19%; incidence rate=1:6 with 95% CI of 1:6 to 1:5, p <0.001) were diagnosed as breast cancer. Sensitivity, Specificity, Positive predictive value (PPV) and Negative Predictive Value (NPV) were 80.47%, 73.07%, 64.79% and 85.86% for mammogram; 86.84%, 99.6%, 94.29% and 99.01% for US respectively. The sensitivity, specificity, PPV and NPV of US as compared to mammogram was statistically significant i-e. p=0.005 (χ²=7.701), p<0.0001 (χ²=159.58), p<0.0001 (χ²=144.05) and p<0.0001 (χ²=65.22) respectively.

Conclusion: We concluded that US should be considered as a primary screening tool in younger population and as an adjunct to mammogram in elder women to minimize the chances of missing diagnosis of breast cancers in relatively younger women.