Breast cancer is the most common cancer in our hospital, occurred in 25.8% of women's cancers (1,010 cases in 2007). Since there is no effective way to prevent breast cancer, the best effort is to treat the disease at its earliest stage. Breast imaging has proven to be the most appropriate method to detect the lesion, which includes mammography, ultrasound, MRI and RNS. Concerning the cost effectiveness and availability, mammography (mammo) and ultrasound (US) are our studies of choice.
Mammography has limitations in detection and evaluation of breast lesions in mammographic dense breasts, palpable mass in young women, pregnant and lactate breasts, acute inflammation, post-operation, trauma, male gynecomastia and assessment of augmented breasts. Analysis of breast tissue composition in 168,920 mammo shows 75% of Thai breasts are difficult breasts (heterogenously dense and extremely dense). The mass are notified as round, oval, lobular, which are less significant; irregular, microlobular and speculated, which are more suspicion. There might be associated findings, such as the presence of microcalcifications and architectural distortion.
Ultrasound is much more informative in evaluation of breast mass, for its shape (round, oval or irregular), orientation (parallel, non-parallel), margin (circumscribed or not circumscribed: indistinct, angular, microlobulated or speculated), lesion boundary (abrupt interface or echogenic halo), echo pattern (anechoic, hypoechoic, isoechoic, hyperechoic and complex), posterior acoustic features (no posterior acoustic features, enhancement, shadowing and combined pattern), surrounding tissue (in ducts, straightening or thickening of cooper's ligament, edema, skin thickening US fug, architectural distortion), vasculature and other specific findings. Analysis of each US finding was made. Of 24,741 mammo with US, US can detect 141 cancers in mammo negative (182 US BIRADS 4, 32 US BIRADS 5). Concerning detection of breast mass, there were 13,109 cases that both mammo & US were positive, 14,220 cases that were positive in US only (negative in mammo).
US of axillary adenopathy is superb, giving more internal architecture details, pathology and includes more nodes than it is seen by mammo. FNA of the abnormal node can be performed in one setting, which is far better than to search and do excisional biopsy of sentinel lymph node, performed in the operating room. Normal nodes was also studied.
US has limitation in microcalcifications, esp. those with no associated mass. However, if the lesion is extensive, US may show where the lesion is and US guided CNB can be performed, with proven specimen film to show the presence of the microcalcifications. Of 39,830 screening, there were 84 breast cancers and 19 cases (22.62%) had microcalcifications alone, which were negative in US, and 106 cases (6.02%) of 1761 cancers in 22,442 diagnostic cases had microcalcifications alone.
We had compared the results of mammography with pathology and US result of each pathology, as well as US result comparing with pathology and mammography result. The outcome of using both studies together yielded a much better impressive results that when it looks benign, it's true benign in 94.9%, probably benign is benign in 88.57%, indeterminate is 50 +/- 3.49% and malignant is true malignant in 95.78%
US may have drawback in operator dependent. This is solved by using automated breast US, which is very quick, provides multiplanar image, very high resolusion, reproducible for comparison study.