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The local extent of breast cancer is often detected only at surgery, but modern imaging may be able to give us this information preoperatively instead
An 81 year old woman was referred to a multidisciplinary breast clinic with a lump in her right breast. Such patients undergo “triple” assessment—clinical examination, imaging, and, if necessary, needle biopsy. On clinical examination she had a mass in the upper outer quadrant, which was suspected to be an underlying carcinoma.
It is usual practice for patients over 35 years with discrete breast lumps to undergo mammography and ultrasound. In patients under 35 years, ultrasound is the first line investigation.
Mammography has been evaluated more extensively than any other imaging technique and remains a mainstay of the diagnosis of breast cancer. Reported sensitivity in detecting palpable breast cancer is 80-90%,1 but it is lower in patients with dense breast parenchyma. A normal mammogram can be seen in the presence of a palpable breast cancer, so national guidance recommends that all breast units should provide triple assessment clinics for symptomatic women rather than an open access imaging service for general practitioners.2
Targeted breast ultrasound is the most useful test when evaluating a breast lump. It can distinguish between “lumpiness” caused by a ridge of normal dense parenchyma, a fluid filled cyst, or a solid mass. In expert hands, it can also help characterise solid lesions—its negative predictive value for correctly classifying benign masses is up to 99.5% and sensitivity for identifying malignancy is up to 98.4%.3
The above tests cannot replace histological confirmation, however, and in the United Kingdom, patients with a clinically suspicious or focal solid lesion routinely have a needle biopsy to establish a diagnosis. Core biopsy, with its higher sensitivity and specificity (96.7% and 98.7%), is replacing fine needle aspiration cytology (sensitivity 83.1%; inadequate rate 12.8%).4 Ultrasound guidance optimises targeting accuracy.
If a diagnosis of breast cancer is made, definitive treatment (usually surgery) can be planned. In some patients, histopathological analysis of surgical specimens shows that disease is more extensive than first suggested by clinical examination and imaging. Further treatment may then be needed, such as margin re-excision, mastectomy, or additional axillary surgery. Can modern breast radiology provide more accurate information about local staging preoperatively? Two additional imaging and intervention techniques show potential.
Dynamic contrast enhanced breast magnetic resonance imaging is the most sensitive examination available for determining the extent of invasive breast cancer—it detects additional unsuspected tumour sites in 16% of patients.5 The information it provides on tumour size and extent can help determine whether breast conservation or mastectomy is the best surgical option.6 The technique is expensive however. In addition, UK machines are overloaded with work, and we do not know which patients with newly diagnosed breast cancer would benefit most from magnetic resonance imaging. A large UK multicentre trial is currently trying to answer this question.7
Sentinel lymph node biopsy, with its high accuracy and low morbidity, is now the surgical method of choice for staging the axilla in patients with invasive breast cancer. The sentinel lymph node is identified at surgery after injecting radioisotope colloid and blue dye into the breast. Patients with malignancy in the sentinel lymph node will need a second operation to clear their remaining axillary nodes. Ultrasound and needle biopsy of the axilla before surgery can identify 42-63% of patients with involved lymph nodes, who may then have therapeutic surgery of both breast and axilla as a single procedure.8 9
Mammography detected an area of parenchymal deformity corresponding to the palpable lump. A further, impalpable, suspicious mass was also seen in the left breast (fig 11).). Ultrasound confirmed that both lesions were solid, with features suggestive of malignancy. Bilateral core biopsies guided by ultrasound confirmed an invasive lobular carcinoma in the right breast and an invasive ductal carcinoma in the left breast. Our policy is to perform magnetic resonance imaging in patients with invasive lobular carcinoma, which may have a permeative growth pattern, as it is difficult to determine the extent of disease with standard imaging techniques. Magnetic resonance imaging confirmed the size and position of both known tumours but also showed extra foci in each breast (fig 22).). Bilateral axillary ultrasound and core biopsy found no evidence of malignancy. On the basis of these investigations the patient had bilateral mastectomies and sentinel lymph node biopsies at a single operation. Histology confirmed multifocal invasive lobular carcinoma in the right breast and invasive ductal carcinoma in the left breast, together with bilateral high grade ductal cancer in situ. One of the two sentinel lymph nodes on the right contained a 0.2 mm diameter micrometastasis; the remainder were free of tumour. After discussion with the patient it was decided that no further axillary surgery was necessary.
Contributors: PB received the commission for the article and selected the patient. The literature was searched by PB and RS. PB wrote the initial draft of the paper. RS reviewed and edited it and both authors revised it. PB is guarantor.
Competing interests: None declared.