Mammography. The role of mammography after BCT is close surveillance of the treated breast for clinically occult recurrent BC as well as screening of the contralateral breast. Patients typically undergo their first posttreatment mammogram 6–12 months after completion of radiation treatment. The degree of oedema and distortion that is seen on the mammogram can vary significantly from one patient to another. At the time of the baseline mammogram after completion of treatment, some patients will have extensive oedema, trabecular thickening and architectural distortion, while other patients will have minimal mammographic changes. These posttreatment changes tend to be maximal at about 6 months after treatment and may pose a challenge to the breast imager in detecting recurrent disease. On subsequent mammograms, the posttreatment changes may remain stable but usually decrease in prominence over time. Therefore, any new or worsening finding on subsequent screening mammography, such as new calcifications, new mass or increasing architectural distortion, needs to be viewed cautiously and evaluated carefully for recurrent disease [10].

Ultrasound. For the evaluation of new or suspicious mammographic masses as well as clinically palpable findings, breast ultrasound is an essential tool that plays a complementary role to mammography and physical examination. In the evaluation of palpable breast masses, sonography is particularly helpful, since the mammographic evaluation can be limited due to the posttreatment changes. In patients presenting with palpable breast masses, prospective and retrospective studies have reported the negative predictive value of combined mammography and sonography to be very high, approaching 100 %. In addition, if a lesion is visible on ultrasound, a minimally invasive core-needle biopsy or fine-needle aspiration can be performed under sonographic guidance [11].

Breast MRI is well known to detect mammographically occult BC. Unlike mammography and sonography, MRI dynamically evaluates the breast tissue. In addition to assessing the morphology of the breast lesions, the vascularity of any lesions may be evaluated after intravenous contrast enhancement (see Sect. 5.​3). Lesion enhancement is based on the number and the permeability of the blood vessels.

There is, however, some overlap in enhancement characteristics seen in benign and malignant lesions. In women with equivocal mammographic findings after breast-conservation treatment, the enhancement pattern on contrast-enhanced MRI can be helpful in differentiating posttreatment scar from recurrent cancer. Breast MRI can also detect mammographically occult local recurrence in the breast BCT [12, 13].

Since local or regional recurrence is a marker of increased aggressiveness, all patients experiencing a relapse, both local and regional, have to undergo proper systemic workup to rule out the presence of synchronous distant metastases. In addition to a complete history and physical exam, patients should have a CT of the chest/abdomen/pelvis and a bone scan. On the other hand, CT should be considered in any patient with new onset pain, paralysis, paraesthesia or lymphoedema, even in the absence of palpable disease. PET scans are used in uncertain situations or when the results of the CT or bone scan are equivocal.

For a woman, learning that she has a recurrent BC may be harder than dealing with the initial diagnosis. An appropriate intervention, including psycho-education, is needed for patients diagnosed with first recurrence in order to detect and manage psychological distress.