What is the concern for a patient with a history of breast cancer in the right breast, status post (s/p) mastectomy, now presenting with complaints in the left breast, despite a normal left breast mammogram?

From the Guidelines

For a patient with a history of right breast cancer who underwent mastectomy and is now experiencing concerns about the left breast, but has a normal left breast mammogram, I recommend continued vigilant surveillance with regular clinical breast exams every 6 months and annual mammography of the remaining left breast. Despite the normal mammogram, any persistent or concerning symptoms in the left breast should be evaluated promptly with additional imaging such as ultrasound or MRI if needed. The patient should perform monthly breast self-examinations to become familiar with the normal feel of the remaining breast tissue. This surveillance approach is important because patients with a history of breast cancer in one breast have an increased risk of developing cancer in the contralateral breast. The normal mammogram is reassuring but does not eliminate the need for ongoing monitoring. Additionally, the patient should continue any prescribed adjuvant therapy for the original breast cancer, such as hormonal therapy if indicated, and maintain regular follow-ups with both the oncologist and breast surgeon to ensure comprehensive care, as recommended by the American Society of Clinical Oncology clinical practice guideline update 1. Annual mammography is the best imaging test for surveillance in this clinical scenario, with reduction of mortality compared with women with history of breast cancer who do not get annual mammography, as supported by the ACR practice parameters 1. The ASTRO and NCCN guidelines both recommend annual mammographic surveillance for women who have completed radiation therapy as part of breast conservation therapy, with the first imaging performed at 6 to 12 months 1. More frequent imaging of the ipsilateral affected breast beyond annual surveillance mammography, at 6-month intervals for the first 2 to 5 years, has also been studied, but two groups showed no benefits to this more frequent imaging 1. The addition of DBT to 2-D digital mammography or 2-D synthetic images in the surveillance of patients with prior breast cancer history has been shown to reduce recall rates and indeterminate findings, without significant change in cancer detection rate 1. Key points to consider in the management of this patient include:

• Regular clinical breast exams every 6 months
• Annual mammography of the remaining left breast
• Monthly breast self-examinations
• Prompt evaluation of any persistent or concerning symptoms in the left breast with additional imaging if needed
• Continuation of any prescribed adjuvant therapy for the original breast cancer
• Regular follow-ups with both the oncologist and breast surgeon to ensure comprehensive care.

From the FDA Drug Label

Tamoxifen reduces the occurrence of contralateral breast cancer in patients receiving adjuvant tamoxifen therapy for breast cancer The incidence of contralateral breast cancer is reduced in breast cancer patients (premenopausal and postmenopausal) receiving tamoxifen compared to placebo. In the NSABP B-14 trial, the annual rate of contralateral breast cancer was 8.0 per 1,000 patients in the placebo group compared with 5.0 per 1,000 patients in the tamoxifen group, at 10 years after first randomization.

The patient has a history of breast cancer in the right breast and has undergone a mastectomy. The patient is now complaining of issues with the left breast, but the mammogram is normal. Tamoxifen may be beneficial in reducing the risk of contralateral breast cancer. However, the decision to use tamoxifen should be based on an individual assessment of the benefits and risks of tamoxifen therapy 2.

• The patient's risk factors and medical history should be taken into account when deciding on tamoxifen therapy.
• The patient should be informed of the potential benefits and risks of tamoxifen therapy, including the reduction in contralateral breast cancer risk 2.
• A discussion of the patient's individual risk factors and the potential benefits and risks of tamoxifen therapy should be undertaken to determine the best course of treatment.

From the Research

Breast Cancer Diagnosis and Screening

• The patient has a history of breast cancer in the right breast, which was treated with mastectomy, and is now complaining of symptoms in the left breast 3.
• A normal mammogram result does not rule out the possibility of breast cancer, as mammography has a sensitivity of 54.5% (range 27%-86.8%) and specificity of 85.5% (range 62.9%-98.8%) 4.
• The combination of mammography and ultrasonography detects more breast cancer than mammography alone, with a risk ratio of 1.54 (95% CI 1.22 to 1.94) 5.

Diagnostic Performance of Imaging Modalities

• Magnetic Resonance Imaging (MRI) has the highest sensitivity (94.6%) and moderate specificity (74.2%) for breast cancer detection, while mammography has lower sensitivity (54.5%) and higher specificity (85.5%) 4.
• Ultrasound has a sensitivity of 67.2% and specificity of 76.8%, and its combination with MRI or mammography increases diagnostic accuracy 4.
• Contrast-enhanced mammography (CE-MM) and MRI (CE-MRI) have high sensitivity (90.5% and 91.5%, respectively) but lower specificity (52.6% and 64.7%, respectively) 4.

Management of Breast Complaints

• A structured approach to the evaluation and management of breast complaints is critical to distinguish benign disease from malignancy 6.
• High-risk breast lesions, such as atypical hyperplasia and lobular carcinoma in situ, require intensive surveillance and chemoprevention 6.
• Clinical examination, digital mammogram, ultrasound, and MRI can be used to determine postneoadjuvant pathologic tumor response in operable breast cancer patients, but their accuracy and predictive values vary 7.