Managing dual primary liver metastases from breast and colorectal cancers.

[INTRODUCTION] In the treatment of metastatic liver tumors, identifying the primary cancer is crucial for determining the appropriate treatment strategy. The management of colorectal liver metastases often centers around surgical resection, whereas breast cancer liver metastases are predominantly treated with chemotherapy. To our knowledge, this case represents a rare example of dual primary liver metastasis.

[CASE PRESENTATION] A 55-year-old female underwent systemic therapy with tamoxifen plus T-DM1 after right breast cancer resection 3 years ago. Two years ago, the patient developed simultaneous sigmoid colon cancer with liver metastasis. Due to liver damage from T-DM1, she initially underwent sigmoid colon resection, followed 2 months later by partial S5/8 resection and caudate lobectomy. S5/8 lesion was histologically diagnosed as colon cancer liver metastasis, while the caudate lobe lesion was breast cancer liver metastasis. 6 months after surgery, five liver metastases recurred, and the patient was diagnosed with liver metastatic recurrence of colorectal cancer. Six cycles of chemotherapy FOLFOX + Cetuximab were administered before surgery. The largest lesion of S5/8 shrunk, and the other four lesions were slightly enlarged. The histological examination confirmed the shrunken lesion as colorectal liver metastasis and the other lesions as breast cancer liver metastases.

[CONCLUSION] Although radiological differentiation of metastatic liver lesions is challenging, chemotherapy response and tumor localization can aid in diagnosis. Multi-disciplinary cooperation is essential in determining treatment strategies for dual primary liver metastases.