Patterns of metastatic breast carcinoma: influence of tumour histological grade

To assess if the pattern of metastatic spread of carcinoma of the breast varies according to tumour histological grade.

The clinical details, histological features of the primary tumour, and imaging findings at presentation of patients with metastatic breast cancer have been recorded prospectively since 1997. The pattern of metastatic spread, age at metastasis, metastasis-free interval (MFI), and length of survival with metastases were analysed by tumour grade.

There was a significant association between histological high-grade tumours and high frequency of intra-pulmonary metastases (p=0.013); liver metastases (p=0.039); para-aortic lymphadenopathy (p=0.022) and metastatic presentation under 50 years of age (p=0.003). A significant correlation was also demonstrated between histological low-grade tumours and increased frequency of pleural disease (p=0.020); increased frequency of bone metastases (p=0.004); prolonged MFI (MFI>5 years; p<0.0001); and increased length of survival (p<0.0001).

There is a correlation between patterns of metastatic spread and tumour histological grade. This partly explains the negative prognostic value of high tumour grade, as metastases from grade 3 tumours more commonly occur at sites associated with a worse prognosis. This finding may also prove useful in interpreting imaging in patients who have a history of breast cancer and undergo subsequent imaging because of new symptoms.