Clinical characteristics and outcome of bone-only metastasis in inflammatory and noninflammatory breast cancers

Background Inflammatory breast cancer is a rare and aggressive presentation of breast cancer. Bone is a common metastatic site in breast cancer, and bone-only metastatic disease is clinically considered to have a better prognosis than visceral metastasis. However, bone-only metastasis in IBC (bone-only IBC) has not been compared with bone-only metastasis in non-IBC (bone-only non-IBC) in terms of clinical features and outcome. Because of the intrinsically aggressive nature of IBC, we hypothesized that bone-only IBC has a poorer prognosis than does bone-only non-IBC.

Patients and Methods We retrospectively identified patients with stage III primary diagnosed breast cancer who, between January 1997 and December 2012, had a first recurrence located only in the bone. Among the 197 patients that we defined as a study cohort, 50 patients had IBC and 147 patients had non-IBC. Progression-free survival (PFS) and overall survival (OS) from the date of recurrence were estimated using the Kaplan-Meier method, and patient characteristic groups were compared using the log-rank test.

Results OS did not differ significantly between the 2 groups (P =.2467), but a shorter PFS was seen in patients with bone-only IBC than in patients with bone-only non-IBC (P =.0357). Among patients with estrogen receptor (ER)-positive disease, a much shorter PFS was seen in bone-only IBC than in bone-only non-IBC (P =.0159).

Conclusion Bone-only IBC has a poorer prognosis than does bone-only non-IBC, particularly in those with ER-positive tumors. We might need to consider more aggressive intervention (eg, chemotherapy) for IBC patients with ER-positive bone-only metastatic disease.