Intracystic papillary carcinoma: a review of 917 cases

BACKGROUND: Intracystic papillary carcinoma (IPC) is an uncommon breast neoplasm. To the authors' knowledge there are limited data regarding its epidemiology and only small studies focusing on outcomes. By using a large, population-based database, this study aimed to identify specific characteristics of patients with IPC, investigate its natural history, and determine its long-term prognosis. METHODS: The California Cancer Registry (CCR), a population-based registry, was reviewed from the years 1988 through 2005. The data were analyzed with regard to patient sex, age at presentation, tumor stage, and overall survival. Cumulative relative actuarial survival was determined using a Berkson-Gage life table method. The CCR classifies IPC as either in situ (CIS) or invasive, as determined by the local pathologist. RESULTS: A total of 917 cases of IPC were identified. Approximately 47% of cases (n = 427) were CIS, whereas 53% of cases had invasion (n = 490). The majority of the invasive cases were localized at the time of diagnosis (89.6%; n = 439). At 10 years, patients with CIS and invasive disease had a similar relative cumulative survival (96.8% and 94.4%; P = .18). CONCLUSIONS: IPC is a rare disease. There is no apparently significant difference in the long-term survival of patients in the 2 histologically derived subgroups of IPC. There is an excellent prognosis for patients diagnosed with IPC regardless of whether the tumor is diagnosed as in situ or invasive. Clinicians should keep this in mind when planning surgical and adjuvant treatments. Sentinel lymph node biopsy may be a prudent way to evaluate axillary involvement in patients with IPC.