The epidemiology of metaplastic breast cancer: A review of 2,500 cases from the national cancer database.

Abstract

1570 Background: Metaplastic breast cancer (MBC) is a rare, aggressive, sarcomatoid breast cancer that was first described in 1973 but only became recognized as a histologically distinct entity in 2000. Given the paucity of data on the epidemiology of MBC, we performed a population-based analysis to delineate sociodemographic and clinicopathological characteristics associated with increased likelihood of MBC diagnosis. Methods: Adult female breast cancer patients with stage I-III MBC and non-MBC histology diagnosed between 2010 and 2013 were identified in the National Cancer Database (NCDB). Multivariate logistic regression was used to identify factors associated with diagnosis of MBC, and Cox proportional hazards modeling was used to estimate the effect of MBC on overall survival. Results: 2,451 MBC and 568,057 non-MBC patients were identified. After adjusting for receptor status (ER, PR, HER2), age, stage, grade, and treatment variables, MBC patients had worse survival than non-MBC patients (HR 1.45, p < 0.001). Compared to non-MBC patients, a higher proportion of MBC patients were non-Hispanic black (16.7% vs 10.5%), had an annual income < $35k (29.0% vs 25.5%), had lower high school completion rates (36.7% vs 33.9%), were treated at academic centers (35.5% vs 30.8%), and had government-sponsored insurance (48.8% vs 43.7%, all p < 0.01). MBC diagnosis was more likely in patients with triple-negative breast cancer (OR 20.71), higher clinical T stage (cT4 vs cT1: OR 6.18), and lower clinical N stage (cN1 vs cN0: OR 0.38, all p < 0.001). MBC patients were also more likely to be diagnosed based on pathology from their first operation rather than preoperatively (OR 1.41, p < 0.001). Conclusions: Black women and women of low socioeconomic status were at increased risk for diagnosis with MBC. Though MBC was more likely to be treated at academic centers, MBC was less likely to be diagnosed prior to surgical intervention. Many of the sociodemographic factors associated with MBC have also been associated with triple-negative breast cancer. Additional research is needed to determine the contribution of sociodemographic factors to the epidemiology of MBC independent of receptor status.

Challenges in Managing Metaplastic Breast Cancer-Referencing an Indexed Case and a Ten-Year Experience in a Developing Country

“…Notably, as compared to other breast cancer subtypes, axillary nodal involvement are only found in 8-40% of cases and haematogenous spread to the bone and lungs is more common, as compared to the lymphatic route [4].…”

“…It commonly affects women in the age 49-59 group, with most patients presenting with larger size and more advanced tumours, compared to those with invasive ductal carcinoma, which is the most common type of breast cancer [3]. In an epidemiological study by the National Cancer Database by Campbell et al [4] women of African descent and low socioeconomic status were found to be at increased risk for diagnosis.…”

“…Triple negative hormone receptor status, however, is also more likely to be associated with theaforementioned sociodemographic factors [4].…”

“…Diagnosis of this condition is made via traditional modalities such as mammogram, ultrasound, MRI and biopsy, but the associated findings do differ based on the tumour makeup, which is variable and makes diagnosis difficult [3]. It has been shown that metaplastic breast cancer is less likely to be diagnosed correctly prior to surgical intervention, due to its mixed histological makeup [4]. The diagnosis is made via morphology for the carcinomas with a squamous component or a pure squamous carcinoma, and via immunohistochemistry for those with sarcomatoid or spindle cell carcinoma, which coexpress cytokeratin and vimentin [5].…”

“…Metaplastic breast cancer carries a poor prognosis. In a population-based analysis of 250 patients, it was demonstrated that overall survival (OS) was worse than with invasive ductal, and that the outcome is not influenced by hormone receptor status [4]. Additionally, a study using the SEER Database, reported that patients with metaplastic breast cancer have shorter disease-free survival (DFS) than those with invasive ductal carcinoma [15].…”