Table 5. Selected Studies of Aldehyde Dehydrogenase 1 (ALDH1) Expression in Breast Tissue.
| Study (Year) | Assessment of ALDH1 Positivity | Frequency of ALDH1 Positivity | Study Findings |
|---|---|---|---|
| Kunju et al8 (2011) | ≥5% epithelial cells with cytoplasmic staining. | Case-control study of benign breast biopsies in women who subsequently developed breast cancer versus those who did not develop breast cancer. | Epithelial and stromal ALDH1 expression associated with increased risk of future breast cancer. |
| Expanded stromal staining defined as extension beyond intralobular stroma into interlobular stroma. | 43% of cases. | ||
| Scoring based on foci with maximal staining. | 13% of controls. | ||
| Ginestier et al9 (2007) | Any cytoplasmic staining (ALDH1-positive cases noted to have only 5% cells expressing stain). | 19% University of Michigan cases. | ALDH1-positivity associated with high-grade, estrogen receptor–negative tumors and poor prognosis. |
| 30% Institut Paoli-Calmettes cases. | |||
| Nalwoga et al10 (2010) | Combination of ALDH1 staining intensity and proportion of cells staining positive. | 48% of Ugandan breast cancer cases. | ALDH1 expression associated with high-grade tumors and estrogen receptor–negativity |
| Zhou et al32 (2010) | N/A | N/A | Meta-analysis of cancer stem cell studies in breast cancer; studies using ALDH1 as a cancer stem cell marker demonstrated strongest association between cancer stem cells and poor prognosis. |
| Neumeister et al33 (2010) | N/A | N/A | Multiplexed staining for ALDH1 coexpressed with CD44 as a marker of cancer stem cells was associated with poor prognosis. |
| Park et al34 (2010) | ≥10% ALDH1 staining | 9% pure IDC | ALDH1 positivity correlated with basal-like and HER2/neu-overexpressing tumors. |
| 6% IDC plus DCIS | |||
| 3% DCIS plus microinvasion | |||
| 3% pure DCIS | |||
| Charafe-Jauffret et al35 (2010) | Combination of ALDH1 staining intensity and proportion of cells staining positive | 31% of inflammatory breast cancer cases | ALDH1-positivity associated with poor prognosis among cases of inflammatory breast cancer. |
| Yoshioka et al36 (2011) | Any cytoplasmic staining in cancer cells | 26% IDC | ALDH1 expression associated with poor prognosis in node-positive breast cancer. |
| 14% DCIS | |||
| Resetkova et al37 (2010) | Combination of ALDH1 staining intensity and proportion of cells staining positive. | 18% all cancers | Tumor ALDH1 expression correlated with basal-like tumors. |
| 39% basal tumors | Stromal ALDH1 expression correlated with improved outcome. | ||
| Heerma van Voss et al38 (2011) | Combination of ALDH1 staining intensity and proportion of cells staining positive. | 78% BRCA1 mutation-associated cancers and 41.5% sporadic cancers with tumoral expression. | BRCA1 mutation-associated cancers more likely to be ALDH1-positive. |
| 58.5% BRCA1 mutation-associated cancers and 43.9% sporadic cancers with stromal expression. |
Abbreviations: DCIS, ductal carcinoma in situ; IDC, invasive ductal carcinoma; N/A, not applicable.