Abstract
BackgroundAlthough the invasive lobular carcinoma (ILC) is the second most frequent histologic subtype in Western countries, its incidence is much lower in Asia, and its characteristics are less well known.MethodsWe assessed the clinical characteristics and outcomes of 83 Korean patients (2.8%) with ILC for comparison with 2,833 (97.2%) with the invasive ductal carcinoma (IDC), including 1,088 (37.3%) with the luminal A subtype (LA-IDC).ResultsThe mean age of all patients was 48.2 years, with no significant differences among the groups. Compared to IDC, ILC showed a larger tumor size (≥T2, 59.8% vs. 38.8%, P = 0.001), a lower histologic grade (HG 1/2, 90.4% vs. 64.4%, P < 0.001), more frequent estrogen receptor positive (90.4% vs. 64.4%, P < 0.001), progesterone receptor positive (71.1% vs. 50.1%, P < 0.001) and HER2 negative (97.5% vs. 74.6%, P < 0.001) status, and lower Ki-67 expression (10.3% ± 10.6% vs. 20.6% ± 19.8%, P < 0.001), as well as being more likely to be of the luminal A subtype (91.4% vs. 51.2%, P < 0.001). Six (7.2%) ILC and 359 (12.7%) IDC patients developed disease recurrence, with a median follow-up of 56.4 (range 4.9-136.6) months. The outcome of ILC was close to LA-IDC (HR 0.77 for recurrence, 95% CI 0.31-1.90, P = 0.57; HR 0.75 for death, 95% CI 0.18-3.09, P = 0.70) and significantly better than for the non-LA-IDC (HR 1.69 for recurrence, 95% CI 1.23-2.33, P = 0.001; HR 1.50 for death, 95% CI 0.97-2.33, P = 0.07).ConclusionsILC, a rare histologic type of breast cancer in Korea, has distinctive clinicopathological characteristics similar to those of LA-IDC.
Highlights
The invasive lobular carcinoma (ILC) is the second most frequent histologic subtype in Western countries, its incidence is much lower in Asia, and its characteristics are less well known
Compared to invasive ductal carcinoma (IDC), ILC showed a larger tumor size (≥T2, 59.8% vs. 38.8%, P = 0.001), a lower histologic grade (HG 1/2, 90.4% vs. 64.4%, P < 0.001), more frequent estrogen receptor positive (90.4% vs. 64.4%, P < 0.001), progesterone receptor positive (71.1% vs. 50.1%, P < 0.001) and human epidermal growth factor receptor-2 (HER2) negative (97.5% vs. 74.6%, P < 0.001) status, and lower Ki-67 expression (10.3% ± 10.6% vs. 20.6% ± 19.8%, P < 0.001), as well as being more likely to be of the luminal A subtype (91.4% vs. 51.2%, P < 0.001)
The outcome of ILC was close to Luminal A (LA)-IDC (HR 0.77 for recurrence, 95% confidence interval (CI) 0.31-1.90, P = 0.57; hazard ratio (HR) 0.75 for death, 95% CI 0.18-3.09, P = 0.70) and significantly better than for the non-luminal A subtype of IDC (LA-IDC) (HR 1.69 for recurrence, 95% CI 1.23-2.33, P = 0.001; HR 1.50 for death, 95% CI 0.97-2.33, P = 0.07)
Summary
The invasive lobular carcinoma (ILC) is the second most frequent histologic subtype in Western countries, its incidence is much lower in Asia, and its characteristics are less well known. It is more likely to occur in older patients, be larger in size, be estrogen receptor (ER) and progesterone receptor (PgR) positive and have low to absent human epidermal growth factor receptor-2 (HER2) expression [9,10]. Both ILC and IDC subtypes have received the same treatment, Recently, classification of breast cancers by gene expression profiling into particular subtypes has become established [12]. The relative distributions of these four immunohistochemically defined subtypes in the lobular lesions have yet to be established in detail
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