A Study of Lobular Carcinoma of the Breast Based on the Third National Cancer Survey in the United States of America

HER2 Positive and HER2 Negative Classical Type Invasive Lobular Carcinomas: Comparison of Clinicopathologic Features

Human epidermal growth factor receptor 2 (HER2) positive (+) classical type invasive lobular carcinoma (cILC) of the breast is extremely rare and its clinicopathologic features have not been well characterized. We compared features of HER2(+) and HER2 negative (-) cILCs. A total of 29 cases were identified from the clinical database at our institution from 2011-2019; 9 were HER2(+) cILC tumors and 20 were HER2(-) cILC tumors. The results reveal that HER2(+) cILC group had significantly increased Ki-67 expression and reduced estrogen receptor (ER) expression compared to HER2(-) cILC group (both p < 0.05). In addition, HER2(+) cILCs tended to be diagnosed at a younger age and more common in the left breast, and appeared to have a higher frequency of nodal or distant metastases. These clinicopathologic features suggest HER2(+) cILC tumors may have more aggressive behavior than their HER2(-) counterpart although both groups of tumors showed similar morphologic features. Future directions of the study: (1) To conduct a multi-institutional study with a larger case series of HER2(+) cILC to further characterize its clinicopathologic features; (2) to compare molecular profiles by next generation sequencing (NGS) assay between HER2(+) cILC and HER2(-) cILC cases to better understand tumor biology of this rare subset of HER2(+) breast cancer; and (3) to compare molecular characteristics of HER2(+) cILC and HER2(+) high grade breast cancer in conjunction with status of tumor response to anti-HER2 therapy to provide insight to management of this special type of low grade breast cancer to avoid unnecessary treatment and related toxicity.

Breast Cancer: Primary Tumor Characteristics Related to Lymph Node Involvement

From November 1st 1977 to August 31st 1978, 842 consecutive patients with operable breast cancer were observed at the National Cancer Institute of Milan. Characteristics of the primary tumor and the status of regional lymph nodes were evaluated at clinical and postsurgical examination: it was found that qualitative characteristics of the primary were properly defined by clinicians, who usually overestimated maximum diameter of the primary. The status of regional lymph nodes is not reliable at clinical examination: 34.5 % of clinically uninvolved nodes were found to contain metastatic growth at histologic examination. Age of patients, maximum diameter of the primary, histologic type and quadrant of origin of the primary tumor were significantly related to the frequency of regional node metastases. Multifactorial analysis showed that the last three factors were independent variables, while age, which is significant by itself, loses importance when adjusted by at least one of the other three factors. Frequency of extension of node metastases beyond the lymph node capsule was found to be related to the number of involved nodes: maximum diameter, histologic type and site of origin are significantly related to the frequency of extracapsular invasion. This study confirms that the evaluation of the status of regional lymph nodes is not reliable at clinical examination and indicates that characteristics of the primary may be useful in predicting regional lymph node involvement. The direct correlation between the number of involved nodes and the frequency of infiltration beyond the capsule suggests that prognosis of patients with positive nodes depends more on this factor than on the number of involved nodes.

Estrogen switches pure mucinous breast cancer to invasive lobular carcinoma with mucinous features

Mucinous breast cancer (MBC) is mainly a disease of postmenopausal women. Pure MBC is rare and augurs a good prognosis. In contrast, MBC mixed with other histological subtypes of invasive disease loses the more favorable prognosis. Because of the relative rarity of pure MBC, little is known about its cell and tumor biology and relationship to invasive disease of other subtypes. We have now developed a human breast cancer cell line called BCK4, in which we can control the behavior of MBC. BCK4 cells were derived from a patient whose poorly differentiated primary tumor was treated with chemotherapy, radiation and tamoxifen. Malignant cells from a recurrent pleural effusion were xenografted in mammary glands of a nude mouse. Cells from the solid tumor xenograft were propagated in culture to generate the BCK4 cell line. Multiple marker and chromosome analyses demonstrate that BCK4 cells are human, near diploid and luminal, expressing functional estrogen, androgen, and progesterone receptors. When xenografted back into immunocompromised cycling mice, BCK4 cells grow into small pure MBC. However, if mice are supplemented with continuous estradiol, tumors switch to invasive lobular carcinoma (ILC) with mucinous features (mixed MBC), and growth is markedly accelerated. Tamoxifen prevents the expansion of this more invasive component. The unexpected ability of estrogens to convert pure MBC into mixed MBC with ILC may explain the rarity of the pure disease in premenopausal women. These studies show that MBC can be derived from lobular precursors and that BCK4 cells are new, unique models to study the phenotypic plasticity, hormonal regulation, optimal therapeutic interventions, and metastatic patterns of MBC.

Invasive Lobular Carcinoma of the Breast

Invasive lobular carcinoma of the breast is a distinct histologic type with specific clinical, radiologic, and microscopic features, which is increasing in incidence in the Western World. Routine pathologic prognostic factors, including grade, lymph node stage, and size are of significance in predicting outcome in this group of patients who, overall, have survival comparable to those with other subtypes of breast cancer. Variants, however, are seen and these, as well as other standard factors such as histologic grade, have prognostic significance and should be recorded in pathology reports.

Infiltrating lobular carcinoma of the breast: tumor characteristics and clinical outcome

INTRODUCTION

Invasive lobular carcinoma (ILC) comprises approximately 10% of breast cancers and appears to have a distinct biology. Because it is less common than infiltrating ductal carcinoma (IDC), few data have been reported that address the biologic features of ILC in the context of their clinical outcome. In the present study we undertook an extensive comparison of ILC and IDC using a large database to provide a more complete and reliable assessment of their biologic phenotypes and clinical behaviors.

METHODS

The clinical and biological features of 4140 patients with ILC were compared with those of 45,169 patients with IDC (not otherwise specified). The median follow-up period was 87 months.

RESULTS

In comparison with IDC, ILC was significantly more likely to occur in older patients, to be larger in size, to be estrogen and progesterone receptor positive, to have lower S-phase fraction, to be diploid, and to be HER-2, p53, and epidermal growth factor receptor negative. It was more common for ILC than for IDC to metastasize to the gastrointestinal tract and ovary. The incidence of contralateral breast cancer was higher for ILC patients than for IDC patients (20.9% versus 11.2%; P < 0.0001). Breast preservation was modestly less frequent in ILC patients than in IDC patients. The 5-year disease-free survival was 85.7% for ILC and 83.5% for IDC (P = 0.13). The 5-year overall survival was 85.6% for ILC and 84.1% for IDC (P = 0.64).

CONCLUSION

Despite the fact that the biologic phenotype of ILC is quite favorable, these patients do not have better clinical outcomes than do patients with IDC. At present, management decisions should be based on individual patient and tumor biologic characteristics, and not on lobular histology.

Infiltrating lobular carcinoma. Is it different from infiltrating duct carcinoma?

BACKGROUND

Infiltrating lobular carcinomas (ILC) represent approximately 10% of all breast cancers. The literature is mixed regarding their prognosis when compared with infiltrating duct carcinomas (IDC). There are few data regarding the treatment of ILC with radiation therapy.

METHODS

The clinical, pathologic, laboratory, and survival data of 161 patients with ILC were compared with the data of 1138 patients with IDC.

RESULTS

ILCs were larger, more difficult to excise completely, and more difficult to diagnose clinically. All prognostic factors measured were more favorable for ILC. Nodal positivity for ILC was 32%, compared with 37% for IDC (P = 0.22). The 7-year disease-free Kaplan-Meier survival (DFS) was 74% for patients with ILC and 63% for patients with IDC (P < 0.03). The 7-year breast cancer specific survival (BCSS) was 83% for patients with ILC and 77% for patients with IDC (P < 0.04). Selected patients with smaller lesions were treated with excision and radiation therapy. Patients with ILC treated with radiation therapy had a better DFS and BCSS than did patients with IDC treated with radiation therapy.

CONCLUSIONS

ILCs often are homogeneous, small cell tumors of low nuclear grade. Their desmoplastic reaction may be absent or less marked than that of IDC, making them more difficult to palpate and to visualize mammographically. Despite this, they can be treated successfully with either mastectomy or excision and radiation therapy.

On the possible role of involution in the natural history of breast cancer

Although the importance of the relationship between age and cancer incidence rates is recognized universally, little attention seems to have been paid to the relationship between the physiologic aging process in the breast and breast cancer risk. The natural history of breast cancer was examined in the context of involution of the breast, and it was proposed that the rate and extent of involution might be important determinants of breast cancer risk. It was concluded that additional studies to characterize the process of involution better histopathologically and to examine the associations between the rate and extent of involution and breast cancer risk are warranted.

Management and survival of female patients with "minimal" breast cancer: as observed in the long-term and short-term surveys of the American College of Surgeons

The American College of Surgeons' long-term breast cancer survey in 1978 included 16,894 pathologically confirmed carcinomas of the female breast, in situ or infiltrative, with negative or positive nodes. Of these, 1.9% were in situ carcinoma of any size, and 8.4% were minimal invasive carcinomas 1 cm or less in diameter. No significant difference was found between the survival of patients with in situ tumors of any size and minimal invasive tumors with negative axillary nodes measuring 1 cm or less in diameter. In patients with invasive tumors with negative axillary lymph nodes, no statistically significant difference was found in survival of patients with tumors of 0.5 cm or less, when compared either with survival of patients with tumors measuring 0.6-1.0 cm. Recurrence rates observed in those groups were not statistically significant. Among 157 patients with invasive tumors measuring 0.5 cm or less, 23.0% presented with axillary lymph node metastasis. Tumors measuring 0.6 to 1.0 cm showed 20.9% positive axillary nodes in 964 patients. Statistically significant differences in survival and recurrence rates were achieved only for invasive tumors smaller than 1 cm. Survival and recurrence rates were significantly better (P less than 0.001) in patients with minimal invasive cancer with negative axillary nodes (P less than 0.001) than rates of patients with invasive tumors larger than 1 cm and with negative lymph nodes. Similar statistical results were obtained for patients with positive axillary nodes only for invasive cancers smaller than 1 cm. However, survival and recurrence rates observed in invasive cancers of 1 cm or less with positive axillary nodes suggest that tumor size alone cannot be used as the only defining criterion for minimal invasive breast cancer. Only the status of axillary nodes may determine whether a small invasive tumor below 1 cm may be considered as minimal breast cancer.