Endocrine-responsive lobular carcinoma of the breast: features associated with risk of late distant recurrence

Fine-Tuning Adjuvant Endocrine Therapy for Early-Stage Breast Cancer: An Expert Consensus on Open Issues for Future Research

After decades of research, improving the efficacy of adjuvant endocrine therapy (ET) for early-stage breast cancer becomes increasingly difficult. Beyond technological breakthroughs and the availability of new classes of drugs, further improvement of adjuvant ET will require applying a rigorous research approach in poorly investigated areas. We critically discuss some key principles that should inform future research to improve ET efficacy, including identifying specific subgroups of patients who can benefit from escalating or de-escalating approaches, optimizing available and new treatment strategies for different clinical contexts, and dissecting the direct and indirect biological effects of therapeutic interventions. Four main issues regarding adjuvant ET were identified as relevant areas, where a better application of such principles can provide positive results in the near future: (i) tailoring the optimal duration of adjuvant ET, (ii) optimizing ovarian function suppression for premenopausal women, (iii) dissecting the biological effects of estrogen receptor manipulation, and (iv) refining the selection of patients to candidate for treatments escalation.

Predictors of Early Versus Late Recurrence in Invasive Lobular Carcinoma of the Breast: Impact of Local and Systemic Therapy

BACKGROUND

Invasive lobular carcinoma (ILC) of the breast is known for high risk of late recurrence, yet some patients still recur within 5 years of diagnosis. Determining factors associated with early/late recurrence could help tailor treatment and surveillance strategies.

METHODS

Using an institutional database, we evaluated patients with ILC and ≥ 5 years of follow-up or recurrence within 5 years. We used multivariate logistic regression and the Kaplan-Meier method to evaluate which clinicopathologic features and treatment strategies were associated with recurrence < 5 years since diagnosis versus recurrence ≥ 5 years since diagnosis. Additionally, we explored the association between Clinical Treatment Score 5 (CTS5) with early versus late recurrence.

RESULTS

Among 513 cases of stage I-III ILC, there were 75 early and 54 late recurrences during a median follow-up period of 9.4 years. Early recurrence was associated with larger tumors (mean 4.2 cm vs. 2.9 cm, p < 0.0001), higher incidence of > 3 positive nodes (32.4% vs. 9.11%, p > 0.0001), and more aggressive tumor biology (low/negative progesterone receptor expression, higher grade, and higher Ki67). Late recurrence was associated with younger age (mean 55.6 vs. 59.2 years, p = 0.037) and elevated body mass index (BMI > 25 kg/m2 in 60.1.0% vs. 45.4%, p = 0.021). Omission of adjuvant endocrine therapy or radiotherapy after lumpectomy conferred increased risk of early rather than late recurrence.

CONCLUSION

Factors related to tumor aggressiveness and treatment were associated with early recurrence, whereas patient related factors were related to late recurrence. These data may help guide treatment strategies and surveillance approaches for patients with ILC.

Ki-67, 21-Gene Recurrence Score, Endocrine Resistance, and Survival in Patients With Breast Cancer

Importance

Both high 21-gene recurrence score (RS) and high Ki-67 level are poor prognostic factors in patients with estrogen receptor (ER)-positive ERBB2-negative (ER+/ERBB-) breast cancer; however, a discrepancy between the 2 has been noted. Survival differences according to these 2 biomarkers are not well known.

Objective

To assess the associations between RS and Ki-67 expression and between Ki-67 expression and recurrence-free survival in patients with ER+/ERBB- breast cancer with low RS.

Design, Setting, and Participants

This cohort study included women treated for ER+/ERBB2- breast cancer who underwent the 21-gene RS test from March 2010 to December 2020 in 2 hospitals in Korea.

Exposures

Recurrence score and Ki-67 level.

Main Outcomes and Measures

A Cox proportional hazards regression model was used to examine the association of Ki-67 with recurrence-free survival (RFS), while a binary logistic regression model was used to examine the association between Ki-67 and secondary endocrine resistance. High Ki-67 expression was defined as 20% or greater, and low genomic risk as an RS of 25 or less. Secondary endocrine resistance was defined as breast cancer recurrence that occurred after at least 2 years of endocrine therapy and during or within the first year after completing 5 years of adjuvant endocrine therapy.

Results

A total of 2295 female patients were included (mean [SD] age, 49.8 [9.3] years), of whom 1948 (84.9%) were in the low genomic risk group and 1425 (62.1%) had low Ki-67 level. The median follow-up period was 40 months (range, 0-140 months). The RS and Ki-67 level had a moderate correlation (R = 0.455; P < .001). Of the patients with low Ki-67 level, 1341 (94.1%) had low RS, whereas 607 of 870 patients with high Ki-67 level (69.8%) had low RS. In patients with low RS, the RFS differed significantly according to Ki-67 level (low Ki-67, 98.5% vs high Ki-67, 96.5%; P = .002). Among the 1807 patients with low genomic risk who did not receive chemotherapy, high Ki-67 level was independently associated with recurrence (hazard ratio, 2.51; 95% CI, 1.27-4.96; P = .008). Recurrence after 3 years differed significantly according to Ki-67 level (low Ki-67, 98.7% vs high Ki-67, 95.7%; P = .003), whereas recurrence within 3 years did not differ (low Ki-67, 99.3% vs high Ki-67, 99.3%; P = .90). In addition, Ki-67 was associated with secondary endocrine resistance in patients with low RS who did not receive chemotherapy (odds ratio, 2.49; 95% CI, 1.13-5.50; P = .02).

Conclusions and Relevance

In this cohort study of patients with ER+/ERBB2- breast cancer, a moderate correlation was observed between Ki-67 and RS, and high Ki-67 level in patients with low genomic risk was associated with increased risk of secondary endocrine resistance.

Special Histologic Type and Rare Breast Tumors - Diagnostic Review and Clinico-Pathological Implications

Breast cancer is the most common malignant tumor in females. While most carcinomas are categorized as invasive carcinoma, no special type (NST), a diverse group of tumors with distinct pathologic and clinical features is also recognized, ranging in incidence from relatively more common to rare. So-called "special histologic type" tumors display more than 90% of a specific, distinctive histologic pattern, while a spectrum of tumors more often encountered in the salivary gland may also arise in the breast. Metaplastic carcinomas can present diagnostic challenges. Some uncommon tumors harbor pathognomonic genetic alterations. This article provides an overview of the key diagnostic points and differential diagnoses for this group of disparate lesions, as well as the salient clinical characteristics of each entity.

ERBB2 mutation is associated with sustained tumor cell proliferation after short-term preoperative endocrine therapy in early lobular breast cancer

Invasive lobular breast cancer (ILC) is a special breast cancer (BC) subtype and is mostly hormone receptor (HR)-positive and ERBB2 non-amplified. Endocrine therapy restrains tumor proliferation and is the mainstay of lobular BC treatment. Mutation of ERBB2 has been associated with recurrent ILC. However, it is unknown whether ERBB2 mutation impacts on the otherwise exquisite responsiveness of early ILC to endocrine therapy. We have recently profiled n = 622 HR-positive early BCs from the ADAPT trial for mutations in candidate genes involved in endocrine resistance, including ERBB2. All patients were treated with short-term preoperative endocrine therapy (pET, tamoxifen or aromatase inhibitors) before tumor resection. Tumor proliferation after endocrine therapy (post-pET Ki67 index) was determined prospectively by standardized central pathology assessment supported by computer-assisted image analysis. Sustained or suppressed proliferation were defined as post-pET Ki67 ≥10% or <10%. Here, we report a subgroup analysis pertaining to ILCs in this cohort. ILCs accounted for 179/622 (28.8%) cases. ILCs were enriched in mutations in CDH1 (124/179, 69.3%, P < 0.0001) and ERBB2 (14/179, 7.8%, P < 0.0001), but showed fewer mutations in TP53 (7/179, 3.9%, P = 0.0048) and GATA3 (11/179, 6.1%, P < 0.0001). Considering all BCs irrespective of subtypes, ERBB2 mutation was not associated with proliferation. In ILCs, however, ERBB2 mutations were 3.5-fold more common in cases with sustained post-pET proliferation compared to cases with suppressed post-pET proliferation (10/75, 13.3% versus 4/104, 3.8%, P = 0.0248). Moreover, ERBB2 mutation was associated with high Oncotype DX recurrence scores (P = 0.0087). In summary, our findings support that ERBB2 mutation influences endocrine responsiveness in early lobular BC.

Prognostic Utility of Breast Cancer Index to Stratify Distant Recurrence Risk in Invasive Lobular Carcinoma

PURPOSE

The prognostic utility of Breast Cancer Index (BCI) for risk assessment of overall (0-10 years), early (0-5 years), and late (5-10 years) distant recurrence (DR) in hormone receptor-positive (HR+) invasive lobular carcinoma (ILC) was evaluated.

EXPERIMENTAL DESIGN

BCI gene expression analysis was performed blinded to clinical outcome utilizing tumor specimens from patients with HR+ ILC from a multi-institutional cohort. The primary endpoint was time to DR. Kaplan-Meier analyses of overall, early, and late DR risk were performed, and statistical significance was evaluated by log-rank test and Cox proportional hazards regression. The prognostic contribution of BCI in addition to clinicopathologic factors was evaluated by likelihood ratio analysis.

RESULTS

Analysis of 307 patients (99% ER+, 53% T1, 42% N+, 70% grade II) showed significant differences in DR over 10 years based on BCI risk categories. BCI low- and intermediate-risk patients demonstrated similar DR rates of 7.6% and 8.0%, respectively, compared with 27.0% for BCI high-risk patients. BCI was a significant independent prognostic factor for overall 10-year DR [HR = 4.09; 95% confidence interval (CI), 2.00-8.34; P = 0.0001] as well as for both early (HR = 8.19; 95% CI, 1.85-36.30; P = 0.0042) and late (HR = 3.04; 95% CI, 1.32-7.00; P = 0.0224) DR. In multivariate analysis, BCI remained the only statistically significant prognostic factor for DR (HR = 3.49; 95% CI, 1.28-9.54; P = 0.0150).

CONCLUSIONS

BCI is an independent prognostic factor for ILC and significantly stratified patients for cumulative risk of 10-year, early, and late DR. BCI added prognostic value beyond clinicopathologic characteristics in this distinct subtype of breast cancer.

Lobular Breast Cancer: Histomorphology and Different Concepts of a Special Spectrum of Tumors

Simple Summary

Invasive lobular breast cancer (ILC) is a special type of breast cancer (BC) that was first described in 1941. The diagnosis of ILC is made by microscopy of tumor specimens, which reveals a distinct morphology. This review recapitulates the developments in the microscopic assessment of ILC from 1941 until today. We discuss different concepts of ILC, provide an overview on ILC variants, and highlight advances which have contributed to a better understanding of ILC as a special histologic spectrum of tumors.

Abstract

Invasive lobular breast cancer (ILC) is the most common special histological type of breast cancer (BC). This review recapitulates developments in the histomorphologic assessment of ILC from its beginnings with the seminal work of Foote and Stewart, which was published in 1941, until today. We discuss different concepts of ILC and their implications. These concepts include (i) BC arising from mammary lobules, (ii) BC growing in dissociated cells and single files, and (iii) BC defined as a morpho-molecular spectrum of tumors with distinct histological and molecular characteristics related to impaired cell adhesion. This review also provides a comprehensive overview of ILC variants, their histomorphology, and differential diagnosis. Furthermore, this review highlights recent advances which have contributed to a better understanding of the histomorphology of ILC, such as the role of the basal lamina component laminin, the molecular specificities of triple-negative ILC, and E-cadherin to P-cadherin expression switching as the molecular determinant of tubular elements in CDH1-deficient ILC. Last but not least, we provide a detailed account of the tumor microenvironment in ILC, including tumor infiltrating lymphocyte (TIL) levels, which are comparatively low in ILC compared to other BCs, but correlate with clinical outcome. The distinct histomorphology of ILC clearly reflects a special tumor biology. In the clinic, special treatment strategies have been established for triple-negative, HER2-positive, and ER-positive BC. Treatment specialization for patients diagnosed with ILC is just in its beginnings. Accordingly, ILC deserves greater attention as a special tumor entity in BC diagnostics, patient care, and cancer research.

Development of a Prognostic Tool to Guide the Decision to Extend Adjuvant Aromatase Inhibitors for up to Ten Years in Postmenopausal Early Breast Cancer Patients

Background: The selection of women with hormone receptor-positive (HR+) early breast cancer (EBC) at high risk of relapse after five years (yrs.) of adjuvant aromatase inhibitors (AIs) is crucial, as the benefit of extending AIs is counterbalanced by toxicity. We developed a clinicopathological tool to estimate the residual risk of relapse after five years of adjuvant AIs. Methods: The Institut de Cancérologie de l'Ouest (ICO) database was used to determine a prognostic score of post-five-year AI relapse. Cox regression models estimated our score's prognostic performance. Results: In total, 1105 women were included. Median follow-up was 44 months (IQR = 21-70) post-AI treatment. From the Cox models, we designed a dichotomous prognostic score including the number of macrometastases, age (>70 yrs. vs. ≤70 yrs.), tumor size (≥T2 vs. not), and mitotic activity (≥2 vs. not). Overall, 77.5% of patients were classified as being at low risk and 22.5% at high risk of late recurrence. Low-risk patients had a five- to ten-year local or distant recurrence risk of 7.6% (95% CI, 5.4% to 10.6%) as compared with 26.9% (95% CI, 19.9% to 35.7%) for the high-risk roup. Conclusion: In this study, we developed a simple tool to identify women at high risk of relapse despite completing five years of AIs.

Validation of Clinical Treatment Score post-5 years (CTS5) risk stratification in premenopausal breast cancer patients and Ki-67 labelling index

This study aimed to validate the Clinical Treatment Score post-5 years (CTS5)-based risk stratification in a cohort comprising pre- and postmenopausal patients with estrogen receptor (ER)–positive breast cancer. We investigated the clinicopathologic parameters including Ki-67 labelling index (LI) to identify factors affecting late distant recurrence (DR). Women with ER-positive breast cancer who were free of DR for 5 years were identified between January 2004 and December 2009. We investigated the risk of late DR (5–10 years) according to the CTS5 risk group. Cox regression analysis was used to determine the prognostic performance of CTS5 and identify factors associated with late DR. In all, 680 women were included. Of these, 379 (55.7%) were premenopausal and 301 (44.3%) were postmenopausal. At a median follow-up of 118 months, 32 women had late DR. CTS5 was a significant prognostic factor for late DR in both pre- and postmenopausal women. In the low CTS5 group, high Ki-67 LI (> 20%) was a significant risk factor for late DR. CTS5 is a useful tool for assessing the risk of late DR in pre- and postmenopausal women with ER-positive breast cancer. Extended endocrine therapy can be considered in patients with high Ki-67 LI (> 20%) in the low CTS5 group.

Correct Identification of Cell of Origin May Explain Many Aspects of Cancer: The Role of Neuroendocrine Cells as Exemplified from the Stomach

Cancers are believed to originate from stem cells. Previously, the hypothesis was that tumors developed due to dedifferentiation of mature cells. We studied the regulation of gastric acid secretion and showed that gastrin through the gastrin receptor stimulates enterochromaffin-like (ECL) cell histamine release and proliferation. In animal and human studies, we and others showed that long-term hypergastrinemia results in ECL cell-derived tumor through a sequence of hyperplasia, dysplasia, neuroendocrine tumors (NETs), and possibly neuroendocrine carcinomas (NECs) and adenocarcinomas of diffuse type. Perhaps, other cancers may also have their origin in differentiated cells. Knowledge of the growth regulation of the cell of origin is important in cancer prophylaxis and treatment. Physiology plays a central role in carcinogenesis through hormones and other growth factors. Every cell division implies a small risk of mutation; thus mitogens are also mutagens. Moreover, metastasis of slow proliferating cells may also explain so-called tumor dormancy and late recurrence.