The distribution of lesions in 1–14-mm invasive breast carcinomas and its relation to metastatic potential

Mass and non-mass breast MRI patterns: a radiologic approach to sick lobe theory

BACKGROUND

According to sick lobe theory, one or more lobes of the breast are more prone to the development of carcinoma. However, the implications of this theory in breast magnetic resonance imaging (MRI) are unknown.

PURPOSE

To evaluate the MRI appearance of mass type (multifocal and multicentric diseases) and non-mass type (non-mass enhancements) sick lobe patterns, together with the histopathology results.

MATERIAL AND METHODS

MRI reports of 2015 patients in two tertiary breast imaging centers between June 2012 and June 2018 were retrospectively reviewed for multifocal-multicentric diseases and segmental, linear, and regional enhancements. A total of 113 patients were included. The specimens obtained by thick needle, vacuum, excisional biopsy/lumpectomy or mastectomy after breast MRI scans were pathologically assessed. The pathologic results were categorized as invasive carcinoma, precursor, and benign proliferative lesions according to the 2012 World Health Organization Classification of Tumors.

RESULTS

The percentage of underlying benign and precursor invasive lesions was significantly different in patients with mass and non-mass MRI patterns. While the pathology results of mass type patterns were premalignant and malignant in all cases, nearly half of the underlying histologies were benign proliferative subtypes in patients with non-mass type patterns.

CONCLUSION

In this study, the mass and non-mass patterns derived from sick lobe theory were related to different risks of malignancy in the pathological examinations.

Histo-genomics: digital pathology at the forefront of precision medicine

The toughest challenge OMICs face is that they provide extremely high molecular resolution but poor spatial information. Understanding the cellular/histological context of the overwhelming genetic data is critical for a full understanding of the clinical behavior of a malignant tumor. Digital pathology can add an extra layer of information to help visualize in a spatial and microenvironmental context the molecular information of cancer. Thus, histo-genomics provide a unique chance for data integration. In the era of a precision medicine, a four-dimensional (4D) (temporal/spatial) analysis of cancer aided by digital pathology can be a critical step to understand the evolution/progression of different cancers and consequently tailor individual treatment plans. For instance, the integration of molecular biomarkers expression into a three-dimensional (3D) image of a digitally scanned tumor can offer a better understanding of its subtype, behavior, host immune response and prognosis. Using advanced digital image analysis, a larger spectrum of parameters can be analyzed as potential predictors of clinical behavior. Correlation between morphological features and host immune response can be also performed with therapeutic implications. Radio-histomics, or the interface of radiological images and histology is another emerging exciting field which encompasses the integration of radiological imaging with digital pathological images, genomics, and clinical data to portray a more holistic approach to understating and treating disease. These advances in digital slide scanning are not without technical challenges, which will be addressed carefully in this review with quick peek at its future.

Application of a novel prognostic invasive lesion index in ductal carcinoma in situ with minimal invasion of the breast

Multiple invasive foci has been shown to increase the risk of lymph node metastasis (LNM) in early breast cancer, but its prognostic implication remains unknown. We aimed to identify the prognostic value of the number of invasive foci in ductal carcinoma in situ with minimal invasion of the breast (DCIS‐MI), and further establish a prognostic invasive lesion index (ILI). A total of 193 patients with DCIS‐MI (the invasive component was up to 10 mm in diameter) were included. Univariate and multivariate analysis (logistic regression) were used to evaluate the predictive value of the number of invasive foci in LNM. The Kaplan–Meier curve was used for survival analysis. More than five invasive foci was an independent predictor for LNM (OR, 2.67, 95% CI, 1.12–6.33, P = 0.026), and associated with significantly shorter disease‐free survival (DFS) and overall survival (OS) compared with no more than five invasive foci (mean DFS 123.8 vs. 148.0 months, P = 0.002; and mean OS 133.5 vs. 151.4 months, P = 0.025). The ILI was established by the sum scores of the number of invasive foci and the invasive component size, having an optimal cut‐off point of 5.5 scores. The high‐ILI group (ILI >5 scores) had a higher incidence of LNM (23.6% vs. 6.9%) and worse prognosis than the low‐ILI group (ILI ≤5 scores). In conclusion, more than five invasive foci was an independent predictor for LNM and an unfavorable prognostic parameter. The ILI could potentially be used to predict survival prognosis in patients with DCIS‐MI.

3D Pathology Volumetric Technique: A Method for Calculating Breast Tumour Volume from Whole-Mount Serial Section Images

Tumour size, most commonly measured by maximum linear extent, remains a strong predictor of survival in breast cancer. Tumour volume, proportional to the number of tumour cells, may be a more accurate surrogate for size. We describe a novel “3D pathology volumetric technique” for lumpectomies and compare it with 2D measurements. Volume renderings and total tumour volume are computed from digitized whole-mount serial sections using custom software tools. Results are presented for two lumpectomy specimens selected for tumour features which may challenge accurate measurement of tumour burden with conventional, sampling-based pathology: (1) an infiltrative pattern admixed with normal breast elements; (2) a localized invasive mass separated from the in situ component by benign tissue. Spatial relationships between key features (tumour foci, close or involved margins) are clearly visualized in volume renderings. Invasive tumour burden can be underestimated using conventional pathology, compared to the volumetric technique (infiltrative pattern: 30% underestimation; localized mass: 3% underestimation for invasive tumour, 44% for in situ component). Tumour volume approximated from 2D measurements (i.e., maximum linear extent), assuming elliptical geometry, was seen to overestimate volume compared to the 3D volumetric calculation (by a factor of 7x for the infiltrative pattern; 1.5x for the localized invasive mass).

The role of large-format histopathology in assessing subgross morphological prognostic parameters: a single institution report of 1000 consecutive breast cancer cases

Breast cancer subgross morphological parameters (disease extent, lesion distribution, and tumor size) provide significant prognostic information and guide therapeutic decisions. Modern multimodality radiological imaging can determine these parameters with increasing accuracy in most patients. Large-format histopathology preserves the spatial relationship of the tumor components and their relationship to the resection margins and has clear advantages over traditional routine pathology techniques. We report a series of 1000 consecutive breast cancer cases worked up with large-format histology with detailed radiological-pathological correlation. We confirmed that breast carcinomas often exhibit complex subgross morphology in both early and advanced stages. Half of the cases were extensive tumors and occupied a tissue space ≥40 mm in its largest dimension. Because both in situ and invasive tumor components may exhibit unifocal, multifocal, and diffuse lesion distribution, 17 different breast cancer growth patterns can be observed. Combining in situ and invasive tumor components, most cases fall into three aggregate growth patterns: unifocal (36%), multifocal (35%), and diffuse (28%). Large-format histology categories of tumor size and disease extent were concordant with radiological measurements in approximately 80% of the cases. Noncalcified, low-grade in situ foci, and invasive tumor foci <5 mm were the most frequent causes of discrepant findings.

Axillary lymph node status in unifocal, multifocal, and diffuse breast carcinomas: differences are related to macrometastatic disease

BACKGROUND

Multifocality in breast carcinoma is associated with an increased propensity to metastasis. However, it is not clear whether this propensity manifests in the form of macrometastases or as presumably less-significant low-volume metastatic disease.

METHODS

A total of 948 cases of invasive breast carcinoma documented in large-format histology sections and assessed with detailed radiologic-pathologic correlation were categorized as unifocal, multifocal, or diffuse on the basis of the subgross distribution of the invasive component. Rates of macrometastases (>2 mm), micrometastases (0.2-2 mm), and isolated tumor cells (<0.2 mm) in these categories were compared. The influence of tumor size and histology grade on lymph node positivity rates was also tested.

RESULTS

Macrometastases were present in 20.4% (112 of 550) of unifocal, 48.3% (172 of 356) of multifocal, and 61.9% (26 of 42) of diffuse cases (P < 0.0001). Among the macrometastatic cases, more than three nodes were involved in 18.9% (21 of 112) of unifocal, 35.5% (61 of 172) of multifocal, and 50.0% (13 of 26) of diffuse cases. The rates of micrometastases (5.1, 5.1, and 2.4% unifocal, multifocal, and diffuse, respectively) and isolated tumor cells (4.5, 3.7, and 2.4% unifocal, multifocal, and diffuse, respectively) were low and similar in all examined categories. The relative risk (RR) of having macrometastatic disease was approximately doubled (RR 2.3726, P < 0.0001) in multifocal and tripled (RR 3.0562, P < 0.0001) in diffuse compared to unifocal cases. The findings were similar for all size categories, tumor grade categories, and sentinel lymph nodes, as well as all examined lymph nodes.

CONCLUSIONS

The significantly increased lymph node positivity rates in multifocal and diffuse invasive breast carcinomas results from large-volume macrometastatic disease.

Disease Extent ≥4 cm Is a Prognostic Marker of Local Recurrence in T1-2 Breast Cancer

Despite improvements of the therapy for breast cancer, a proportion of the patients still get local recurrence. The status of the surgical margins is the most often used parameter for decision regarding additional treatment. However, a negative margin is not a guarantee that there is not residual cancer left in the breast; additional parameters are needed to better predict the risk of local recurrence. The disease extent was evaluated in the surgical specimen from 313 women after breast-conserving therapy using large-section histology and was correlated to the incidence of local recurrence. A disease extent ≥4 cm was shown to be an independent marker for local recurrence; the cumulative 10-year local relapse rate for the group with a disease extent ≥4 cm was 20.5%, and for the rest 6.7%. We conclude that disease extent ≥4 cm seems to be an important factor when evaluating the risk for local recurrence.

Redefining lumpectomy using a modification of the "sick lobe" hypothesis and ductal anatomy

Objectives. The “Sick Lobe” hypothesis states that breast cancers evolve from entire lobes or portions of lobes of the breast where initiation events have occurred early in development. The implication is that some cancers are isolated events and others are truly multi-focal but limited to single lobar-ductal units. Methods. This is a single surgeon retrospective review of early stage breast cancer lumpectomy patients treated from 1/2000 to 2/2005. Ductal endoscopy was used direct lumpectomy surgical margins by defining ductal anatomy and mapping proliferative changes within the sick lobe for complete excision. Results. Breast conservation surgery for stage 0–2 breast cancer with an attempt to perform endoscopy in association with therapeutic lumpectomy was performed in 554 patients (successful endoscopy in 465 cases). With an average followup of >5 years for the entire group, annual hazard rate for local failure in traditional lumpectomy without ductal mapping was 0.97%/yr. and for lumpectomy with ductal mapping and excision of entire sick lobe was 0.18%/yr. With endoscopy, 42% of patients were found to have extensive disease within their “sick lobe.” Conclusions. Targeting breast cancer lumpectomy using endoscopy and excision of regional associated proliferation seems associated with lower recurrence in this non-randomized series.

Breast cancer multifocality, disease extent, and survival

The prognostic information implied in subgross morphologic parameters such as lesion distribution (unifocal, multifocal, or diffuse) and disease extent in breast cancer has remained largely unexplored in the literature. We aimed to test whether these parameters influence survival in breast carcinoma. The parameters were assessed in a series of 574 cases, all documented in large-format histology sections. We used Cox proportional hazards regression accompanied by Kaplan-Meyer survival curves, with P < .05 regarded as significant. The invasive component was unifocal in 62% (311/499), multifocal in 24% (122/499), and diffuse in 5% (26/499) of the cases. Combining the in situ and invasive tumor components resulted in 48% (274/574) unifocal, 25% (141/574) multifocal, and 20% (117/574) diffuse tumors. Sixty percent (347/574) of the tumors were categorized as having limited extent (occupying an area <40 mm in largest dimension) and 29% (164/574) as extensive. Highly significant (P < .0001) differences were observed in 10-year disease-specific cumulative survival among the cases with unifocal, multifocal, and diffuse invasive (89.6%, 76.0%, and 63.6%, respectively) and combined (92.3%, 82.3%, and 75.7%, respectively) lesion distribution. Patients with extensive tumors exhibited a significantly lower cumulative survival (P < .0001) compared with those with limited extent (91.6% and 75.5%) and a statistically significantly 1.89-fold (95% confidence interval, 1.07-3.37; P = .03) risk for breast cancer death after controlling for tumor attributes, type of surgery, and adjuvant therapy. The hazard ratio for breast cancer death for mutifocal and/or diffuse tumors versus unifocal ones was 1.96 (95%; 1.11-3.48; P = .02) after controlling for the same factors. Lesion distribution and disease extent represent important independent survival-related prognostic parameters in breast carcinoma.

Subgross morphology, the sick lobe hypothesis, and the success of breast conservation

Breast carcinoma has a complex subgross morphology in the majority of cases. The malignant transformation usually involves a single breast lobe and may demonstrate peripheral, segmental, or lobar growth patterns in the in situ phase. During the invasive phase, the tumor may grow beyond the borders of the affected lobe. The dimensions of the involved lobe and the pattern of its involvement determine the extent of the disease in the early phase, with the size, type, and position of the invasive foci being additional determinants in more advanced cases. Breast carcinomas of limited extent (occupying a tissue area <40 mm) are proper candidates for breast-conserving surgery. In other cases, careful individual preoperative assessment of disease extent is necessary in making decisions about the most appropriate surgical approach, taking into account the position of the lesion(s) within the breast, the dimensions of the breast, and patient preference.

Multifocality in "basal-like" breast carcinomas and its influence on lymph node status

BACKGROUND

Basal-like breast carcinomas often are regarded for circumscribed solitary lesions having unfavorable prognosis. On the other hand, a considerable proportion of breast carcinomas is multifocal and has increased metastatic potential. In this study, we analyzed the subgross distribution of the lesions in a series of basal-like carcinomas, compared it with that in nonbasal-like tumors and studied the frequency of vascular invasion and lymph node metastasis in relation to focality of the lesions.

METHODS

A total of 511 consecutive cases documented in large-format histologic sections were studied. Tumors expressing at least one of the basal (myoepithelial) markers (CK5/6, CK14, EGFR) in at least one of the invasive tumor foci were categorized as basal-like tumors. Triple-negative (ER/PR/HER-2-negative) basal-like carcinomas also were analyzed. The distribution of lesions and the frequency of vascular invasion and lymph node metastasis were analyzed. The study was approved by the Regional Ethical Committee Uppsala-Örebro.

RESULTS

In 44% of cases, the invasive component was multifocal or diffuse. Combining the in situ and invasive tumor components resulted in 61% of cases with multifocal/diffuse distribution. The only statistically significant difference observed was that basal-like tumors lacked in situ components more often (21% vs. 9%; P = 0.0075). No significant differences could be demonstrated regarding vascular invasion and lymph node status. Lymph node metastasis appeared significantly more frequently in multifocal cases in both tumor categories.

CONCLUSIONS

Basal-like breast carcinomas are as frequently multifocal as their non-basal-like counterparts; multifocality is associated with increased risk for vascular invasion and lymph node metastasis in both tumor categories.

Molecular phenotypes of unifocal, multifocal, and diffuse invasive breast carcinomas

We analyzed the subgross distribution of the invasive component in 875 consecutive cases of breast carcinomas using large-format histology sections and compared the immunophenotype (estrogen and progesterone receptor expression, HER2 overexpression and expression of basal-like markers, CK5/6, CK14, and epidermal growth factor receptor) in unifocal, multifocal, and diffuse tumors. Histology grade and lymph node status were also analyzed. Unifocal invasive carcinomas comprised 58.6% (513/875), multifocal invasive carcinomas 36.5% (319/875), and diffuse invasive carcinomas 4.9% (43/875) of the cases. The proportion of lymph node-positive cases was significantly higher in multifocal and diffuse carcinomas compared to unifocal cancers, but no other statistically significant differences could be verified between these tumor categories. Histological multifocality and diffuse distribution of the invasive tumor component seem to be negative morphologic prognostic parameters in breast carcinomas, independent of the molecular phenotype.

The role of radiological-pathological correlation in diagnosing early breast cancer: the pathologist's perspective

Early breast carcinoma, defined as purely in situ cancer and invasive carcinomas < 15 mm, represents the most frequent category of breast carcinomas in diagnostic routine in a regularly screened population. These tumors are usually detected with mammography screening and are preoperatively characterized with radiological imaging. The role of pathology in preoperative settings is to help understand the subgross morphology and to confirm malignancy in biopsy material. Postoperatively, the pathologist needs to verify the size of the cancer (defined as the largest dimension of the largest invasive focus), the extent of the disease (defined as the area or the volume of the breast tissue containing all the malignant foci), the distribution of the in situ and invasive lesions (as unifocal, multifocal, or diffuse), and intratumoral and intertumoral heterogeneity (in addition to determining margin status, histologic tumor type, hormone receptor status, and other parameters). Despite their small size, early breast carcinomas often exhibit complex morphology as they are multifocal/diffuse in about 60% and extensive (occupying an area ≥ 4 cm) in 40% of the cases. Routine use of large-format histopathology technique is a prerequisite for detailed correlation of the radiologic and histopathologic findings and for the correct assessment of these parameters. Breast pathologists must be aware of the advantages and disadvantages of the different imaging modalities and have detailed information about the radiological findings before work-up of the operative specimen. Multidisciplinary preoperative and postoperative tumor board meetings are essential in guiding the pathologists and in confirming the radiological findings. Interdisciplinary diagnosis is inevitably becoming the new gold standard in the diagnosis and management of early breast carcinomas.