Clinical relevance of the distribution of the lesions in 500 consecutive breast cancer cases documented in large-format histologic sections

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.

A new era in the diagnosis and treatment of breast cancer

Randomized controlled mammography screening trials and the evaluation of service screening have unequivocally proven that regular mammography screening significantly reduces mortality from breast cancer. This evidence contradicts the theory of Fisher, claiming that breast cancer is a systemic disease from its inception and undermines the justification for systemic therapy in most screen-detected cancers, because they are still localized to the breast and can be cured by local treatment alone. When high quality mammographic screening is offered at regular intervals to 40- to 74- year-old women, over 50% of the invasive cancers will be detected in the size range of 1-14 mm, fewer than 20% will be axillary node positive, and only about 20% will be poorly differentiated. This predominance of early-stage disease has created a revolutionary new era for those involved in the diagnosis and treatment of patients with breast cancer.

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.

Precise correlation between MRI and histopathology - exploring treatment margins for MRI-guided localized breast cancer therapy

BACKGROUND

Magnetic resonance imaging (MRI) is more often considered to guide, evaluate or select patients for partial breast irradiation (PBI) or minimally invasive therapy. Safe treatment margins around the MRI-visible lesion (MRI-GTV) are needed to account for surrounding subclinical occult disease.

PURPOSE

To precisely compare MRI findings with histopathology, and to obtain detailed knowledge about type, rate, quantity and distance of occult disease around the MRI-GTV.

METHODS AND MATERIALS

Patients undergoing MRI and breast-conserving therapy were prospectively included. The wide local excision specimens were subjected to detailed microscopic examination. The size of the invasive (index) tumor was compared with the MRI-GTV. The gross tumor volume (GTV) was defined as the pre-treatment visible lesion. Subclinical tumor foci were reconstructed at various distances to the MRI-GTV.

RESULTS

Sixty-two patients (64 breasts) were included. The mean size difference between MRI-GTV and the index tumor was 1.3mm. Subclinical disease occurred in 52% and 25% of the specimens at distances ≥10mm and ≥20mm, respectively, from the MRI-GTV.

CONCLUSIONS

For MRI-guided minimally invasive therapy, typical treatment margins of 10mm around the MRI-GTV may include occult disease in 52% of patients. When surgery achieves a 10mm tumor-free margin around the MRI-GTV, radiotherapy to the tumor bed may require clinical target volume margins >10mm in up to one-fourth of the patients.

Immediate reconstruction following breast-conserving surgery: management of the positive surgical margins and influence on secondary reconstruction

The efficacy of breast-conserving surgery for the local control of early breast cancer has been repeatedly evidenced. Although immediate reconstruction following breast-conserving surgery has been described, little information is available regarding surgical management in reoperative settings due to positive margins. We studied the influence of intraoperatively assessed and postoperatively controlled surgical margin status on the type of breast-conserving surgery and report our results regarding complications in a reoperative breast reconstruction scenario. All patients were seen by a multidisciplinary team who recommended breast-conserving surgery. According to the breast volume, ptosis and tumor size/location, the patients were also evaluated by a plastic surgeon, who recommended reconstruction with the appropriate technique. Intraoperative assessment of surgical margins was determined by histological examination of frozen sections. The mean follow-up time was 48 months. Two hundred and eighteen patients (88.5%) underwent breast-conserving surgery and immediate reconstruction. Twelve (5.5%) patients had a positive tumor margin after review of the permanent section. All patients underwent re-exploration. In 1.3%, a second reconstructive technique was indicated and in 2.2% a skin-sparing mastectomy with total reconstruction was performed. Our findings support the important role of the intraoperative assessment of surgical margins and its interference in the selection of reconstruction techniques and negative margins; however, it will not guarantee complete excision of the tumor. Success depends on coordinated planning with the oncologic surgeon and careful intraoperative management.