The role of computed tomography in the selection of breast cancer treatment

Excluding Lung Tissue from the PTV during Internal Mammary Irradiation. A Safe Technique for OAR-Sparing?

Simple Summary

The planning treatment volume (PTV) during internal mammary irradiation (IMNI) regularly overlaps with lung tissue and is often in close proximity to the heart. Thus, exclusion of lung tissue from the PTV is a potential technique to spare the organs at risk (OARs) during adjuvant breast cancer irradiation. Using an innovative dose recalculation and accumulation algorithm, we evaluated the safety of exclusion of lung tissue from the PTV. According to our data, exclusion of lung tissue from the PTV to spare the OARs leads to significant dose reduction in the target volume and can, therefore, not be recommended.

Abstract

The current study aims to determine whether exclusion of lung tissue from planning treatment volume (PTV) is a valid organ at risk (OAR)-sparing technique during internal mammary irradiation (IMNI). Twenty patients with left-sided breast cancer undergoing adjuvant radiotherapy including IMNI after mastectomy or lumpectomy with daily ConeBeam CT (CBCT; median n = 28) were enrolled in the current study. The daily dose distribution of the patients was estimated by recalculating treatment plans on CBCT-scans based on a standard PTV (PTV margin: 5mm-STD) and a modified PTV, which excluded overlapping lung tissue (ExLung). Using 3D-deformable dose accumulation, the dose coverage in the target volume was estimated in dependence of the PTV-margins. The estimated delivered dose in the IMN-CTV was significantly lower for the ExLung PTV compared to the STD PTV: ExLung: V95%: 76.6 ± 22.9%; V90%: 89.6 ± 13.2%, STD: V95%: 95.6 ± 7.4%; V90%: 99.1 ± 2.7%. Daily CBCT imaging cannot sufficiently compensate the anatomic changes and intrafraction movement throughout the treatment. Therefore, to ensure adequate delivery of the prescribed dose to the IMN-CTV, exclusion of lung tissue from the PTV to spare the OARs is not recommended.

Impact of neoadjuvant chemotherapy on locoregional surgical treatment of breast cancer

Preoperative (neoadjuvant) chemotherapy (NC) has become the standard of care for patients with locally advanced breast cancer and is being increasingly used in those with large operable disease. Its main clinical advantages from a surgical therapy standpoint include the potential for conversion of patients requiring mastectomy to breast-conservation candidates, the potential for improving the cosmetic outcome following lumpectomy by decreasing the size of the primary breast tumor even if the patient is a lumpectomy candidate at presentation, and the potential for converting patients who present with positive axillary nodes and who would initially require axillary lymph node dissection to candidates for sentinel lymph node biopsy alone. Important steps are required from the time of diagnosis until the time of surgical resection to ensure successful locoregional therapy outcomes in patients treated with NC. They include accurate assessment of the location and extent of the primary breast tumor and determination of axillary nodal status before and after NC. This information is critical for successful execution of the surgical plan and to optimize the use of adjuvant radiotherapy following NC. In the future, development of more active neoadjuvant chemotherapy regimens and novel molecular and imaging techniques will undoubtedly lead to further individualization of breast cancer surgical management following NC, including the possibility of avoiding surgical resection in cases with a high likelihood of achieving a pathological complete response.

Evaluation of the usefulness of breast CT imaging in delineating tumor extent and guiding surgical management: a prospective multi-institutional study

OBJECTIVE

The aim of the present study was to evaluate the usefulness of computed tomographic (CT) imaging in delineating tumor extent and guiding surgical management.

BACKGROUND

The routine use of preoperative magnetic resonance imaging (MRI) is a controversial issue in breast cancer management. Negative studies with regard to the utility of MRI might be due to differences in positioning during imaging and subsequent surgery.

METHODS

Candidates for breast-conserving surgery were eligible for the study. The surgeons marked the line of planned excision on the skin, which was also recorded on the CT image. Contrast-enhanced breast CT was performed in the supine surgical position. The CT results were used to help determine the extent of resection. The pathological findings were then compared with the CT-guided surgical plans.

RESULTS

A total of 297 patients were involved. The surgeons widened the extent of resection in 42 (14.1%, 95% confidence interval 10.1%-18.1%) patients on the basis of the CT findings. Among the 6 patients whose procedures were changed to mastectomy, 4 had pathologically multicentric tumors and 2 had widely spread intraductal components. The remaining 36 patients underwent quadrantectomy instead of wide excision on the basis of the CT images. There were 3 patients in whom conversion from wide excision to quadrantectomy resulted in overexcision. Preoperative breast CT may have reduced the positive margin rate and also correctly changed the extent of surgery in 13.1% of patients.

CONCLUSIONS

This prospective study suggests that breast CT, carried out in the supine position, is useful in the preoperative determination of the optimal surgical procedure.

Use of contrast-enhanced computed tomography in clinical staging of asymptomatic breast cancer patients to detect asymptomatic distant metastases

The use of computed tomography (CT) with regards to the clinical staging of patients with asymptomatic breast cancer has been on the increase in clinical practice. However, the benefits of routine CT have yet to be fully clarified. This study investigated the value of employing contrast-enhanced CT (CECT) to screen for distant metastases in patients with asymptomatic breast cancer. The clinical records of 483 patients with asymptomatic breast cancer who underwent CECT at a single institution between April 2006 and January 2011 were reviewed retrospectively. The CECT results were classified into normal, true-positive (metastases) or false-positive findings. Abnormal CECT findings, including true- and false-positive results, were detected in 65 patients (13.5%). Of these, 26 patients (5.4%) showed confirmed true metastatic disease, including 18 lung metastases, 11 liver metastases and 13 bone metastases. Upstaging to stage IV due to the results of the CECT scan occurred in 0 of 155 patients at stage I, 5 of 261 patients (1.9%) at stage II and 21 of 67 patients (31.3%) at stage III. The false-positive rates were 7.7, 9.0 and 8.7% in stages I, II and III, respectively. The size of the lung or liver metastasis was significantly larger than the false-positive lesion. Routine CECT did not appear to be useful for detecting distant metastases in completely asymptomatic patients. Conversely, a small number of patients were upstaged from early to stage IV and a predictive factor beyond T and N stage alone appears to be needed in order to predict which asymptomatic patients have distant metastases.

Preoperative CT evaluation of intraductal spread of breast cancer and surgical treatment

It is always a challenge to accurately determine the appropriate extent of resection in breast-conserving surgery (BCS), in order to reduce the need for re-excision, prevent local recurrence, and optimize cosmetic results. Detecting intraductal spread alone with high sensitivity may not be enough to realize safe BCS. Computed tomography carried out with the patient in the supine position accompanied by adequate marking is effective for preoperative determination of the optimum extent of BCS.

Clinical Significance of Multidetector-Row Computed Tomography in Breast Surgery

Several reports support the association of higher ipsilateral breast tumor recurrence rates with positive or intermediate margins compared with negative pathologic margins. Precise evaluation of tumor extension and adequate surgical margin are important factors affecting tumor recurrence after breast-conserving surgery (BCS). Many studies have reported the utility of magnetic resonance imaging (MRI) for diagnosing the tumor extension of breast cancer, but few have evaluated the utility of multidetector-row computed tomography (MDCT). The results of this study show the clinical significance of MDCT for detecting cancer extension and demonstrate the clinical role of MDCT in BCS. Subjects comprised 136 patients grouped into two categories based on whether or not tumor extension was evaluated with MDCT preoperatively. The positive surgical margin rate and breast conservation rate were analyzed in each group and the clinical role of MDCT in BCS was evaluated. Moreover, evaluation of intraductal extension was done both with MDCT and histologically, and computed tomography (CT)-pathologic correlations were examined retrospectively. Finally, the margin-positive cases were analyzed in relation to their clinical characteristics. Sensitivity, specificity, positive predictive value, and negative predictive value for detection of the intraductal component were 71.8%, 85.7%, 82.1%, and 76.9%, respectively. The positive surgical margin rate and conservation rate are 7.46% and 81.9%, respectively, for those who were diagnosed with MDCT preoperatively; their corresponding rates without MDCT were 16.67% and 67.9%. Most margin-positive patients have remarkable lymphatic space invasion. Positive surgical margins were often recognized toward the nipple. For diagnosing the intraductal extension, MDCT shows sufficient diagnosability. Moreover, MDCT can provide appropriate information for the determination of adequate surgical margins and contribute to increases in breast conservation rates.

Two cases of adenoid cystic carcinoma: preoperative cytological findings were useful in determining treatment strategy

Adenoid cystic carcinoma (ACC) of the breast is a rare variant of breast malignancy and is known to have an excellent prognosis. We report two cases of ACC diagnosed by preoperative fine-needle aspiration cytology (FNAC), which proved to be very useful in determining the appropriate treatment. The patients were a 57-year-old woman (case 1) and a 71-year-old woman (case 2). On physical examinations and imaging studies both tumors were recognized as lobulated tumors that measured 3.0 x 2.3 cm (case 1) and 3.9 x 3.4 cm (case 2) respectively. FNAC materials showed clusters of malignant cells surrounding globules of mucus, therefore, ACC was diagnosed. Considering the characteristics of ACC, breast-conserving surgeries with axillary dissection and adjuvant radiotherapy were performed instead of primary chemotherapy or mastectomy. Histologically, a distinctive biphasic pattern was observed that consisted of true laminae and pseudocystic spaces. Tumor sizes were 4.0 x 3.3 cm (case 1) and 4.6 x 3.8 cm (case 2), respectively, and surgical margins were negative on microscopic examination. Lymph node metastasis was not present in either case. Even though ACC is very rare, preoperative diagnosis can be made based on its characteristic features. Preoperative diagnosis is extremely useful for determining appropriate treatment.

Usefulness of three-dimensional multidetector-row CT images for preoperative evaluation of tumor extension in primary breast cancer patients

PURPOSE

Usefulness of three dimensional (3D) multidetector-row CT (MDCT) images for preoperative evaluation of tumor extension was studied in primary breast cancer patients.

METHODS

3D-MDCT tumor images of 143 tumors in 143 patients with primary breast cancer were created with the volume rendering method. The transverse tumor size (TS) and vertical tumor size (VS) were then measured in an anterior-posterior view of the 3D-MDCT images. The pathological tumor size was determined according to a map of the tumor spread prepared by pathologists using multi-sliced (3-5 mm intervals) surgical specimens and compared with the tumor size on 3D-MDCT images.

RESULTS

First, the optimal method for creating 3D-MDCT tumor images was determined for the first 40 patients (learning set), resulting in a fairly good correlation of tumor size on 3D-MDCT images with pathological tumor size (r = 0.983 for TS and r = 0.958 for VS). We then carried out a validation study on the next 103 patients (validation set). The 3D-MDCT tumor size's strong correlation with the pathological tumor size demonstrated a high rate of accuracy (r = 0.974 for TS and r = 0.977 for VS). Subset analyses according to histological type showed that correlation coefficients were r = 0.979 for TS and r = 0.981 for VS of invasive ductal carcinomas (n = 88), r = 0.948 for TS and r = 0.970 for VS of ductal carcinomas in situ (n = 10), and r = 0.984 for TS and r = 0.976 for VS of invasive lobular carcinomas (n = 5).

CONCLUSION

3D-MDCT images can assess breast cancer tumor extension highly accurately, and thus seems to be useful for planning the extent of resection in breast conserving surgery.

Multidetector row computed tomography for diagnosing intraductal extension of breast carcinoma

OBJECTIVES

Several reports supported the association of higher ipsilateral breast tumor recurrence rates with positive or intermediate margins compared with negative pathologic margins. Precise evaluation of intraductal component and adequate surgical margin are important factors affecting the tumor recurrence after breast conserving surgery. Numerous studies have reported the utility of magnetic resonance imaging for diagnosing developing intraductal extension of breast cancer, but few have investigated multidetector-row computed tomography (MD-CT). The present study evaluated the clinical utility of MD-CT for detecting intraductal extension of breast carcinoma, and analyzed clinical parameters affecting the detection of intraductal extension under MD-CT.

METHODS

Subjects comprised 44 patients grouped into three categories according to degree of intraductal extension of the main tumor under MD-CT (Intraductal spread grade 1 approximately 3: IDS 1 approximately 3). Tumors were also categorized histopathologically (p-IDS 0 approximately 3), and CT-pathological correlations were examined retrospectively. Clinical parameters were evaluated to determine the affect on detection of intraductal components.

RESULTS

MD-CT detected 44 breast lesions (100%). Sensitivity for detection of intraductal component was 81.2%, specificity was 67.8%, and accuracy was 72.7%. Regarding extent of intraductal components, significant correlations were found between histopathological and MD-CT findings. A strong correlation was found in postmenopausal women between T2 tumor and high histological grade.

CONCLUSIONS

MD-CT findings of intraductal extension from breast carcinoma correlate with histological degree of intraductal extension, and MD-CT may be useful for preoperative assessment of breast-conserving surgery, particularly for postmenopausal women with histological high nuclear grade and T2 tumor.