[Effects of Olaparib, a PARP-1 Inhibitor, on Triple Negative Breast Cancer Cells with a BRCA1 Mutation].

In 2018, olaparib, a PARP inhibitor, was approved for the treatment of BRCA1/2 gene-mutation positive and HER2-negative inoperable and recurrent breast cancer; BRCA1/2 gene testing was also listed as a companion diagnostics. Here, we identified microRNAs(miRNAs) expressed after treatment with olaparib, which differed in the presence or absence of BRCA1 mutations in triple negative breast cancer(TNBC), and examined the changes in miRNAs after exposure to the combination of the PARP-1 inhibitor and a chemotherapeutic agent. After exposure to the PARP-1 inhibitor, the expression of miR-141, miR-155, miR-205, and miR-223 decreased in MDA-MB-231, HCC1143, and BT549 cells and increased more than 10 times in MDA-MB-436 cells. Moreover, the expression of miR-141 in MDA-MB-436 cells treated with the PARP-1 inhibitor together with gemcitabine increased more than 10 times; additionally, the expression of miR-205 increased more in the context of combination therapy versus single exposure to olaparib. The miR-200 family(including miR-141)and miR- 205 are known to function as ZEB1/2 targets and to act as epithelial-to-mesenchymal transition(EMT)-suppressors. Overall, these results suggest that it may be possible to recover the sensitivity of TNBC cells to chemotherapy via the suppressing EMT through the use of a PARP-1 inhibitor in the context of BRCA1 mutation.

Skin grafting utilizing a skin of lateral thoracic area for chest wall reconstruction in patient who underwent mastectomy for locally advanced breast cancer.

Locally advanced breast cancer sometimes results in a large chest wall defect at mastectomy. When closing the wound horizontally, the skin tension is usually severe in the middle of the wound, while the skin of the lateral area tends to make a dog-ear deformity. Triangle technique is a procedure to prevent the dog ear in which the skin and subcutaneous fat of the axilla are cut into an equilateral triangle. Herein, we present a case of breast cancer who underwent a mastectomy and closed the wound with a skin graft by utilizing the skin removed from lateral thoracic area using triangle technique. An 85-year-old female visited our institution complaining about the mass on her right breast. Preoperative images showed a 10 cm-sized mass with suspicious axillary and mediastinal lymph nodes swelling. A biopsy revealed a hormone receptor-negative, HER2-positive invasive ductal carcinoma. A mastectomy and axillary lymph node sampling were performed for a local control as the tumor did not respond to four cycles of triweekly trastuzumab combined with S-1. After a transverse elliptical incision, a skin of the lateral thoracic area was harvested using triangle technique. As the middle of the wound had excessive closing tension, the skin was grafted on the defect. After 10 day fixation by a tie-over dressing, the wound healed without complications. This procedure is a simple method for closing a large defect after mastectomy preventing both the dog-ear deformity and a new wound scarring of a donor site.

Protein expression profile and microRNA expression signature in estrogen receptor-positive and -negative breast cancers: report of two cases.

BACKGROUND: Identification of the proteins that are associated with estrogen receptor (ER) status is a first step in selecting drugs against hormone-dependent breast cancer. Recently, the proteins associated with ER status were reported using liquid chromatography and tandem mass spectrometry, and microRNA (miRNA) profiling of breast cancer subtype was demonstrated using real-time-PCR. METHODS: We present herein two cases with differential protein expression and miRNA profiling in ER-positive and -negative breast cancer. RESULTS: Proteins associated with fatty acid metabolism were uniquely detected in ER-positive breast cancer. The level of miR-181a expression in ER-positive cancer was higher than that in ER-negative cancer, while the expression of miR-27a, miR-107, and miR-195 was lower in ER-positive compared with ER-negative cancer. CONCLUSION: These cases suggest that fatty acid synthase (FAS) and FAS-related miRNAs are important in ER-positive breast cancer.

Evaluation of the dislocation and long-term sonographic detectability of a hydrogel-based breast biopsy site marker.

PURPOSE: To evaluate the usefulness of the HydroMARK, a hydrogel-based breast biopsy site marker for ultrasound localization of breast lesions, we investigated the tendency for dislocation and sonographic detectability of the marker placed in patients. MATERIALS AND METHODS: The marker was placed in lesions that were expected to become obscured after biopsy for a suspicious breast lesion or after neoadjuvant chemotherapy for breast cancer. The patients consented to return for a repeat ultrasound ± mammography examination, and the degree of displacement of the marker was measured as the marker-to-residual lesion distance. RESULTS: The marker was placed after stereotactic biopsy, ultrasound-guided biopsy, and before/during neoadjuvant chemotherapy, in 11, 22, and 7 lesions, respectively. Surgical resection was performed for 22 of the 40 lesions, while remaining 18 benign lesions were followed. The marker was sonographically detectable in 89.7% (35/39), 100% (35/35), and 100% (18/18) of the cases, respectively, at a median of 8 days, 13 weeks, and 11 months after the deployment. The degree of displacement was lower in the ultrasound-guided placement group than in the stereotactic placement group (median displacement: 0 vs. 4.3 mm; p = 0.001), it was also lower in the core-needle biopsy and neoadjuvent therapy cases than in the vacuum-assisted biopsy cases (p = 0.003). At a median interval of 2.5 months after deployment, the marker remained unchanged in location in all cases (n = 18, p = NS). CONCLUSIONS: The HydroMARK appears to be a safe and effective marker with the advantageous characteristics of a low tendency for dislocation with time and long-term sonographic detectability.

Evaluation of the sonographic visibility and sonographic appearance of the breast biopsy marker (UltraClip®) placed in phantoms and patients.

PURPOSE: To evaluate the usefulness of the UltraClip® dual trigger breast tissue marker (UltraClip) for sonographic localization, we investigate the sonographic visibility and sonographic appearance of the UltraClip placed in phantoms and patients. MATERIALS AND METHODS: Ten UltraClips were placed in the target lesions in the phantoms. After the ultrasound examination of the UltraClip, the ultrasound images were compared to the real appearance of the UltraClip obtained by cutting the phantoms. In the patient, the UltraClip markers were placed after biopsy of a suspicious breast lesion or before or during neoadjuvant chemotherapy. The patients consented to return 1-3 weeks after the procedure for ultrasound imaging of the UltraClip. RESULTS: The UltraClip placed in the phantom appeared as a hyperechoic structure with a mean maximum diameter of 5.5 mm, which was found to correspond to the metallic clip in 90% (9/10) of the cases, and as a hyperechoic tubular structure with a maximum diameter of 9.0 mm corresponded to the expanded polyvinyl alcohol polymer in the remaining 10% (1/10) of cases. On the other hand, the UltraClip was detected as a hyperechoic structure measuring 3.5 mm in size only in 9 of the 15 (60%) patients. The sonographic visibility of the UltraClip was not affected depending on whether the target lesion or post-biopsy scar was sonographically detectable or not [60% (6/10) vs. 60% (3/5)]. CONCLUSIONS: While sonographic localization by targeting the UltraClip may be useful in 60% of the patients, another localization technique will be needed in the remaining patients.

Local recurrence following treatment for breast cancer with an endoscopic nipple-sparing mastectomy.

PURPOSE: Endoscopic nipple-sparing mastectomy (E-NSM) has been reportedly associated with smaller scars and greater patient satisfaction; however, long-term results of this procedure have not been made. The purpose of this retrospective study was to investigate the local recurrence (LR) rate and factors associated with it after E-NSM and to examine the oncologic safety of this procedure. METHODS: We reviewed the medical records of a total of 421 breasts in 404 patients who underwent E-NSM to investigate the LR rate and the factors associated with it. The clinico-pathological features and the treatment and outcomes of the patients with LRs were also examined. RESULTS: Eleven breasts (2.6 %) in 11 patients presented with LR as the first site of recurrence after a median follow-up time of 61 months. Among the 11 LRs, 9 patients presented with LR only, 1 patient exhibited regional lymph node recurrence, and 1 patient exhibited distant metastasis. The median time from surgery until LR was 25 months. Eight LRs developed near the original tumor site. The risk factors for LR in a multivariate analysis were a younger age of less than 40 years (p = 0.02), Stage III tumor (p = 0.01), and an inadequate surgical margin (p = 0.001). After the treatment, 6 patients had no evidence of disease, 2 patients died from metastatic disease, 2 patients experienced repeat LR, and the remaining patient who rejected excision exhibited a persistent LR. CONCLUSIONS: E-NSM is an oncologically safe procedure and an acceptable method in selected patients requiring a mastectomy.

Advanced hepatocellular carcinoma responds to MK615, a compound extract from the Japanese apricot "Prunus mume".

MK615, a compound extracted from the Japanese apricot "Prunus mume" has been reported to have in vitro anti-tumor activities against several cancer cell lines, including hepatocellular carcinoma (HCC). However, the clinical effects and feasibility of administering MK615 for patients with HCC were unknown. We experienced a case with advanced HCC for which MK615 was effective against both lymph node and pulmonary metastases. A 60-year-old female underwent surgical resection of a 9 cm HCC in the right lobe. The pathological diagnosis was moderately differentiated HCC with vascular invasion. The HCC recurred in the liver 8 mo after the surgery. Radiofrequency ablation and transarterial infusion chemotherapy were performed, but the recurrence was not controlled. One year after the intrahepatic recurrence, pulmonary and lymph metastasis appeared. Sorafenib was administered, but was not effective. Then, MK615 was administered as a final alternative therapy after informed consent was obtained from the patient. Three months later, her alpha-fetoprotein level decrease and both the lymph node and pulmonary metastases decreased in size. The patient has survived for more than 17 mo after the MK615 administration, and was in good condition. Although further investigations are necessary to clarify its safety and efficacy in humans, MK615 may be useful for the treatment of HCC, without serious adverse effects.

[A case of so-called carcinosarcoma of the middle portion of the bile duct diagnosed preoperatively].

A 73-year-old man was admitted to a hospital with a complaint of epigastralgia and for evaluation of liver dysfunction. After hospitalization, he experienced disturbance of consciousness with septic shock, and was then transferred to our hospital. Computed tomography revealed dilatation of the intrahepatic bile duct and tumor of the middle bile duct. We diagnosed acute obstructive suppurative cholangitis. As a result, endoscopic nasobiliary drainage was performed, and the patient recovered. Based on pathological examinations of the bile duct biopsy specimen, the tumor was diagnosed as a carcinosarcoma. Consequently, the patient underwent pylorus-preserving pancreatoduodenectomy. However, 4 months after surgery, the patient died due to widespread metastasis of the carcinosarcoma. Preoperative diagnosis of carcinosarcoma of the bile duct is extremely rare. Our study suggests the efficacy of bile duct biopsy in such cases.

Is MRI useful for the prediction of nipple involvement?

BACKGROUND: The purpose of this retrospective study was to examine the usefulness of MRI for predicting nipple involvement. METHODS: A retrospective review was performed of 81 breasts in 78 breast cancer patients who had undergone nipple or nipple-areolar complex resections during surgery. The enhancement patterns of the nipple on MRI were compared to the contralateral side and were categorized as no enhancement, bilateral enhancement, and unilateral enhancement. The physical examination results, MRI findings, and pathological findings were assessed. RESULTS: Nipple involvement was observed in 17 of 81 nipples (21%), of which one exhibited infiltration of invasive ductal carcinoma, 12 exhibited ductal carcinoma in situ, and four exhibited Paget's disease. The nipples with no enhancement or with bilateral enhancement on MRI showed a lower rate of nipple involvement than the nipples with unilateral enhancement (0/48 vs. 17/33, p < 0.001). Among the unilaterally enhanced nipples, those with continuous enhancement from the index lesion showed a higher rate of nipple involvement than those without continuous enhancement (16/26 vs. 1/7, p = 0.03). When the enhancement characteristics of the unilaterally enhanced nipples were categorized, the findings with relatively high positive predictive values for nipple involvement were diffuse enhancement (100%, 2/2), unilateral skin enhancement (100%, 2/2), rim enhancement (86%, 6/7), and periductal enhancement (80%, 4/5). CONCLUSIONS: MRI was useful for predicting nipple involvement. Unilateral enhancement of the nipple with continuous enhancement from the index lesion may suggest the possibility of nipple involvement.

Drug induced hypersensitivity syndrome by triple therapy of peginterferon alpha2b, ribavirin and telaprevir in patient with double positive for HBV and HCV.

Sixty year-old male positive for both HCV-RNA and HBsAg was treated by triple therapy of peginterferon alpha2b, ribavirin and telaprevir. Eight weeks after the beginning of the therapy, the patient developed drug induced hypersensitivity syndrome (DIHS) with general erythema multiforme and 64 times anti-HHV6 antibody elevation. Sixty milligram of prednisolone was administered with gradual dose reduction and the skin lesion was improved. HBV-DNA and transaminase elevated one week after the steroid induction and entecavir improved them. DIHS itself and the aggravation of hepatitis B by corticosteroid should be kept in mind in cases with dual infection of HBV and HCV treated by antivirals including telaprevir.

[A case of hepatitis E differentially diagnosed from drug-induced liver injury].

A woman in her seventies was admitted because of general fatigue and liver dysfunction (ALT 2565 IU/l). She was diabetic and, 2 months ago, began eating kikuimo (Jerusalem artichoke) containing inulin, which is thought to decrease blood sugar level. Although tests showed no evidence of acute infection of HAV, HBV, HCV, EBV and CMV, a drug-induced lymphocyte stimulation test using kikuimo extract was positive. She was first diagnosed with drug-induced liver injury according to the Japanese diagnostic criteria for the disease. After a non-eventful recovery, her serum was found to be positive for hepatitis E-antibody and RNA (genotype 3), indicating recent, autochthonous infection of HEV. The patient might have been misdiagnosed with drug-induced liver injury unless the serum test for HEV had been performed. We believe that HEV screening is mandatory for accurate diagnosis of hepatitis E and drug-induced liver injury.

Magnetic resonance-guided vacuum-assisted breast biopsy: results in 100 Japanese women.

PURPOSE: The aim of this study was to clarify the frequency of malignancy and the histopathological characteristics of the lesions in patients undergoing magnetic resonance imaging (MRI)-guided vacuum-assisted biopsy (VAB). MATERIALS AND METHODS: A retrospective review of 100 consecutive patients with 102 lesions who had undergone MRI-guided VAB was performed. The biopsies were performed on a 1.5-T MR scanner using a commercially available biopsy system. None of the lesions seen with MRI could be detected by mammography or second-look ultrasonography. RESULTS: The average lesion sizes of the focus, mass, and nonmass lesions before the biopsy were 4.5, 8.2, and 21 mm, respectively. Twelve patients (12%) had lesions located in the deep portion of the breast, close to the pectoral muscle. The biopsy was successfully performed without important side effects in all patients. Histopathological findings were invasive ductal carcinoma in 6 (6%), in situ carcinoma in 28 (27%), and high-risk and benign in 68 (67%). Two high-risk lesions were upgraded to ductal carcinoma in situ (DCIS), and three DCIS lesions were upgraded to invasive ductal carcinoma at surgical excision. CONCLUSION: The high rate of DCIS might be a unique feature among Japanese women. However, MRI-guided VAB is necessary for MRI-only visible suspicious lesions in Japan.

Early results of an endoscopic nipple-sparing mastectomy for breast cancer.

BACKGROUND.: Endoscopic mastectomy has been reportedly associated with smaller scars and greater patient satisfaction; however, few reports on this topic have been made. The purpose of this retrospective study was to examine the early results of endoscopic nipple-sparing mastectomy (ENSM) and to investigate the safety of this procedure. METHODS.: Between January 2002 and December 2005, a total of 87 patients with breast cancer but without skin and nipple involvement, including two cases of bilateral breast cancer, underwent E-NSM. In case of bloody nipple discharge and suspicious extension near the nipple as assessed by magnetic resonance imaging, the major ducts within the nipple were cored (nipple coring). In other cases, nipple coring was not performed. RESULTS.: Of the 89 breasts in 87 patients, 42 had tumors of >2 cm and 80 were diagnosed as having invasive carcinoma. Lymph node involvement was observed in 36 procedures. The overall rate of nipple necrosis was 18% (16 of 89). The rate of nipple necrosis among the procedures with nipple coring was statistically higher than that among those without nipple coring (7 of 17, 41%, vs. 9 of 72, 13%) (P = .01). Nipple involvement was observed in 2.2% (2 of 89). After a median follow-up period of 52 months, distant metastasis was observed in nine cases; no local recurrences occurred in this series. CONCLUSIONS.: E-NSM is an oncologically safe procedure and an acceptable method in selected patients requiring a mastectomy. The higher rate of nipple necrosis may have been the result of a technical problem, indicating the need for continued improvement in nipple coring procedures.

False-negative ultrasound-guided vacuum-assisted biopsy of the breast: difference with US-detected and MRI-detected lesions.

BACKGROUND: The purpose of this study was to retrospectively examine the frequency and causes of a false-negative result of ultrasound (US)-guided vacuum-assisted biopsy. METHODS: A retrospective review was performed of 835 patients with 986 consecutive lesions who had undergone US-guided vacuum-assisted biopsy (US-VAB) using 11-gauge probes. We divided the lesions into two groups (US-detected and MRI-detected lesions). The sizes of the lesions on US, number of cores taken, rates of repeat biopsy, and the false-negative rate were compared between the two groups. RESULTS: The overall false-negative rate of US-VAB was 7.4% (13/175). The final number of malignant pathologic diagnoses was 175 (18%), including 13 false-negative lesions and 6 upgraded high-risk lesions. The false-negative rate for MRI-detected lesions (26%; 8/31) was significantly higher than that for US-detected lesions (3.5%; 5/144) (P = 0.0002). The causes of a false-negative result in the case of US-detected lesions were considered to be technical error in two cases and difficulty in histologic interpretation in three cases. The average size, as measured by US, average number of core samples, and repeat biopsy rate of US-detected lesions and MRI-detected lesions were 11 vs 9.7 mm (P = 0.0005), 13 vs 13 (P = NS), and 7.0% (43/611) vs 9.4% (18/191) (P = NS), respectively. CONCLUSION: The high false-negative result for MRI-detected lesions might arise from the difficulties in MRI-US correlation, which indicates the need for MRI-guided biopsy.

Early results of an endoscopic nipple-sparing mastectomy for breast cancer.

BACKGROUND: Endoscopic mastectomy has been reportedly associated with smaller scars and greater patient satisfaction; however, few reports on this topic have been made. The purpose of this retrospective study was to examine the early results of endoscopic nipple-sparing mastectomy (E-NSM) and to investigate the safety of this procedure. METHODS: Between January 2002 and December 2005, a total of 87 patients with breast cancer but without skin and nipple involvement, including two cases of bilateral breast cancer, underwent E-NSM. In case of bloody nipple discharge and suspicious extension near the nipple as assessed by magnetic resonance imaging, the major ducts within the nipple were cored (nipple coring). In other cases, nipple coring was not performed. RESULTS: Of the 89 breasts in 87 patients, 42 had tumors of >2 cm and 80 were diagnosed as having invasive carcinoma. Lymph node involvement was observed in 36 procedures. The overall rate of nipple necrosis was 18% (16 of 89). The rate of nipple necrosis among the procedures with nipple coring was statistically higher than that among those without nipple coring (7 of 17, 41%, vs. 9 of 72, 13%) (P = .01). Nipple involvement was observed in 2.2% (2 of 89). After a median follow-up period of 52 months, distant metastasis was observed in nine cases; no local recurrences occurred in this series. CONCLUSIONS: E-NSM is an oncologically safe procedure and an acceptable method in selected patients requiring a mastectomy. The higher rate of nipple necrosis may have been the result of a technical problem, indicating the need for continued improvement in nipple coring procedures.

Preoperative MRI marking technique for the planning of breast-conserving surgery.

BACKGROUND: When performing breast-conserving surgery (BCS), it is essential to achieve a complete resection of the tumor while preserving the cosmetic outcome. The aim of this study was to evaluate the accuracy of a MRI marking technique for planning of BCS. METHODS: A retrospective review was performed of 14 consecutive patients who underwent MRI in the supine position (supine MRI) using a MRI marking technique. The preoperative histopathological diagnosis was ductal carcinoma in situ in 11 and invasive ductal carcinoma in 3. All of the patients with invasive ductal carcinoma were treated with neoadjuvant chemotherapy. The pills of Breath Care used as MRI markers were placed in the Penrose drain with 2-cm intervals, and drains were put on the resection lines as determined by ultrasonography (US). The final resection lines were modified using information obtained by supine MRI. The rate of the margin-tumor distance (RMTD: longer margin-tumor distance/shorter margin-tumor distance) was calculated. RESULTS: Thirteen patients (93%) needed modification of the first resection line, whereas one patient (7%) needed no modification. Twelve patients (86%) had negative margins, but two patients (14%) had positive margins: one patient had a medial margin, while the other had a distal margin. One patient showed a pathologically complete response after chemotherapy; the RMTD was not evaluated. Among the 12 patients with medial and lateral negative margins, the medial and lateral margin-tumor distances ranged from 1.0 to 3.5 cm (average 2.1 cm), and the RMTD ranged from 1 to 3.0 (average 1.5). CONCLUSION: Our MRI marking technique may be useful for evaluating the extent of the tumor as determined by the US examination in difficult cases.

MR-guided vacuum-assisted breast biopsy: is it an essential technique?

BACKGROUND: In the United States and Europe, MR-guided vacuum-assisted biopsy (VAB) is required for MR-only visible suspicious lesions that cannot be identified with mammography or ultrasonography. However, it is controversial as to whether MR-guided VAB is essential or not in Japan. The purpose of this study was to clarify the frequency of malignancy among the patients that underwent MR-guided VAB, and to discuss the need for this technique in Japan. METHODS: This study was approved by the Institutional Review Board of our hospital. A retrospective review was performed of 30 consecutive patients who had undergone MR-guided 11-gauge VAB. The biopsies were performed on a 1.5 T MR scanner using a commercially available biopsy system. All lesions seen with MRI could not be detected by mammography and second-look ultrasonography. RESULTS: All 30 lesions were assessed as category 4 or 5. The average lesion size of a mass enhancement before biopsy was 0.7 cm, and the average lesion size of a non-mass-like enhancement was 2.3 cm. The average number of cores of VAB was 19. The median time required to perform the VAB procedure was 35 min. The biopsy was successfully performed without important side effects in all patients. Histopathological findings were invasive ductal carcinoma in one (3%); ductal carcinoma in situ (DCIS) in seven (23%); and benign in 22 (73%). In one case, atypical ductal hyperplasia at VAB was upgraded to DCIS at surgical excision. CONCLUSION: MR-guided VAB can be performed safely and it is needed for MR-only visible suspicious lesions in Japan.

Monitoring of early response to neoadjuvant chemotherapy in breast cancer with (1)H MR spectroscopy: comparison to sequential 2-[18F]-fluorodeoxyglucose positron emission tomography.

PURPOSE: To assess the efficacy of (1)H MR spectroscopy (MRS) to evaluate early responses to neoadjuvant chemotherapy in breast cancer patients, as compared to that of the standardized uptake value (SUV) in (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET). MATERIALS AND METHODS: This retrospective study included seven patients with breast cancer who had both single-voxel (1)H MRS and PET/computed tomography (CT) acquired before, during, and after neoadjuvant chemotherapy. RESULTS: The averages of the Choline (Cho) integral value and peak SUV before chemotherapy were 2.5 (range, 1.2-5.3) and 7.5 (range, 1.9-19), respectively. Three cases became negative for both Cho and peak SUV after two cycles of chemotherapy, and one patient became negative before surgery. In the remaining three patients, the curves of both values paralleled the time course of chemotherapy treatment. The difference between Cho and peak SUV before, during, and after chemotherapy was r = 0.65 (P = 0.12), r = 0.80 (P = 0.03), and r = 0.99 (P < 0.001), respectively. The reduction rate (RR) of both values after chemotherapy was also correlated (r = 0.84, P = 0.02). CONCLUSION: A change in the Cho integral value is well correlated with that of peak SUV in the time course of neoadjuvant chemotherapy; thus, breast (1)H MRS is thought to be an alternative to sequential (18)F-FDG PET.

Bilateral breast MR imaging: is it superior to conventional methods for the detection of contralateral breast cancer?

BACKGROUND: Breast MR imaging has emerged as a highly sensitive modality for the imaging of breast tumors. However, there have been no reports concerning the usefulness of bilateral breast MRI to evaluate the contralateral breast in Japan. The purpose of this study was to examine the frequency of primary bilateral breast cancer, and to investigate the role of bilateral breast MRI in the detection of contralateral breast cancer. METHODS: A retrospective review was performed of 556 consecutive women who had undergone surgery for the primary breast cancer. MR imaging was performed on a 1.5-T system. Both the breasts were examined in the coronal plane on the first-, second-, and fourth-phase dynamic images, acquired at 30, 90 s, and 4.5 min, respectively. The affected single breast was sagittally examined on images obtained in the third phase at 3 min. RESULTS: Twenty-four (4.3%) patients had bilateral breast cancer, 14 (2.5%) had synchronous cancer and 10 patients (1.8%) had metachronous cancer. In the 14 cases with synchronous cancer, bilateral breast malignancy was suspected at the time of the initial diagnosis in 6 cases. The detection rate of 18 contralateral breast cancer cases by only MMG, only US, MMG and US, and MRI were 50% (9/18), 67% (12/18), 78% (14/18) and 100% (17/17), respectively. For 8 of these cases with a second synchronous cancer, the corresponding rates were 75, 88, 100 and 100%, respectively. For the 10 cases with a second metachronous cancer, the rates were 30, 50, 60 and 100%, respectively. CONCLUSION: Bilateral breast MRI is a more sensitive for the detection of contralateral breast cancers compared with conventional imaging methods. In particular, bilateral MRI also allows detection of metachronous contralateral cancers at an earlier stage during the postoperative follow-up period.