Peritumoral Fat Content Identified Using Iterative Decomposition of Water and Fat with Echo Asymmetry and Least-squares Estimation (IDEAL) Correlates with Breast Cancer Prognosis.

PURPOSE: Adipocytes around aggressive breast cancer (BC) are less lipid different from naive adipocytes (cancer-associated adipocytes, CAAs), and peritumoral edema caused by the release of cytokines from CAAs can conduce to decrease the peritumoral fat proportion. The purpose of this study was to correlate peritumoral fat content identified by using iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) with lymph node metastasis (LNM) and recurrence-free survival (RFS) in BC patients and to compare with T2-weighted (T2WI) and diffusion-weighted images (DWI) analyses. METHODS: This retrospective study consisted of 85 patients who were diagnosed with invasive carcinoma of breast and underwent breast MRI, including IDEAL before surgery. The scan time of fat fraction (FF) map imaging using IDEAL was 33s. Four regions of interest (ROIs), which are 5 mm from the tumor edge, and one ROI in the mammary fat of the healthy side were set on the FF map. Then average peritumoral FF values (TFF), average FF values on the healthy side (HFF), and peritumoral fat ratio (PTFR, which is defined as TFF/HFF) were calculated. Tumor apparent diffusion coefficient (ADC) values were measured on ADC map obtained by DWI. Peritumoral edema was classified into three grades based on the degree of signal intensity around the tumor on T2WI (T2 edema). RESULTS: The results of stepwise logistic regression analysis for four variables (TFF, PTFR, T2 edema, and ADC value) indicated that TFF and T2 edema were significant factors of LNM (p < 0.01). RFS was significantly associated with TFF (p = 0.016), and 47 of 49 (95.9%) patients with TFF more than 85.5% were alive without recurrence. CONCLUSION: Peritumoral fat content identified by using IDEAL is associated with LNM and RFS and may therefore be a useful prognostic biomarker for BC.

Laparoscopic approach for port site mass diagnosed as a Schloffer tumor following surgery of ascending colon cancer.

Schloffer tumor is a foreign body granuloma that develops in the subcutaneous layer of the abdomen over several months to several years after surgery due to sutures. Here, we performed a laparoscopic resection for a benign Schloffer tumor that showed positive F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) at the port site of a laparoscopic right hemicolectomy for advanced colon cancer. We report a case in which systemic chemotherapy was avoided as a result of the histological examination following the laparoscopic approach. A 66-year-old female, who underwent laparoscopic right hemi colectomy for stage IIIA ascending colon cancer, was revealed an enhanced mass at the right side of the abdominal subcutaneous layer. PET examination showed a high accumulation of FDG. Laparoscopic tumor resection was performed. Pathological findings reported the formation identical to the Schloffer tumor. Schloffer tumor, which is rare, should be considered as one of the differential diagnoses for tumor with FDG-PET positivity at the port site during the postoperative surveillance period of colorectal cancer.

Metastatic Invasive Lobular Carcinoma of the Breast Presenting Peritoneal Metastasis with Bilateral Ureteral Obstruction.

The most common sites for recurrence of breast cancer are the lungs, liver, and bones. The frequency of peritoneal, gastrointestinal metastasis is significantly lower than those, and bilateral ureteral obstruction caused by peritoneal metastasis is relatively rare. A 66-year-old woman was referred to our hospital because of appetite loss and frequent urination. She was on adjuvant hormonal therapy for local recurrence of right breast cancer. She was diagnosed with bilateral ureteral obstruction due to extramural compression. Exploratory laparoscopy revealed omental cake and peritoneal nodules of which pathological examination showed peritoneal metastasis of invasive lobular carcinoma. Peritoneal metastases from breast cancer are unusual and consequently difficult to identify without non-invasive tools. Exploratory laparoscopy revealed that the cause of hydronephrosis in this case was peritoneal metastasis of invasive lobular carcinoma. Clinical history and histological study play a pivotal role in determining the correct diagnosis.

iTriangular Stapling Technique: A Novel Reconstruction Method and Clinical Outcomes of Cervical Esophagogastric Anastomosis after Esophagectomy.

BACKGROUND: We herein report the feasibility and safety of cervical end-to-end anastomosis by the iTriangular stapling technique (iTST), which was developed as an extension of the triangular stapling technique (TST) after minimally invasive esophagectomy (MIE). METHODS: A total of 45 patients with thoracic esophageal cancer who underwent reconstruction with cervical esophagogastric anastomosis by iTST using a linear stapler after MIE between January 2016 and January 2019 were retrospectively reviewed. We modified and improved upon the TST by adding a 1- to 2-cm vertical incision on the anterior wall of the remnant esophageal stump to enlarge the anastomotic lumen and thereby reduce the risk of anastomotic stenosis. The short-term patient outcomes were determined to assess the safety and feasibility of our procedures. RESULTS: The median operating time was 686 (range, 319-1110) minutes, and the median blood loss was 170 (range, 5-1180) ml. There were no cases of anastomotic stenosis in this study, although 2 patients (4.4%) developed minor anastomotic leakage. A case (2.2%) of tracheal fistula due to the apex of the triangular anastomosis was resolved simply by delaying the patient's oral intake. The mean length of the hospitalization was 21 days. CONCLUSIONS: The iTST provides a larger lumen unlimited by the size of the esophagus in cervical esophagogastric anastomosis. This technique is feasible, and sufficient short-term results have been achieved. Further studies with the accumulation of more cases will be required to prove the benefits of iTST for reconstruction after MIE.

Peritumoral Fat Content Correlates with Histological Prognostic Factors in Breast Carcinoma: A Study Using Iterative Decomposition of Water and Fat with Echo Asymmetry and Least-Squares Estimation (IDEAL).

PURPOSE: To correlate peritumoral fat content using iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) with histologic prognostic factors in breast carcinoma. MATERIALS AND METHODS: This study consisted of 100 patients who were diagnosed with invasive carcinoma of breast and underwent breast MRI including IDEAL before surgery. The scan time of IDEAL fat fraction (FF) map imaging was 33 s. Four regions of interests (ROIs), which are a distance of 5 mm from the tumor edge, and one ROI in the mammary fat of the healthy side were set on the FF map. Then average peritumoral FF values (FFt), average FF values in the healthy side (FFh), and peritumoral fat ratio (pTFR: defined as FFt/FFh) were calculated. Histologically, the presence of lymph node metastasis and the MIB-1 index were evaluated. RESULTS: FFt and pTFR for breast carcinoma with lymph node metastasis (79.27 ± 10.36 and 0.897 ± 0.078) were significantly lower than those without (86.23 ± 4.53 and 0.945 ± 0.032) (P < 0.001 and P = 0.005). Spearman rank correlation suggested that the FFt correlated with the MIB-1 index (r = -340, P = 0.001). CONCLUSION: Quantification of peritumoral fat using IDEAL-iron quantification is associated with the histologic prognostic factors, and may be a practical tool for therapeutic strategy of breast carcinoma.

The prognostic significance of the expression of monocarboxylate transporter 4 in patients with right- or left-sided colorectal cancer.

AIM: Monocarboxylate transporter 4 (MCT4) is a proton pump that exchanges lactate through the plasma membrane. The present study investigated the clinical significance of the expression of MCT4 in patients with right- or left-sided colorectal cancer (CRC). METHODS: Surgical specimens from 237 CRC patients were immunohistochemically stained with polyclonal anti-MCT4 antibodies. The relationships among the MCT4 expression, the clinicopathological factors, and the prognosis were evaluated. RESULTS: Thirty-six (62.1%) of 58 patients with right-sided CRC and 95 (53.1%) of 179 patients with left-sided CRC showed the high expression of MCT4. The MCT4 expression was significantly correlated with gender and lymph node metastasis in patients with right-sided CRC, and size, depth of invasion, distant metastasis, and tumor-node-metastasis stage in patients with left-sided CRC. A univariate analysis demonstrated that the expression of MCT4 was a significant prognostic factor in both right- and left-sided CRC patients. A multivariate analysis demonstrated the expression of MCT4 was a significantly independent prognostic factor in patients with left-sided CRC, but not in those with right-sided CRC. CONCLUSIONS: Our results suggest that the high expression of MCT4 is a useful marker for tumor progression and a poor prognosis in CRC patients, especially those with left-sided CRC.

[A Case of Carcinoma Showing Thymus-Like Differentiation (CASTLE) of the Thyroid].

The case presented herein was a 70-year-old woman who had no compliant, but had a mass in the lower part of the right lobe of the thyroid detected by ultrasound (US). The US image of the tumor, measuring 13 mm in diameter, showed a low and heterogeneous internal echo level with calcification and an irregular margin. The tumor appeared to extend to the adjacent sternothyroid muscle, and cervical lymph node swelling was detected in a computer tomography (CT) image, but no metastatic lesion was found by positron emission tomography (PET)-CT. In a fine needle aspiration cytology of the tumor, papillary thyroid carcinoma was suggested because of the atypical epithelial cells having some changes other than intranuclear inclusion bodies. A subtotal thyroidectomy and central neck lymph node dissection were performed. The excised tumor was histologically composed of irregular nests or sheets of atypical squamoid epithelial cells with some ductal structures that leached to the sternothyroid muscle and involved the right lower parathyroid gland. Carcinoma showing thymus-like differentiation (CASTLE) was diagnosed histopathologically and immunohistochemically with the following immunohistochemical results: Cluster of differentiation 5 (CD5) (+), tumor protein p63 (p63) (+), KIT proto-oncogene receptor tyrosine kinase (c-KIT(CD117)) (+), thyroglobulin (-), and thyroid transcription factor-1 (TTF-1) (-). CASTLE is a rare carcinoma of the thyroid that architecturally resembles thymic epithelial tumors. Many CASTLE patients have been misdiagnosed as other carcinomas, such as anaplastic carcinoma, poorly differentiated carcinoma or squamous cell carcinoma of the thyroid. Immunohistochemical examination, including CD5 played an important role in the final diagnosis of CASTLE, although the distinction from diagnosis as squamous cell carcinoma or mucoepidermoid carcinoma in Hematoxylin-Eosin staining was challenging in our case. Nodal metastasis and perithyroidal tumor extension of CASTLE can predict its worse prognosis. Thus, at least careful follow-up studies are mandatory in cases of CASTLE.

Clinical performance metrics of 3D stereoscopic digital mammography compared with 2D digital mammography: observer study.

OBJECTIVE: To assess the clinical performance of three-dimensional stereoscopic digital mammography (3DsDM) compared with two-dimensional digital mammography (2DDM) for breast lesion diagnosis with jackknife free-response receiver operating characteristics (JAFROC) observer study. METHODS: 40 pairs of standard-dose 2DDM and their 3DsDM images were used for an observer performance study. A total of 18 lesions were identified as the reference standard of actionable breast lesions (Breast Imaging Reporting and Data System Category 3 or more) by two breast radiologists. Ratings and locations of "lesions" determined by observers were utilized for assessing the statistical significance of differences between eight radiologists' performances with the 2DDM images and with the 3DsDM images in jackknife free-response receiver operating characteristic analysis. RESULTS: The average figure-of-merit values for all radiologists increased to a statistically significant degree, from 0.859 with the 2DDM images to 0.936 with the 3DsDM images (p < 0.001). The average sensitivity for detecting actionable lesions was improved from 74.3 to 92.4% at a false-positive rate of 0.2 per case by use of the 3DsDM images. The mean reading time per case with 2DDM images was not significantly different from that with 3DsDM images. CONCLUSION: The use of 3DsDM would improve the observer performance for breast lesion without considerably extending the reading time. Advances in knowledge: Use of 3DsDM improves radiologists' performance for breast lesion detection.

A Case of Matrix-Producing Carcinoma of the Breast.

A 61-year-old woman was referred to our hospital because of a right breast mass. A 19 mm hard mass was palpable in the A area of the right breast. A contrast-enhanced MRI showed rim enhancement at the peripheral region of the tumor, which was thought to represent the carcinoma component mainly at the periphery and the matrix component inside the tumor. A low density mass with rim enhancement at the peripheral region was observed in a contrast-enhanced CT, the same as in the MRI. Neither axillary lymph node metastasis nor distant metastasis was observed. A core needle biopsy of the tumor lead to a diagnosis of matrix-producing carcinoma (MPC). A breast-conserving mastectomy with sentinel lymph nodes biopsy was performed on the right breast MPC (T1c, N0, M0 Stage I). Histopathologically, the tumor demonstrated overt carcinoma with direct transition to a cartilaginous or osseous matrix and lacked an intervening spindle cell component. Immunohistochemistry showed estrogen receptor (ER) (-), progesterone receptor (PgR) (-), human epidermal growth factor receptor 2 (HER2) (-), and Ki67 index of 50%, so-called triple negative breast cancer. The tumor was also positive for SRY-related HMG box-9 (SOX9), which is a useful marker of chondroid differentiation in normal and neoplastic tissues. The patient lived free from recurrence for 5 years, even though her adjuvant therapy was only radiation therapy without adjuvant chemotherapy. MPC is an uncommon and relatively rare variant of metaplastic carcinoma, and the prognosis for patients with MPC is poorer than that for patients with ordinary breast cancer. Here we report a case of MPC of the breast with characteristic rim enhancement in contrast-enhanced MRI and CT. The intrinsic subtype and prognosis of MPC is controversial, and then we may need more experience with MPC cases.

Evaluation of the R2* value in invasive ductal carcinoma with respect to hypoxic-related prognostic factors using iterative decomposition of water and fat with echo asymmetry and least-squares emission (IDEAL).

OBJECTIVE: To correlate the R2* value obtained by iterative decomposition of water and fat with echo asymmetry and least-squares emission (IDEAL) with fibrotic focus (FF), microvessel density and hypoxic biomarker (HIF-1α) in breast carcinoma. METHODS: Forty-two patients who were diagnosed with invasive ductal carcinoma (IDC) of the breast underwent breast MRI including IDEAL before surgery. The entire region of interest (ROI) was delineated on the R2* map, and average tumour R2* value was calculated for each ROI. Histological specimens were evaluated for the presence of FF, the microvessel density (the average microvessel density and the ratio of peripheral to central microvessel density), and the grading of HIF-1α. RESULTS: FF was identified in 47.6% (20/42) of IDCs. Average R2* value for IDC with FF (42.4±13.2 Hz) was significantly higher than that without FF (28.5±13.9 Hz) (P = 0.01). Spearman rank correlation suggested that the average R2* value correlated with the grade of HIF-1α and the ratio of peripheral to central microvessel density for IDCs (P < 0.001). CONCLUSION: Quantification of tumour R2* using IDEAL is associated with the presence of FF and the overexpression of HIF-1α, and may therefore be useful in predicting hypoxia of breast carcinoma. KEY POINTS: • R2* value obtained by IDEAL correlates with the overexpression of HIF-1α. • R2* value obtained by IDEAL is associated with fibrotic focus. • R2* quantification may be useful in predicting hypoxia of breast carcinoma.

Routine intraoperative cholangiography during single-incision laparoscopic cholecystectomy: a review of 196 consecutive patients.

BACKGROUND: Single-incision laparoscopic cholecystectomy (SILC) has been increasingly performed as a potentially less invasive alternative to standard laparoscopic cholecystectomy. However, recent evidences suggest a higher incidence of complications, notably bile duct injuries, in SILC. We reviewed our experiences with routine intraoperative cholangiography (IOC) during SILC to investigate its feasibility and usefulness. METHODS: Among 228 patients who underwent SILC at our institution from September 2009 to July 2012, a total of 196 patients in which an IOC was attempted were retrospectively reviewed. RESULTS: IOC was successful in 178 of 196 patients, yielding a success rate of 90.8 %. There were no IOC-related complications. Common bile duct (CBD) stones were detected by IOC in 16 patients (8.2 %), all of which were treated by subsequent single-incision laparoscopic CBD exploration or postoperative endoscopic retrograde cholangiopancreatography with stone extraction. In addition, IOC revealed filling defects in the cystic duct (four patients) and poor passage of contrast medium into the duodenum (one patient). In one patient with severe acute cholecystitis, cholangiography via an endoscopic nasobiliary drainage tube revealed misinterpretation of CBD as cystic duct. CONCLUSIONS: We, thus, conclude that routine IOC during SILC is feasible and useful to detect biliary stones and to gain an accurate picture of biliary anatomy.

Prognostic significance of monocarboxylate transporter 4 expression in patients with colorectal cancer.

Cancer cells generally have a high rate of glycolysis and produce larger quantities of lactate as compared to the surrounding normal cells. Monocarboxylate transporter 4 (MCT4) is one of the proton pumps exchanging the lactate through the plasma membrane. The prognostic significance of MCT4 expression has not been evaluated in patients with colorectal cancer (CRC). Surgical specimens from 105 CRC patients were immunohistochemically stained using a polyclonal anti-MCT4 antibody. The relationships among the MCT4 expression, clinicopathological factors and prognosis were evaluated. A total of 53 (50.5%) of the 105 patients with CRC were determined to have tumors positive for MCT4 expression. The expression of MCT4 significantly correlated with the tumor size, depth of invasion, lymph node metastasis, distant metastasis and TNM staging. The survival rate of the patients who were positive for MCT4 expression was significantly lower than that of patients with negative MCT4 expression. Positive MCT4 expression was a significantly poor prognostic factor, as determined by both univariate and multivariate analyses. Therefore, positive MCT4 expression appears to be a useful marker for tumor progression and prognosis in patients with CRC.

[A case of small cell lung cancer (extensive disease) with liver metastasis acquiring stable disease by hepatic arterial infusion chemotherapy].

The patient was a 58-year-old male with small cell lung cancer [T2N1M1 (HEP) ED case] who was treated systemic chemotherapy with 2 courses of CDDP+CPT-11 and 3 courses of CBDCA+PTX. After 5 courses of chemotherapy, the total response was stable disease (SD). Because the primary lesion had achieved a minor response, however, liver metastasis evidenced no change. Because of his good performance status, he was immediately treated by hepatic arterial infusion chemotherapy ( HAI) using CPT-11 to control the liver metastasis. After the HAI of weekly CPT-11 during eleven months until progression of primary lung lesion, no change in size of the liver metastasis was recognized with decreasing ProGRP (18,400 -->5,800). HAI is considered very useful for disease control without progression and for good quality of life.

A long-term survivor with late-onset-repeated pulmonary metastasis of a PEComa.

A 59-year-old male underwent a surgical resection of a retroperitoneum tumor in 1990 that was diagnosed as leiomyoblastoma. Thereafter he demonstrated pulmonary metastases followed by a total of 3 pulmonary resections from 1995 to 1997. In 2008, he was incidentally found to have a tumor in the left lower lobe, which was diagnosed as a metastatic perivascular epithelioid cell (PEComa) neoplasm. Retrospectively, a primary tumor and pulmonary metastases were also diagnosed as PEComa. We experienced late-onset repeated pulmonary metastasis of a PEComa.

Chemopreventive effect of 4-[3,5-Bis(trimethylsilyl) benzamido] benzoic acid (TAC-101) on MNU-induced colon carcinogenesis in a rat model.

PURPOSE: 4-[3,5-Bis(trimethylsilyl)benzamido] benzoic acid (TAC-101) is a novel retinobenzoic acid derivative. The chemopreventive effect and the mechanism of action of TAC-101 were investigated using a rat chemical colon carcinogenesis model. MATERIALS AND METHODS: Colon tumors were induced using intra-rectal instillation of N-methyl-N-nitrosourea (MNU) in F344 rats. These rats were divided into five groups, control, high dose (TAC-101 8 mg/kg)-long period (four weeks), high dose-short period (one week), low dose (TAC-101 0.8 mg/kg)-long period and low dose-short period. After the large bowels were resected at 20 weeks, the number of aberrant crypt foci (ACF) and tumors in the colon were counted. Proliferating cell nuclear antigen (PCNA) positive index, apoptotic index (AI) and Fas expression were also evaluated using immunohistochemistry. RESULTS: The tumor incidence and the tumor number in the high dose-long period group were decreased in comparison to those in the other groups, but not significantly. However, the number of ACF or PCNA positive indices in the high dose-long period group was significantly decreased in comparison to that in the other groups. On the other hand, the AI and the Fas expression pattern in the tumor and the normal appearing mucosa were not changed in any of the groups. CONCLUSION: TAC-101 might inhibit MNU induced colon carcinogenesis via a decrease of ACF. The mechanism of this chemoprevention may be related to a reduction in cell proliferation, but is not directly associated with apoptosis.

High plasma brain natriuretic peptide levels in stable COPD without pulmonary hypertension or cor pulmonale.

BACKGROUND: Early diagnosis of chronic obstructive pulmonary disease (COPD) with latent pulmonary hypertension (PH) and cor pulmonale is important because the prognosis of this condition is poor. OBJECTIVE: To investigate the utility of brain natriuretic peptide (BNP) for prognostication of COPD, plasma BNP was measured in patients with COPD without symptoms or physical findings of PH or cor pulmonale. METHODS: Plasma BNP was measured in 60 patients with COPD, 10 asthmatics, and 30 healthy subjects. Echocardiography, arterial blood gas analysis, and spirometry were also performed. Mortality and exacerbation were compared between COPD patients with high and low plasma BNP levels over a 3-year follow-up period. RESULTS: Plasma BNP (mean +/- SEM, pg/mL) in COPD patients (41.0+/-6.6) was significantly higher than in normal subjects (14.8+/-2.7) and asthmatics (17.4+/-4.5) (p<0.0001 and p<0.05, respectively). No significant correlations were observed between plasma BNP level and pulmonary function or hypoxia. There was, however, a significant correlation between plasma BNP level and % ejection fraction (r=-0.41, p=0.0197) and pulmonary artery systolic pressure (r=0.5, p=0.004). The period until initial COPD exacerbation in subjects with a high plasma BNP level was significantly shorter (p<0.05). Plasma BNP level during exacerbations (79.9+/-16.2) was also significantly higher than during stable disease (41.2+/-8.7) (p=0.004). CONCLUSION: We suggest that plasma BNP is a non-invasive biomarker that can be used as a screening parameter for latent PH and left ventricular dysfunction, and also as a predictor of exacerbation in stable COPD.

[A case of low grade ductal carcinoma in situ of the breast with difficulties in making the preoperative diagnosis after detection by FDG-PET].

A 56-year-old woman underwent FDG-PET screening, which demonstrated delayed-phase uptake in the lower part of the left breast. The findings of mammography, ultrasonography, MRI and cytological examination were compatible with ductal carcinoma in situ (DCIS), but core needle biopsy showed no evidence of malignancy. Therefore, partial resection of the left breast with sentinel lymph node biopsy was performed to make a definite diagnosis. Histological examination showed that this tumor was low grade DCIS. FDG-PET is a very useful examination to detect malignant diseases, but it is quite difficult to distinguish them from benign ones. It is suggested that delayed-phase uptake of FDG-PET is useful for diagnosis of DCIS.

Prognostic significance of the local expression of interleukin-12 in patients with advanced gastric cancer.

BACKGROUND: Interleukin (IL)-12 is a heterodimeric cytokine that exhibits potent antitumor and antimetastatic activities. Very few studies have so far investigated the local expression of L-12 in tumor specimens of gastric cancer. The purpose of this study was to investigate the immunohistochemical expression of IL-12 in patients with gastric cancer. PATIENTS AND METHODS: IL-12 was immunohistochemically stained using monoclonal antihuman IL-12 antibody (1-1A4) in surgical specimens of 117 gastric cancer patients. The IL-12-positive cell density was calculated. The relationships among the IL-12-positive cell density, clinicopathological factors and 5-year survival rate were evaluated. RESULTS: Among the patients (n=117), the 5-year survival rate after surgery was not statistically different between the patients with high and low IL-12 positive cell-density. However, in the patients with advanced gastric cancer (n=85), those with a high IL-12-positive cell density showed a significantly better prognosis in comparison with those with a low IL-12-positive cell density (p=0.0104). A multivariate analysis indicated that the IL-12-positive cell density and TNM stage are significant prognostic factors. CONCLUSION: IL-12-positive cell density may be a significant independent prognostic factor in surgical specimens of advanced gastric cancer.

Recurrent thrombotic thrombocytopenic purpura in a patient with systemic lupus erythematosus.

We encountered a 39-year-old female patient with systemic lupus erythematosus (SLE) in whom thrombotic thrombocytopenic purpura (TTP) recurred. The patient was successfully treated with corticosteroid in combination with immunosuppressive agents. Because TTP complicating SLE is more resistant to treatment than idiopathic TTP, prompt diagnosis and efficacious initial treatment are critical.

4- [3,5-bis(trimethylsilyl)benzamido] benzoic acid (TAC-101) induced fas expression and activated caspase-3 and -8 in a DLD-1 colon cancer cell line.

BACKGROUND: 4-[3,5-Bis (trimethylsilyl) benzamido] benzoic acid (TAC-101) is a novel retinobenzoic acid derivative which has a specific binding affinity to the retinoic acid receptors (RAR)alpha and RARbeta. Using time-dependent FACScan analysis, it was observed that TAC-101 induced apoptosis in a DLD-1 human colon cancer cell line. In this study, the induction of apoptosis-related proteins and the activities of caspases in a DLD-1 cell line under medication with TAC-101 were investigated. MATERIALS AND METHODS: DLD-1 cells were cultured with different concentrations of TAC-101 for 12, 24 and 48 h. The expressions of Fas, TNF-R1, DR3, bcl-2, Bax and Bid were measured using a Western blot analysis. The activities of caspase-3, -8 and -9 were measured using a colorimetric protease assay kit. RESULTS: The Western blot analysis showed that TAC-IO1 had almost no effect on the level of Bcl-2, Bax or Bid protein. Although TAC-101 did not change the expression of TNF-R1 and DR3, TAC-101 increased the expression of Fas in both a time- and a dose-dependent manner. A 3-fold increase in caspase-3 activity and a 1.5-fold increase in caspase-8 activity were observed in cells treated with TAC-101 in comparison to the control cells (p<0.01). CONCLUSION: Our data indicate that the death receptor root of the apoptotic signal transduction in DLD-1 cells mainly participates in the apoptotic induction of TAC-101. Because the compounds inducing apoptotic activity are frequent targets of cancer therapy, TAC-101 may be a good candidate for use in the treatment of colon cancer.