Omission of axillary lymph node dissection in patients who underwent total mastectomy with 1 or 2 metastatic lymph nodes

Purpose@#Sentinel lymph node biopsy (SLNB) is the standard axillary procedure in early breast cancer patients. In a randomized trial, the survival rates were not different when axillary lymph node dissection (ALND) was omitted in patients with 1 or 2 lymph node metastases who underwent breast conserving surgery. This study aimed to compare the outcomes in patients who underwent total mastectomy (TM) with 1 or 2 metastatic nodes according to the types of axillary surgery. @*Methods@#In total, 79,058 patients registered in the Korean Breast Cancer Society database who underwent TM were included in the analysis. The inclusion criteria were history of TM and SLNB, pathologic T stage 1 or 2, clinically negative axillary lymph nodes, 1 or 2 metastatic axillary lymph nodes, no radiation therapy, and no neoadjuvant therapy. We divided the patients into the SLNB only and SLNB + ALND groups. The groups were matched by propensity scores. We retrospectively analyzed the differences in the overall survival (OS) between the 2 groups. @*Results@#A total of 883 patients were matched in a 1:4 ratio for the SLNB only and SLNB + ALND groups in the cohort from 1999 to 2014. There were no significant differences in OS between the 2 groups (P = 0.413). Subgroup analysis revealed a significant survival benefit in the SLNB + ALND group in the T2 subgroup (P = 0.013). @*Conclusion@#OS did not differ between the 2 groups in early breast cancer patients with 1 or 2 metastatic axillary lymph nodes who underwent TM. Omission of ALND may be considered in selected patients.

Omission of axillary lymph node dissection in patients who underwent total mastectomy with 1 or 2 metastatic lymph nodes

Purpose@#Sentinel lymph node biopsy (SLNB) is the standard axillary procedure in early breast cancer patients. In a randomized trial, the survival rates were not different when axillary lymph node dissection (ALND) was omitted in patients with 1 or 2 lymph node metastases who underwent breast conserving surgery. This study aimed to compare the outcomes in patients who underwent total mastectomy (TM) with 1 or 2 metastatic nodes according to the types of axillary surgery. @*Methods@#In total, 79,058 patients registered in the Korean Breast Cancer Society database who underwent TM were included in the analysis. The inclusion criteria were history of TM and SLNB, pathologic T stage 1 or 2, clinically negative axillary lymph nodes, 1 or 2 metastatic axillary lymph nodes, no radiation therapy, and no neoadjuvant therapy. We divided the patients into the SLNB only and SLNB + ALND groups. The groups were matched by propensity scores. We retrospectively analyzed the differences in the overall survival (OS) between the 2 groups. @*Results@#A total of 883 patients were matched in a 1:4 ratio for the SLNB only and SLNB + ALND groups in the cohort from 1999 to 2014. There were no significant differences in OS between the 2 groups (P = 0.413). Subgroup analysis revealed a significant survival benefit in the SLNB + ALND group in the T2 subgroup (P = 0.013). @*Conclusion@#OS did not differ between the 2 groups in early breast cancer patients with 1 or 2 metastatic axillary lymph nodes who underwent TM. Omission of ALND may be considered in selected patients.

Recurrent Ipsilateral Breast Sparganosis: A Case Report

Sparganosis is a rare parasitic infection that can infect the abdominal wall, extremities, urogenital system, and/or central nervous system. Because the incidence of sparganosis is less than 2% of all reported cases of sparganosis, early diagnosis of sparganosis is difficult. Breast sparganosis has characteristic radiologic findings. Complete surgical removal is the treatment of choice and has the benefit of producing a definite diagnosis. Herein, we would report a case of recurrent breast sparganosis that occurred two years after surgical excision of worms from the ipsilateral breast.

The Usefulness of Intraoperative Circumferential Frozen-Section Analysis of Lumpectomy Margins in Breast-Conserving Surgery / 한국유방암학회지

PURPOSE: Intraoperative frozen-section analysis of the lumpect-omy margin during breast-conserving surgery (BCS) is an excellent method in obtaining a clear resection margin. This study aimed to investigate the usefulness of intraoperative circumferential frozen-section analysis (IOCFS) of lumpectomy margin during BCS for breast cancer, and to find factors that increase the conversion into mastectomy. METHODS: From 2007 to 2011, 509 patients with breast cancer underwent IOCFS during BCS. The outer surfaces of the shaved lumpectomy margins were evaluated. A negative margin was defined as no ink on the tumor. All margins were evaluated using the permanent section analysis. RESULTS: Among the 509 patients, 437 (85.9%) underwent BCS and 72 (14.1%) finally underwent mastectomy. Of the 483 pathologically confirmed patients, 338 (70.0%) were true-negative, 24 (5.0%) false-negative, 120 (24.8%) true-positive, and 1 (0.2%) false-positive. Twenty-four patients (4.7%) among total 509 patients had undetermined margins as either atypical ductal hyperplasia or ductal carcinoma in situ in the first IOCFS. The IOCFS has an accuracy of 94.8% with 83% sensitivity, 99.7% specificity, 93.4% negative predictive value, and 99.2% positive predictive value. Sixty-three cases (12.4%) were converted to mastectomy, the first intraoperatively. Of the 446 (87.6%) patients who successfully underwent BCS, 64 patients received additional excisions and 32 were reoperated to achieve clear margin (reoperation rate, 6.3%). Twenty-three of the reoperated patients underwent re-excisions using the second intraoperative frozen section analysis, and achieved BCS. Nine cases were additionally converted to mastectomy. No significant differences in age, stage, and biological factors were found between the BCS and mastectomy cases. Factors such as invasive lobular carcinoma, multiple tumors, large tumor, and multiple excisions increased the conversion to mastectomy. CONCLUSION: The IOCFS analysis during BCS is useful in evaluating lumpectomy margins and preventing reoperation.

Basic Facts of Breast Cancer in Korea in 2014: The 10-Year Overall Survival Progress / 한국유방암학회지

We, the Korean Breast Cancer Society (KBCS), present the facts and the trends of breast cancer in Korea in 2014. Data on the total number of newly diagnosed patients was obtained from the Korea Central Cancer Registry database, other data were collected from the KBCS online registry database, and the overall survival data of patients were updated from Statistics Korea. A total of 21,484 female patients were newly diagnosed with breast cancer in 2014. The crude incidence rate and the age-standardized incidence rate (ASR) of breast cancer in female patients, including carcinoma in situ, were 83.4 cases and 63.9 cases per 100,000 women, respectively. The ASR showed an annual increase of 6.1% from 1999 to 2014; however, although the increase of the ASR had slowed since 2008, the incidence rate itself continuously increased. The proportion of early breast cancer increased consistently, and the pathological features changed accordingly. While breast-conserving surgery was mainly performed, the proportion of total mastectomy was slightly increased. The total number of breast reconstruction surgeries increased rapidly. The 5-year and 10-year overall survival rates for all stages of breast cancer patients were 91.2% and 84.8%, respectively. The overall survival rate of Korean patients with breast cancer was extremely high, compared with other developed countries. Thus, we consider that the clinical characteristics of breast cancer have changed over the past decade. A nationwide registry data will contribute to a better understanding of the characteristics of breast cancer in Korea.

A case report of 29-year-old male patient with breast carcinoma

Male breast cancer is a rare disease, accounting for about 1% of all breast cancers. Little is known about the etiology of male breast cancer, especially developed in young man. Genetic and hormonal factors have been reported to be involved in its pathogenesis. But, less is known regarding the role of anthropometric or other endocrine risk factors. It's extremely rare for breast cancer to occur in young male patient because male breast cancer generally occur in old patients. A 29-year-old male was diagnosed with breast cancer in our institution who was with diabetes and obesity. There was no specific risk of genetic or hormonal factors for his breast cancer.

Metastatic axillary node ratio predicts recurrence and poor long-term prognosis in patients with advanced stage IIIC (pN3) breast cancer

PURPOSE: Patients with stage IIIC breast cancer are classified as having pathologic nodal stage 3 (pN3) according to the 7th American Joint Committee on Cancer Tumor Node Metastasis (AJCC TNM) staging system. However, the prognosis of patients with this stage is still highly variable. This study was carried out to investigate the validity of metastatic axillary lymph node ratio (mALNR) as a predictor of long-term prognosis in stage IIIC breast cancer. METHODS: Medical records of 297 patients who underwent surgery with more than level II axillary dissection for breast cancer and who were diagnosed with pN3 by pathology between 1990 and 2010, were reviewed. Clinicopathologic variables were evaluated as prognostic factors of disease-free and overall survival by univariate and multivariate analyses. RESULTS: A preliminary analysis revealed the cutoff value of mALNR to be 0.65 (Low65 group vs. High65 group). The mean mALNR was 0.62 (0.16–1.0) and was the most significant independent predictor of disease-free and overall survival on multivariate analysis. The rates of recurrence were significantly different according to mALNR (Low65, 40.3%; High65, 63.0%; P < 0.001). The 10-year disease-free (Low65, 57.0%; High65, 35.0%) and overall (Low65, 64.2%; High65, 38.3%) survival rates decreased significantly with increased mALNR (P < 0.001). CONCLUSION: Patients with stage IIIC breast cancer can be subdivided into subgroups with significantly different long-term prognoses. Our data suggest that the mALNR is an independent risk factor of recurrence and mortality. The mALNR is a valuable prognostic factor to predict the long-term prognosis of stage IIIC breast cancer patients.

The Basic Facts of Korean Breast Cancer in 2013: Results of a Nationwide Survey and Breast Cancer Registry Database / 한국유방암학회지

The Korean Breast Cancer Society (KBCS) has reported a nationwide breast cancer data since 1996. We present a comprehensive report on the facts and trends of breast cancer in Korea in 2013. Data on the newly diagnosed patients in the year 2013 were collected from 99 hospitals by using nationwide questionnaire survey. Clinical characteristics such as stage of cancer, histologic types, biological markers, and surgical management were obtained from the online registry database. A total of 19,316 patients were newly diagnosed with breast cancer in 2013. The crude incidence rate of female breast cancer including carcinoma in situ was 76.2 cases per 100,000 women. The median age at diagnosis was 50 years, and the proportions of postmenopausal women with breast cancer accounted for more than half of total patients. The proportion of early breast cancer increased consistently, and the pathologic features have changed accordingly. Breast-conserving surgery was performed in more cases than total mastectomy in the year. The total number of breast reconstruction surgeries markedly increased approaching 3-fold in last 11 years. According to annual percentile change of invasive cancer incidence, the incidence increased rapidly until 2010. And thereafter the increase of it became steadier. For ductal carcinoma in situ, the incidence consistently increased during the same period without any joinpoint. Analysis of nationwide registry data will contribute to defining of the trends and characteristics of breast cancer in Korea.

The Basic Facts of Korean Breast Cancer in 2012: Results from a Nationwide Survey and Breast Cancer Registry Database / 한국유방암학회지

The Korean Breast Cancer Society has constructed a nationwide breast cancer database through utilization of an online registration program. We have reported the basic facts about breast cancer in Korea in 2012, and analyzed the changing patterns in the clinical characteristics and management of breast cancer in Korea over the last 10 years. Data on patients newly diagnosed with breast cancer were collected for the year 2012 from 97 hospitals and clinics nationwide using a questionnaire survey, and from the online registry database. A total of 17,792 patients were newly diagnosed with breast cancer in 2012. The crude incidence rate of female breast cancer, including invasive cancer and in situ cancer, was 70.7 cases per 100,000 women. The median age at diagnosis was 51 years, and the proportion of postmenopausal women was higher than that of premenopausal women among those diagnosed with breast cancer. The proportion of cases of early breast cancer increased continuously, and breast-conserving surgery was performed in more cases than total mastectomy in that same year. The total number of breast reconstruction surgeries increased approximately 3-fold over last 10 years. The 5-year overall survival rate for all stages of breast cancer patients was extremely high. The clinical characteristics of breast cancer have changed in ways that resulted in high overall survival over the past 10 years in Korea, and the surgical management of the disease has changed accordingly. Analysis of nationwide registry data will contribute to a better understanding of the characteristics of breast cancer in Korea.

The Korean guideline for breast cancer screening

Breast cancer is the second most common malignancy among Korean women. The 2002 National Cancer Center screening guideline breast cancer was revised via an evidence-based approach to provide medical personnel with a standard protocol of screening breast cancer. There is moderate-level evidence that biennial screening mammography in asymptomatic women aged 40 to 69 reduces breast cancer mortality, while low-level evidence suggests that screening mammography in women 70 years or older does not reduce breast cancer mortality. The committee concluded that the current evidence is insufficient to assess the benefits and harms of either ultrasonography or clinical breast examination as screening modalities for breast cancer. Future researches about the benefits and harms of the National Breast Cancer Screening Program in Korea are strongly required because the characteristics of breast cancer in Korea are different from those in the West, especially regarding dense breast. In conclusion, the committee recommends biennial screening mammography in asymptomatic women aged 40 to 69 years (grade B recommendation). The committee recommends selective screening mammography in women 70 years or older according to individual risk and preference (grade C recommendation). The committee neither recommends nor opposes ultrasonography and clinical breast examination as screening modalities (grade I recommendation). Symptomatic and high-risk women, however, should be offered complementary measures including ultrasonography and clinical breast examination under clinical supervision.

Evaluation of the Survival Benefit of Different Chemotherapy Regimens in Patients with T1-2N0 Triple-Negative Breast Cancer / 한국유방암학회지

PURPOSE: This study aimed to evaluate the survival benefit of different adjuvant chemotherapy regimens in patients with T1-2N0 triple-negative breast cancer. METHODS: Of 67,321 patients who were registered in the Korean Breast Cancer Society nationwide database between January 1999 and December 2008, 4,033 patients with T1-2N0 triple-negative breast cancer were included. The overall survival of patients who did not receive adjuvant chemotherapy was compared with those treated with adjuvant anthracycline and cyclophosphamide (AC), 5-fluorouracil, anthracycline, and cyclophosphamide (FAC), or cyclophosphamide, methotrexate, and 5-fluorouracil (CMF). RESULTS: The median follow-up was 52.5 months. Chemotherapy was used in 87.4% of patients; it was used more commonly in patients with T2 tumors, those who were younger, had a higher histologic grade, and who showed lymphovascular invasion. The 5-year cumulative overall survival rate was 95.4%. Younger age, breast-conserving surgery, and adjuvant chemotherapy were significantly associated with improved overall survival. The 5-year cumulative overall survival rate of patients who did not receive adjuvant chemotherapy and those treated with AC, FAC, and CMF were 92.5%, 95.9%, 95.3%, and 95.9%, respectively. On multivariate analysis, the administration of any adjuvant chemotherapy regimen was significantly associated with improved overall survival (p=0.038). No significant difference in survival benefit was observed among the three different treatment groups. CONCLUSION: A standard adjuvant chemotherapy regimen with the least drug-related toxicity might be a reasonable treatment for patients with T1-2N0 triple-negative breast cancer.

Erratum: The Basic Facts of Korean Breast Cancer in 2011: Results of a Nationwide Survey and Breast Cancer Registry Database / 한국유방암학회지

The funding source should be added.

Validation of Risk Assessment Models for Predicting the Incidence of Breast Cancer in Korean Women / 한국유방암학회지

PURPOSE: The Gail model is one of the most widely used tools to assess the risk of breast cancer. However, it is known to overestimate breast cancer risk for Asian women. Here, we validate the Gail model and the Korean model using Korean data, and subsequently update and revalidate the Korean model using recent data. METHODS: We validated the modified Gail model (model 2), Asian American Gail model, and a previous Korean model using screening patient data collected between January 1999 and July 2004. The occurrence of breast cancer was confirmed by matching the resident registration number with data from the Korean Breast Cancer Registration Program. The expected-to-observed (E/O) ratio was used to validate the reliability of the program, and receiver operating characteristics curve analysis was used to evaluate the program's discriminatory power. There has been a rapid increase in the incidence of breast cancer in Korea, and we updated and revalidated the Korean model using incidence and mortality rate data from recent years. RESULTS: Among 40,229 patients who were included in the validation, 161 patients were confirmed to have developed breast cancer within 5 years of screening. The E/O ratios and 95% confidence intervals (CI) were 2.46 (2.10-2.87) for the modified Gail model and 1.29 (1.11-1.51) for the Asian American Gail model. The E/O ratio and 95% CI for the Korean model was 0.50 (0.43-0.59). For the updated Korean model, the E/O ratio and 95% CI were 0.85 (0.73-1.00). In the discriminatory power, the area under curve and 95% CI of the modified Gail model, Asian American Gail model, Korean model and updated Korean model were 0.547 (0.500-0.594), 0.543 (0.495-0.590), 0.509 (0.463-0.556), and 0.558 (0.511-0.605), respectively. CONCLUSION: The updated Korean model shows a better performance than the other three models. It is hoped that this study can provide the basis for a clinical risk assessment program and a future prospective study of breast cancer prevention.

The Basic Facts of Korean Breast Cancer in 2011: Results of a Nationwide Survey and Breast Cancer Registry Database / 한국유방암학회지

Breast cancer is the second most frequent malignancy in Korean women, with a continuously increasing incidence. The Korean Breast Cancer Society has constructed a nationwide breast cancer database through an online registration program. The aim of the present study was to report the fundamental facts on Korean breast cancer in 2011, and to analyze the changing patterns in clinical characteristics and breast cancer management in Korea over the last 10 years. Data on newly diagnosed breast cancer patients, including the total number of cases, age, stage, and type of surgery, for the year 2011 were collected from 84 hospitals and clinics nationwide using a questionnaire survey. Additional data relating to the changing patterns of breast cancer in Korea were collected from the online breast cancer registry database and analyzed. According to nationwide survey data, a total of 16,967 patients were newly diagnosed with breast cancer in 2011. The crude incidence of female breast cancer, including invasive cancer and in situ cancer, was 67 cases per 100,000 women. Analysis of the survey and registry data gave equivalent results in terms of age distribution, stage, and type of surgery. The median age at diagnosis was 50 years, and the proportion of postmenopausal women (51.3%) was higher than that of premenopausal women (48.7%) with breast cancer. The incidence of stage 0 and stage I breast cancer increased continuously over the last 10 years (56.3% in 2011), and breast conserving surgery (65.7%) was performed more frequently than total mastectomy (33.8%). The total number of breast reconstruction surgeries increased approximately 8-fold. We conclude that the clinical characteristics of breast cancer have changed over the past 10 years in Korea, and surgical management has changed accordingly. Analysis of nationwide registry data will contribute to a better understanding of the characteristics of breast cancer in Korea.

The Feasibility of Lateral Minimal Invasive Open Thyroid Lobectomy / 대한내분비외과학회지

PURPOSE: Minimal invasive open thyroidectomy is one option for minimal invasive surgery. The population of planned unilateral lobectomy is on the rise in parallel to the increased incidence of confined papillary thyroid microcarcinomas in Korea. In contrast to other minimal invasive modalities, few studies have examined the surgical outcome of minimal invasive open thyroidectomy. This study compared the lateral minimal invasive open thyroid lobectomy with conventional surgery and endoscopic surgery in terms of the feasibility and safety. METHODS: A retrospective study was performed on 197 patients undergoing a thyroid lobectomy between January 2001 and December 2010. One hundred and three patients underwent a lateral minimal invasive open thyroid lobectomy, 42 patients underwent conventional surgery, and 44 patients underwent endoscopic surgery. RESULTS: The hospitalization period with endoscopic surgery was 6.2 days, which was longer than the 5.3 days with a lateral minimal invasive open thyroid lobectomy (P=0.000). The surgical time was lower in those who underwent a lateral minimal invasive open thyroid lobectomy (88.2 minutes) than in those who underwent conventional surgery (107 minutes, P=0.000) or endoscopic surgery (124.1 minutes, P=0.000). In the patients with a diagnosis of malignancy, the mean number of retrieved LNs was similar in the three groups. CONCLUSION: A lateral minimal invasive open thyroid lobectomy offers advantages, such as a shorter surgical time and hospitalization period than others. This procedure can be a feasible alternative to the conventional or endoscopic approach in selected patients undergoing thyroid lobectomy.

Central Lumpectomy with Resection of the Nipple-areolar Complex for Retroareolar or Central Breast Cancers

PURPOSE: This study was conducted to evaluate the outcome of central lumpectomy for breast conservation including nipple-areolar resection and postoperative radiation therapy in patients with central breast cancers. METHODS: 19 patients with central breast cancers, aged 39 to 72 years, operated on from May 2004 to March 2010 were identified. Recurrence, survival, and cosmesis were analyzed. Treatment was undertaken as complete excision of the nipple-areolar complex (NAC), followed by external radiation to the whole breast and tumor bed. The mean follow-up period was 37.9 (1 to 71) months. RESULTS: At pathology, 13 had invasive ductal carcinoma; 5 had ductal carcinoma in situ. 1 had neuroendocrine cancer. Only 1 had atypical ductal hyperplasia at resection margin; the remaining 18 were free margins. The mean tumor size was 1.6 cm (range, 0.8~4 cm) and the distance from the nipple was 0~1 cm. 37.5% had positive axillary nodes. Adjuvant chemotherapy was given for 12 patients, followed by radiation therapy. All 15 patients, who were hormone receptor positive, were given tamoxifen or aromatase inhibitors. With a mean follow up of 37.9 months, all 19 patients are alive and free of disease. Cosmetic results ranged from good to excellent in 18 (94.7%) patients, as judged by both the patients and the surgeons. CONCLUSION: Although this study needs further evaluation and long-term follow up, subareolar or central breast cancers can be successfully treated with breast conserving therapy using nipple-areolar resection and postoperative radiation therapy, along with acceptable cosmesis.

The Surgical Management of Papillary Thyroid Microcarcinoma / 대한내분비외과학회지

PURPOSE: There has been a rapid rise in the incidence of thyroid cancer, particularly papillary thyroid microcarcinoma (PTMC). However, there is a lack of consensus of treatment guidelines or follow-up strategies. METHODS: A retrospective analysis of 606 patients who underwent operation due to thyroid cancer from March 2000 to December 2008 was conducted. Of these patients, 587 with pure papillary carcinomas were studied, of whom 392 (67%) presented with PTMC. RESULTS: Only 23% of patients were symptomatic, but 75% of patients were positive using the imaging techniques ultrasonography or positron emission tomography. When the microcarcinoma patient group (G1) was compared with the group of remaining patients (G2), less aggressive operations were chosen for G1. A lobectomy was performed in 63.8% of G1 versus in 14% of G2, and the central compartment neck dissection was omitted in 30% of G1 versus 16% of G2. During the follow-up period (mean 37.9±25.2 months), there were 11 recurrences. Two patients developed contralateral cancers 42 and 49 months after lobectomy. One patient had recurrences on central compartment lymph nodes 34 months post-operatively. Eight patients had lateral neck lymph nodes metastases 13~52 months postoperatively. Three of these eight patients had concomitant central neck lymph node metastases. CONCLUSION: Less aggressive treatments can be chosen for PTMC patients compared to non-PTMC patients. To clarify these results, longer follow up and larger and multi-institutional data are needed.

Breast Cancer Screening: A Medical Audit of the Screening Mammography Performed at One Institution for 10 Years / 한국유방암학회지

PURPOSE: Screening for breast cancer has constantly been increasing since the benefit of screening for breast cancers was established. The purpose of this study was to investigate the efficacy of annual breast cancer screening at one institution for 10 years by conducting a medical audit. METHODS: From March 1995 to July 2004, we performed 110,588 annual clinical examinations and mammographies on 58,024 women, who wanted to undergo breast cancer screening. Two hundred fourteen breast cancers were detected during screening, and one hundred sixty one of these patients were operated on. We then compared these results with the ideal rates for medical audits. RESULTS: Of the 110,588 cases that were screened, the recall rate for further examination was 12.1% (n=13,423). The biopsy rate was 1.01% (n=1,116). Two hundred fourteen breast cancers were detected for a detection rate of 0.19%. The percent of stage 0 cancer among all the cancer was 23.6%, stage I was 40.4%, stage IIa was 19.9%, stage IIb and IIIa were a combined 6.2%, stage IIIc was 3.1%, and stage IV was 0.6%. The positive predictive value (PPV) based on the abnormal findings on the screening examinations was 1.6% (PPV1). The PPV when a biopsy or surgical consultation was recommended was 15.1% (PPV2). The percent of tumor found as stage 0 or I was 64% (103/161). The tumor found as minimal cancer (stage 0 or tumor lesser than 1 cm) was 38.5% (62/161). There were 38 cases of axillary lymph node metastasis (23.6%). The number of cases of cancers found per 1,000 cases was 1.7. The prevalence of cancer found per 1,000 first examinations was 2.3. The incidental cancer found per 1,000 follow-up examinations was 1.2. The recall rate for further evaluation was 12.1%. These results were compatible with the ideal rates for medical audits, except for the recall rate, the PPV1, the PPV2, and the cancers found per 1,000 cases. CONCLUSION: On the base of these results, breast cancer screening was properly performed in this institution. Breast cancer screening using a clinical examination and a mammography is effective for the early detection of breast cancer.

Cancer Stem Cells / 한국유방암학회지

Recent results have supported the cancer stem cells hypothesis in which tumors originate from tissue stem cells or their early progenitors and, as a result, produce tumors that retain stem cell properties. These properties include selfrenewal that drives tumorigenesis and differentiation that contributes to cellular heterogeneity. The number of these cells is very small, and is tightly controlled by the self-renewal pathway and the signals of their environment (niche). Evidence for the existence of cancer stem cells has been reported for a number of human cancers including leukemia, cancers of the breast, brain, and colon. Although our understanding of the biology of these cancer stem cells remains rudimentary, the existence of these cells has implications for current conceptualization of malignant transformation and targeted therapy for the treatment of cancer.

Cancer Stem Cells / 한국유방암학회지

Recent results have supported the cancer stem cells hypothesis in which tumors originate from tissue stem cells or their early progenitors and, as a result, produce tumors that retain stem cell properties. These properties include selfrenewal that drives tumorigenesis and differentiation that contributes to cellular heterogeneity. The number of these cells is very small, and is tightly controlled by the self-renewal pathway and the signals of their environment (niche). Evidence for the existence of cancer stem cells has been reported for a number of human cancers including leukemia, cancers of the breast, brain, and colon. Although our understanding of the biology of these cancer stem cells remains rudimentary, the existence of these cells has implications for current conceptualization of malignant transformation and targeted therapy for the treatment of cancer.