Aesun Shin

Gastric Cancer Epidemiology in Korea

Gastric cancer has been the most commonly diagnosed cancer in Korea although the age-standardized mortality and incidence has decreased gradually during last two decades. Helicobacter pylori infection and cigarette smoking are well-established risk factors, and the role of dietary factors, such as salted foods, fresh vegetables and fruits, soy foods, and processed or grilled meats on gastric carcinogenesis has been suggested. In this review, we review national and international gastric cancer statistics, studies on environmental risk factors conducted in the Korean population, and gastric cancer screening activities.

Genome-wide association analyses in east Asians identify new susceptibility loci for colorectal cancer

To identify new genetic factors for colorectal cancer (CRC), we conducted a genome-wide association study in east Asians. By analyzing genome-wide data in 2,098 cases and 5,749 controls, we selected 64 promising SNPs for replication in an independent set of samples, including up to 5,358 cases and 5,922 controls. We identified four SNPs with association P values of 8.58 × 10−7 to 3.77 × 10−10 in the combined analysis of all east Asian samples. Three of the four were replicated in a study conducted in 26,060 individuals of European descent, with combined P values of 1.22 × 10−10 for rs647161 (5q31.1), 6.64 × 10−9 for rs2423279 (20p12.3) and 3.06 × 10−8 for rs10774214 (12p13.32 near the CCND2 gene), derived from meta-analysis of data from both east Asian and European-ancestry populations. This study identified three new CRC susceptibility loci and provides additional insight into the genetics and biology of CRC.

Large-scale genetic study in East Asians identifies six new loci associated with colorectal cancer risk

Known genetic loci explain only a small proportion of the familial relative risk of colorectal cancer (CRC). We conducted a genome-wide association study of CRC in East Asians with 14,963 cases and 31,945 controls and identified 6 new loci associated with CRC risk (P = 3.42 × 10−8 to 9.22 × 10−21) at 10q22.3, 10q25.2, 11q12.2, 12p13.31, 17p13.3 and 19q13.2. Two of these loci map to genes (TCF7L2 and TGFB1) with established roles in colorectal tumorigenesis. Four other loci are located in or near genes involved in transcriptional regulation (ZMIZ1), genome maintenance (FEN1), fatty acid metabolism (FADS1 and FADS2), cancer cell motility and metastasis (CD9), and cell growth and differentiation (NXN). We also found suggestive evidence for three additional loci associated with CRC risk near genome-wide significance at 8q24.11, 10q21.1 and 10q24.2. Furthermore, we replicated 22 previously reported CRC-associated loci. Our study provides insights into the genetic basis of CRC and suggests the involvement of new biological pathways.

Fatty fish and fish omega-3 fatty acid intakes decrease the breast cancer risk: a case-control study

BackgroundAlthough it is believed that fish ω-3 fatty acids may decrease breast cancer risk, epidemiological evidence has been inconclusive. This study examined the association between fish and fish ω-3 fatty acids intake with the risk of breast cancer in a case-control study of Korean women.MethodsWe recruited 358 incident breast cancer patients and 360 controls with no history of malignant neoplasm from the National Cancer Center Hospital between July 2007 and April 2008. The study participants were given a 103-item food intake frequency questionnaire to determine their dietary consumption of fish (fatty and lean fish) and ω-3 fatty acids derived from fish (eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA)).ResultsUsing a multivariate logistic regression model, high intake of fatty fish was associated with a reduced risk for breast cancer in both pre- and postmenopausal women (OR [95% CI] for highest vs. lowest intake quartiles, p for trend: 0.19 [0.08 to 0.45], p < 0.001 for premenopausal women, 0.27 [0.11 to 0.66], p = 0.005 for postmenopausal women). Similarly, reductions in breast cancer risk were observed among postmenopausal subjects who consumed more than 0.101 g of EPA (OR [95% CI]: 0.38 [0.15 to 0.96]) and 0.213 g of DHA (OR [95% CI]: 0.32 [0.13 to 0.82]) from fish per day compared to the reference group who consumed less than 0.014 g of EPA and 0.037 g of DHA per day. Among premenopausal women, there was a significant reduction in breast cancer risk for the highest intake quartiles of ω-3 fatty acids (ORs [95% CI]: 0.46 [0.22 to 0.96]), compared to the reference group who consumed the lowest quartile of intake.ConclusionThese results suggest that high consumption of fatty fish is associated with a reduced risk for breast cancer, and that the intake of ω-3 fatty acids from fish is inversely associated with postmenopausal breast cancer risk.

Estrogen receptor alpha gene polymorphisms and breast cancer risk

We conducted a hospital-based case-control study to evaluate the association between the XbaI and PvuII restriction fragment length polymorphisms (RFLPs) in intron 1 of the estrogen receptor α (ERα) gene and breast cancer risk. The study population consisted of 205 histologically confirmed incident breast cancer cases and 205 age-matched controls with no present and previous history of cancer. The PvuII genotype distribution did not show any difference between cases and controls, but the adjusted odds ratio (OR) for the XbaI X allele containing genotypes was 0.4 (95% CI: 0.3–0.6) compared with the xx genotype. The decrease in the OR appeared to be more attributable to the postmenopausal women; the ORs were 0.3 (95% CI: 0.1–0.5) and 0.5 (95% CI: 0.3–0.9) for postmenopausal and premenopausal women, respectively. Our results therefore suggest that the ERα XbaI polymorphism modifies individual susceptibility to breast cancer in Korean women.

Incidence of cervical, endometrial, and ovarian cancer in Korea, 1999-2010

Objective To investigate the recent incidence of and trends in cervical, endometrial, and ovarian cancer in Korean females. Methods Data from the Korea Central Cancer Registry between 1999 and 2010 were analyzed. Age-standardized rates (ASRs) and annual percent changes (APCs) were calculated. Results The absolute incidence rates of the three major gynecologic cancers increased: 6,394 in 1999 to 7,454 in 2010. The ASR for gynecologic cancer was 23.7 per 100,000 in 1999 and decreased to 21.0 in 2010 (APC, -1.1%; 95% confidence interval [CI], -1.53 to -0.70) due to a definitive decrease in the incidence of cervical cancer (APC, -4.3%). Endometrial cancer has been definitively increasing (APC, 6.9% during 1999-2010), especially in females <30 years old (APC, 11.2%) and in females ≥80 years old (APC, 9.5%). The incidence of ovarian cancer is increasing gradually (APC, 1.5%). Conclusion ASRs and APC for gynecologic cancers overall are decreasing due to the decrease in the incidence of cervical cancer. However, the incidence of endometrial and ovarian cancer has been increasing.

Genetic polymorphisms of cytochrome P450 19 and 1B1, alcohol use, and breast cancer risk in Korean women.

A case–control study was performed to assess the potential influence of CYP19 Arg264Cys and CYP1B1 Leu432Val polymorphisms on breast cancer risk in a series of Korean breast cancer patients and controls. The results suggest that the CYP19 Arg264Cys polymorphism modifies breast cancer risk (OR=1.5, 95% CI=1.1–2.2), especially in association with alcohol consumption (P for interaction=0.04), whereas the CYP1B1 Leu432Val polymorphism appears to play no role here.

Increasing Trend of Colorectal Cancer Incidence in Korea, 1999-2009

Purpose This study was conducted in order to demonstrate changing trends in colorectal cancer incidence according to sex, age group, and anatomical location in the Korean population. Materials and Methods Data from the Korea Central Cancer Registry between 1999 and 2009 were analyzed. Annual percent changes (APCs) of sex- and age-specific incidence rates for cancer of the proximal colon (International Statistical Classification of Diseases and Related Health Problems, 10th revision [ICD-10] code C18.0-18.5), distal colon (C18.6-18.7), and rectum (C19-20), and male-to-female incidence rate ratios (IRR) were calculated. Results The age-standardized incidence rate (ASR) of colorectal cancer was 27 (per 100,000) in 1999 and increased to 50.2 in 2009 among men (APC, 6.6%). The ASR for women was 17.2 in 1999 and 26.9 in 2009 (APC, 5.1%). The rectum was the most common site of cancer among both men and women during 1999 and 2009. However, the distal colon had the highest APC (10.8% among men and 8.4% among women), followed by the proximal colon (7.9% among men and 6.6% among women), and rectum (5.2% among men and 2.4% among women). The proportion of rectal cancer decreased from 51.5% in 1999 to 47.1% in 2009 among men, and from 50.5% to 42.8% among women. An increase in the male-to-female IRR was observed for distal colon cancer and rectal cancer, whereas the IRR for proximal colon cancer was stable. Conclusion The rapid increase in colorectal cancer incidence is mainly attributed to the increase in colon cancer, especially distal colon cancer, and may be explained by a transition of risk factors for subsites or by the effect of colorectal cancer screening.

Dietary Intake, Eating Habits, and Metabolic Syndrome in Korean Men

BACKGROUND Dietary factors contribute to the risk of developing metabolic syndrome, a disorder associated with an increased risk of developing cardiovascular disease, diabetes mellitus, and some cancers. OBJECTIVE The objective of this study was to evaluate the association between the intake frequencies of certain food groups, eating habits, and the risk of metabolic syndrome in a cross-sectional study of Korean men. METHODS Study participants were recruited from the National Cancer Center in South Korea. A total of 7,081 men aged 30 years and older were recruited between August 2002 and May 2007. Metabolic syndrome was defined as having three or more of the following conditions: obesity, high blood pressure, low high-density lipoprotein cholesterol level, high triglyceride level, and high fasting blood glucose level. The association of metabolic syndrome and sociodemographic characteristics, food intake frequencies, and eating habits assessed by a food frequency questionnaire, was examined. RESULTS The prevalence rate of metabolic syndrome for men aged 30 to 39, 40 to 49, 50 to 59, and 60+ years was 18.2%, 19.8%, 21.9%, and 20.5%, respectively. The study participants with metabolic syndrome had significantly higher family history of type 2 diabetes mellitus (27.6% vs 21.6%, P<0.001), and were more likely to be current smokers (50.1% vs 45.3%, P=0.005) than their counterparts. Among food group items, participants with metabolic syndrome showed significantly higher intake of seaweed (odds ratio [OR] 1.25, 95% confidence interval [CI] 1.05 to 1.50), and oily foods (OR 1.28, 95% CI 1.04 to 1.57) than participants without metabolic syndrome. In addition, the group with metabolic syndrome was more likely to eat quickly (OR 2.23, 95% CI 1.60 to 3.12 for fast vs slow) and to overeat frequently (OR 2.37, 95% CI 1.85 to 3.05 for more than 4 times a week vs less than once a week). CONCLUSIONS The results suggest that high intake of seaweed and oily foods as well as eating habits such as eating faster and frequent overeating, are associated with the risk of metabolic syndrome. In contrast, high fruit intake may be associated with a lower risk of metabolic syndrome. The importance of dietary habits in metabolic syndrome development needs to be pursued in further studies.

Genetic Polymorphisms of the Transforming Growth Factor-β1 Gene and Breast Cancer Risk: A Possible Dual Role at Different Cancer Stages

Transforming growth factor-β (TGF-β) inhibits the proliferation of carcinomas in early stages of breast cancer, whereas it promotes tumor growth and metastasis in later stages of cancer. We evaluated a possible association between TGF-β1 gene polymorphisms and breast cancer risk in a population-based case-control study of Chinese women living in Shanghai, which included 1,127 breast cancer cases and 1,228 population controls. Two polymorphisms, C-509T and T+29C, were in strong linkage disequilibrium. There were no overall differences in the genotype distribution of T+29C polymorphisms of the TGF-β1 gene among cases and controls. However, the distribution of the high-activity C allele of T+29C polymorphisms differed by cancer stages (Ptrend = 0.02). This allele was associated with decreased risk of early-stage breast cancer [stages 0 and I; odds ratio (OR), 0.73; 95% confidence interval (95% CI), 0.54-0.99], and the OR was further reduced to 0.66 (95% CI, 0.45-0.96) for those homozygous for this allele (Ptrend = 0.03). On the other hand, the same allele was associated with nonsignificantly increased risk of breast cancer with advanced stages III and IV (OR, 1.33; 95% CI, 0.81-2.18), which differed significantly from that observed for early-stage cancer (P = 0.04). This result suggests a possible dual effect of TGF-β1 shown by in vitro experiments and provides an explanation for some of the inconsistent findings from previous epidemiologic studies that did not evaluate this association by cancer stage.