The association between cancer incidence and family income: analysis of Korean National Health Insurance cancer registration data

Impact of Small Area Level Deprivation on Colorectal Cancer Survival: Findings from the Regional Cancer Registry in Korea

BACKGROUND/OBJECTIVES

Research on the relationship between small-area-level deprivation and cancer survival, particularly for colorectal cancer (CRC), is lacking. Therefore, we investigated the relationship among small area-level deprivation, individual-level factors, and CRC survival using data from the Busan Regional Cancer Registry.

METHODS

We analyzed 34,999 patients with CRC from the Busan Regional Cancer Registry from 2003 to 2020. The primary outcome was CRC mortality. The explanatory variables at the individual level included age, gender, cancer stage, and year of diagnosis, whereas the Deprivation Index (DI) was used at the regional level. We conducted a multilevel survival analysis with frailty to assess the impact of individual- and area-level factors on survival probabilities.

RESULTS

In the multilevel survival model, each unit increase in the DI at the area level was associated with a 6.6% decrease in survival probability. When applying Model 2 and deriving regional estimates using the empirical Bayesian estimation method, the graph of the DI (x-axis) against survival probability (y-axis) showed that the slope of the regional DI for the 3-year and 5-year survival probabilities increased compared with the 1-year rate across all stages of the disease. Additionally, the slopes were steeper for the distant stage than for the local or regional stages.

CONCLUSIONS

Small-area level deprivation negatively affects CRC survival, especially in distant-stage patients and those with longer disease duration.

Income Dynamics and Risk of Colorectal Cancer in Individuals With Type 2 Diabetes: A Nationwide Population-based Cohort Study

BACKGROUND

Individuals with type 2 diabetes mellitus (T2DM) have increased colorectal cancer (CRC) risk, but it is unknown whether income dynamics are associated with CRC risk in these individuals. We examined whether persistent low- or high-income and income changes are associated with CRC risk in non-elderly adults with T2DM.

METHODS

Using nationally representative data from the Korean Health Insurance Service database, 1,909,492 adults aged 30 to 64 years with T2DM and no history of cancer were included between 2009 and 2012 (median follow-up of 7.8 years). We determined income levels based on health insurance premiums and assessed annual income quartiles for the baseline year and the four preceding years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated after adjusting for sociodemographic factors, CRC risk factors, and diabetes duration and treatment.

RESULTS

Persistent low income (ie, lowest income quartile) was associated with increased CRC risk (HR5 years vs 0 years 1.11; 95% CI, 1.04-1.18; P for trend = 0.004). Income declines (ie, a decrease ≥25% in income quantile) were also associated with increased CRC risk (HR≥2 vs 0 declines 1.10; 95% CI, 1.05-1.16; P for trend = 0.001). In contrast, persistent high income (ie, highest income quartile) was associated with decreased CRC risk (HR5 years vs 0 years 0.81; 95% CI, 0.73-0.89; P for trend < 0.0001), which was more pronounced for rectal cancer (HR 0.64; 95% CI, 0.53-0.78) and distal colon cancer (HR 0.70; 95% CI, 0.57-0.86).

CONCLUSION

Our findings underscore the need for increased public policy awareness of the association between income dynamics and CRC risk in adults with T2DM.

Disparities in Cancer Incidence across Income Levels in South Korea

BACKGROUND

Recent nationwide studies of disparities in cancer incidence by income are scarce in Korea. This study investigated such disparities in cancer incidence and the stage at cancer diagnosis across income groups in Korea.

METHODS

This study utilized data from a national cancer database, specifically focusing on cases recorded in the year 2018. Income levels were categorized into quintiles according to the insurance premium paid in addition to the Medicaid benefit. The slope index of inequality (SII) and relative index of inequality (RII) were used to measure absolute and relative differences in cancer incidence by income. A multivariable logistic regression was performed to estimate the risk of a distant stage at cancer diagnosis.

RESULTS

The total number of cases of incident cancer was 223,371 (men: 116,320, women: 107,051) with shares of the total of 29.5% (5Q), 20.4% (4Q), 16.0% (3Q), 13.5% (2Q), 15.6% (1Q), and 5% (Medicaid). The most common cancer type was thyroid cancer, followed by gastric and colorectal cancers. The age-standardized incidence rate for all cancers was lowest in the highest income group, but the SII was not statistically significant (SII: -35.7), and the RII was -0.07. Colorectal and cervical cancers had lower incidence rates for higher income groups, while thyroid and prostate cancers had higher incidence rates for higher income groups. The odds ratio for a distant stage at diagnosis for all cancers increased for lower income groups relative to 5Q.

CONCLUSIONS

Disparities in cancer incidence in a Korean population differed by cancer type, and lower income was a significant predictor of a distant stage at diagnosis for cancers overall. These results emphasize the need for further study of the underlying causes of disparities in cancer incidence and the stage at diagnosis, as well as the need for interventions to mitigate these disparities.

Individual and joint effect of socioeconomic status and lifestyle factors on cancer in Korea

BACKGROUND

There is limited evidence on the individual and joint effect of socioeconomic status (SES) and unhealthy lifestyle on cancer. Therefore, this study aimed to examine the effects of these factors on cancer incidence and mortality.

METHODS

In this population-based cohort study, income was used as the proxy of SES. A combined unhealthy lifestyle score was obtained using data on smoking, alcohol consumption, physical activity, and body mass index. Hazard ratios were estimated using a Cox proportional hazards model.

RESULTS

The study included data on 8,353,169 participants (median follow-up period, 17 years). Although the association between low income and cancer incidence varied depending on cancer type, low income consistently increased the risk of cancer-related death with a social gradient. Unhealthy behaviors increased the risk of cancer incidence and mortality, except for thyroid and breast cancer in women and prostate cancer in men. Compared with the wealthiest and healthiest individuals, the poorest and unhealthiest men and women showed 2.1-fold (2.05-2.14) and 1.36-fold (1.31-1.41) higher risk of cancer-related death, respectively. The joint effect was most robust for lung, liver, head, and neck cancers in men and liver and cervical cancers in women; further, the effect was stronger with cancer-specific mortality than with incidence.

CONCLUSION

In conclusion, income and combined healthy lifestyle behaviors have individual and joint effects on cancer incidence and mortality. The effect varies by cancer type and sex.

Inequality in Life Expectancy in Korea according to Various Categorizations of the National Health Insurance Premiums as a Marker of Income

The purpose of this study was to examine the degree to which the magnitude of income inequality in life expectancy according to different categorization across beneficiary types under the National Health Insurance Service (NHIS) in Korea. We used population and death data in 2017 from the National Health Information Database of the NHIS. Income quintile groups were classified in four ways according to beneficiary type (employee insured, self-employed insured, and Medical Aid beneficiaries). Standard life table procedures were used to calculate life expectancy. The life expectancy gap between the lowest and highest income quintiles was the largest when the entire population was divided into quintiles without distinguishing among types of beneficiaries. In conclusion, we suggest that income quintile indicators in NHIS data, measured without distinguishing among types of beneficiaries, may best represent the magnitude of health inequalities in Korean society. This indicator could be used for future research on health inequalities, as well as for monitoring health inequalities in Korea.

Socioeconomic Status in Relation to Risks of Major Gastrointestinal Cancers in Chinese Adults: A Prospective Study of 0.5 Million People

BACKGROUND

Low socioeconomic status (SES) is associated with higher risk of certain gastrointestinal (e.g., colorectal, pancreatic, and liver) cancers in Western populations. Evidence is very limited in China, where correlates and determinants of SES differ from those in the West.

METHODS

The prospective China Kadoorie Biobank recruited 512,715 adults (59% women, mean age 51 years) from 10 (5 urban, 5 rural) regions. During 10 years of follow-up, 27,940 incident cancers (including 3,061 colorectal, 805 pancreatic, and 2,904 liver) were recorded among 510,131 participants without prior cancer at baseline. Cox regression was used to estimate adjusted HRs for specific cancers associated with area-level (e.g., per capita gross domestic product, disposable income) and individual-level (e.g., education, household income) SES.

RESULTS

Area-level SES and household income showed positive associations with incident colorectal and pancreatic cancers and inverse associations with liver cancer (P _trend < 0.05). Education showed no association with colorectal cancer but inverse associations with pancreatic and liver cancers, with adjusted HRs comparing university to no formal schooling being 1.05 [95% confidence interval (CI), 0.85-1.29], 0.49 (95% CI, 0.28-0.85), and 0.61 (95% CI, 0.47-0.81), respectively. Potential risk factors (e.g., smoking, alcohol) partly explained the inverse associations of education with pancreatic and liver cancers (17.6% and 60.4%), respectively.

CONCLUSIONS

Among Chinese adults, the associations of SES with gastrointestinal cancers differed by cancer type and SES indicator. Potential risk factors partially explained the inverse associations of education with pancreatic and liver cancers.

IMPACT

The different associations between SES with gastrointestinal cancers may inform cancer prevention strategies.

Relationship between Socioeconomic Status and Prevalent Prostate Cancer in the South Korea

BACKGROUND

Prostate cancer prevalence recently has increased among male adults in South Korea. But, few study has evaluated the reason. Therefore, we investigated the relationship between socioeconomic status and prevalent prostate cancer.

METHODS

This study enrolled 16,215 males aged 40 years and over who took part in the Korean National Health and Nutrition Examination Survey 2007-2016. In addition, we obtained the 2000-2016 age-standardized incidence rate and age-standardized mortality rate of prostate cancer from the Korean Statistical Information Service.

RESULTS

After adjusting for other covariates, prevalent prostate cancer was significantly associated with monthly household income (OR 3.71, 95% confidence interval [CI] 1.48-9.30, for highest vs. lowest) and significantly associated with education level (OR 3.66, 95% CI 1.54-8.70, for ≥ 13 vs. ≤ 6). In the analysis of the age-standardized incidence rate and the age-standardized mortality rate, the age-standardized incidence rate has soared from 2000 to 2011 and then decreased gradually, but the age-standardized mortality rate did not change.

CONCLUSION

In our results, prevalent prostate cancer increased significantly with socioeconomic status and the increase in prevalent prostate cancer may be attributable to earlier detection rather than to a real increase in prevalence.

Determinants of undergoing thyroid cancer screening in Korean women: a cross-sectional analysis from the K-Stori 2016

OBJECTIVES

Thyroid cancer is the most common cancer among Korean women. Studies suggest that the incidence of thyroid cancer might be associated with overdiagnosis resulting from thyroid cancer screening. The objective of this study was to identify the determinants of participation in thyroid cancer screening in Korean women.

METHODS

Data were obtained from the 2016 Korean Study of Women's Health-Related Issues, a nationwide cross-sectional survey of women according to the reproductive life cycle. A total of 8697 cancer-free women of ages between 20 and 79 years were included for analysis. Multivariable logistic regression analysis was applied to analyse factors associated with adherence to thyroid cancer screening based on Andersen's health behavioural model.

RESULTS

Over the last 2 years, the rate of thyroid cancer screening was 39.2%. In multivariable models, older age, higher household income, high school education level and higher perceived risk of cancer were positively associated with thyroid cancer screening participation. Moreover, women who underwent cervical cancer screening (adjusted OR [aOR] 3.67; 95% CI 2.90 to 4.64) and breast cancer screening (aOR 10.91; 95% CI 8.41 to 14.14) had higher odds of attending thyroid cancer screening than women who did not attend cancer screening.

CONCLUSIONS

These findings highlight the need to increase awareness of different recommendations on screening for various cancers to improve cost-effectiveness and to prevent unnecessary treatments.

Recurrent aphthous stomatitis may be a precursor or risk factor for specific cancers: A case-control frequency-matched study

BACKGROUND

Recurrent aphthous stomatitis (RAS) is considered a prophase symptom in patients with specific cancers. This study assessed the association between RAS and subsequent onset of cancer based on a nationwide population-based database in Taiwan.

MATERIALS AND METHODS

We selected study participants from the National Health Insurance Research Database from January 2000 to December 2008. Patients in the non-RAS cohort were matched to case study patients at a 1:1 ratio through frequency matching. All participants were followed up for at least 5 years, and those who received cancer diagnoses during follow-up were identified.

RESULTS

Among 52 307 patients with and 52 304 patients without RAS, the combined hazard ratio (HR) of all subsequent cancer cases was 1.3 (95% confidence interval [CI]: 1.25-1.35, P = 0). RAS diagnosis was associated with risk for cancers of the head and neck (aHR = 2, 95% CI: 1.8-2.3), colon (aHR = 1.2, 95% CI: 1.1-1.4), liver (aHR = 1.1, 95% CI: 1-1.3), pancreas (aHR = 1.4, 95% CI: 1.1-1.7), skin (aHR = 1.4, 95% CI: 1.2-1.7), breast (aHR = 1.2, 95% CI: 1.1-1.4), and prostate (aHR = 1.5, 95% CI: 1.3-1.8), as well as hematologic cancers (aHR = 1.6, 95% CI: 1.3-1.9). A higher risk was observed for male patients (aHR = 1.35, 95% CI: 1.28-1.42) than for female patients (aHR = 1.25, 95% CI: 1.18-1.31) with RAS.

CONCLUSIONS

RAS was associated with specific cancers. Susceptible RAS patients should be screened for specific cancers.

Higher breast cancer prevalence associated with higher socioeconomic status in the South Korean population; Has it resulted from overdiagnosis?

Recently, breast cancer prevalence has increased in South Korea. In this study, we investigated the correlation between breast cancer prevalence and socioeconomic status. This study enrolled 27,331 people who participated in the Korean National Health and Nutrition Examination Survey (KNHANES) IV–VI (2007–2015). In addition, we obtained data from the Korean Statistical Information Service (KSIS) on the breast cancer age-standardized incidence rate (AIR), the age-standardized mortality rate (AMR), the number of women screened, and the number of newly diagnosed patients. The KHANES data showed that breast cancer prevalence was significantly associated with educational level (odds ratio [OR], 2.02; 95% confidence interval [CI], 1.08–3.77 for 10–12 vs. ≤ 6 years of education, and OR, 2.36; 95% CI, 1.10–5.06 for ≥ 13 vs. ≤ 6 years of education). However, there was no significant association of breast cancer prevalence with monthly household income. In a separate analysis of the AIR, AMR, and number of women screened for breast cancer, the AIR increased with the number of women screened, whereas the AMR did not. Furthermore, the number of newly diagnosed patients in all age groups increased over time. The present results demonstrate that the recently increased breast cancer prevalence documented in South Korea may be attributable to earlier detection rather than to a real increase in prevalence, and that breast cancer may be overdiagnosed.

Temporal trends in educational inequalities in non-communicable diseases in Korea, 2007-2015

Background

Socioeconomic inequalities in non-communicable diseases are known to exist; however there is a paucity of research describing the secular trends in these inequalities. To this end, the current study aims to explore the recent time trends in social patterning of selected non-communicable diseases among Korean adults between 2007 and 2015.

Methods

Using data from the Korea National Health and Nutrition Examination Survey (KNHANES), temporal trends in socioeconomic inequalities in diabetes, arthritis, asthma and depressive symptoms were assessed across three time points. Respondents were adults aged 20 years or over (N = 47,091, 20,180 men and 26,911 women). Socioeconomic circumstance was assessed based on highest level of educational attainment. We estimated prevalence ratios with 95% confidence intervals using Poisson regression with robust variance estimation (adjusted for age, smoking status, alcohol consumption, obesity, and physical activity) separately for men and women. The magnitude of the inequalities was computed using the relative index of inequality (RII).

Results

In men, diabetes was not associated with educational attainment, while there was evidence of a negative association in women across surveys. Similar inverse associations were found with arthritis and depressive symptoms, but these associations were less clear for asthma. RII showed a non-significant increasing trend in educational disparities in depressive symptoms. Meanwhile, relative inequalities in diabetes, arthritis and asthma have narrowed. These trends were, in general, more pronounced in women.

Conclusions

The findings of this study indicate higher burden of selected NCDs among the lower educational groups, particularly among women. In addition, our results indicated some improvements in inequalities in diabetes, arthritis and asthma in recent years. These findings have important implications for understanding the causes of social patterning of NCDs and for the targeting of effective interventions.

Growing incidence of thyroid carcinoma in recent years: Factors underlying overdiagnosis

There is an increasing incidence of well-differentiated thyroid cancer worldwide. Much of the increase is secondary to increased detection of small, low-risk tumors, with questionable clinical significance. This review addresses the factors that contribute to the increasing incidence and considers environmental, and patient-based and clinician-led influences. Articles addressing the causes of the increased incidence were critically reviewed. A complex interplay of environmental, medical, and social pressures has resulted in increased awareness of the thyroid disease risk, increased screening of thyroid cancers, and increased diagnosis of thyroid cancers. Although there is evidence to suggest that the true disease incidence may be changing slightly, most of the increase is related to factors that promote early diagnosis of low-risk lesions, which is resulting in a significant phenomenon of overdiagnosis. An improved understanding of these pressures at a global level will enable healthcare policymakers to react appropriately to this challenge in the future.

Joint Symposium of Korean Cancer Association & UICC-ARO-Cross-boundary cancer studies: cancer and Universal Health Coverage (UHC) in Asia

On 16 June 2016, the Korean Cancer Association (KCA) and Union for International Cancer Control-Asia Regional Office (UICC-ARO) organized a joint symposium as part of the official program of the 42nd Annual Meeting of the Korean Cancer Association to discuss the topic 'Cross-boundary Cancer Studies: Cancer and Universal Health Coverage (UHC) in Asia.' Universal Health Coverage is included in the Sustainable Development Goals adopted by the United Nations as part of the 2030 Agenda for Sustainable Development. The objectives of UHC are to ensure that all people can receive high-quality medical services, are protected from public health risks, and are prevented from falling into poverty due to medical costs or loss of income arising from illness. The participants discussed the growing cost of cancer in the Asian region and the challenges that this poses to the establishment and deployment of UHC in the countries of Asia, all of which face budgetary and other systemic constraints in controlling cancer in the region. Representatives from Korea, Japan and Indonesia reported on the status of UHC in their countries and the challenges that are being faced, many of which are common to other countries in Asia. In addition to country-specific presentations about the progress of and challenges facing UHC, there were also presentations from WHO Kobe Centre concerning advancing UHC in non-communicable diseases and prospects for further collaboration and research on UHC. A presentation from the University of Tokyo also highlighted the need to focus on multidisciplinary studies in an age of globalization and digitization.

Inequality in mortality by occupation related to economic crisis from 1980 to 2010 among working-age Japanese males

The mortality rate for Japanese males aged 30–59 years in managerial and professional spiked in 2000 and remains worse than that of other occupations possibly associated with the economic downturn of the 1990s and the global economic stagnation after 2008. The present study aimed to assess temporal occupation-specific mortality trends from 1980 to 2010 for Japanese males aged 30–59 years for major causes of death. We obtained data from the Occupation-specific Vital Statistics. We calculated age-standardized mortality rates for the four leading causes of death (all cancers, suicide, ischaemic heart disease, and cerebrovascular disease). We used a generalized estimating equation model to determine specific effects of the economic downturn after 2000. The age-standardized mortality rate for the total working-age population steadily declined up to 2010 in all major causes of death except suicide. Managers had a higher risk of mortality in all leading causes of death compared with before 1995. Mortality rates among unemployed people steadily decreased for all cancers and ischaemic heart disease. Economic downturn may have caused the prolonged increase in suicide mortality. Unemployed people did not experience any change in mortality due to suicide and cerebrovascular disease and saw a decline in cancer and ischemic heart disease mortality, perhaps because the basic properties of Japan’s social welfare system were maintained even during economic recession.

Cancer Incidence in Physicians: A Taiwan National Population-based Cohort Study

Cancer has been the leading cause of death in Taiwan since 1982. Physicians have many health-related risk factors which may contribute to cancer, such as rotating night shift, radiation, poor lifestyle, and higher exposure risk to infection and potential carcinogenic drugs. However, the cancer risk in physicians is not clear. In Taiwan's National Health Insurance Research Database, we identified 14,889 physicians as the study cohort and randomly selected 29,778 nonmedical staff patients as the comparison cohort for this national population-based cohort study. Cox proportional-hazard regression was used to compare the cancer risk between physicians and comparisons. Physician subgroups were also analyzed. Physicians had a lower all-cancer risk than did the comparisons (hazard ratio [HR] 0.86, 95% confidence interval [CI] 0.76-0.97). In the sex-based analysis, male physicians had a lower all-cancer risk than did male comparisons (HR 0.82, 95% CI 0.73-0.94); and female physicians did not (HR 1.29, 95% CI 0.88-1.91). In the cancer-type analysis, male physicians had a higher risk of prostate cancer (HR 1.72, 95% CI 1.12-2.65) and female physicians had twice the risk of breast cancer (HR 2.00, 95% CI 1.11-3.62) than did comparisons. Cancer risk was not significantly associated with physician specialties. Physicians in Taiwan had a lower all-cancer risk but higher risks for prostate and breast cancer than did the general population. These new epidemiological findings require additional study to clarify possible mechanisms.

Age of diagnosing physician impacts the incidence of thyroid cancer in a population

BACKGROUND

Thyroid ultrasound and fine-needle aspiration (FNA) have been implicated in the overdiagnosis of thyroid cancer. To study how the use of diagnostic tools impacts thyroid cancer incidence, we propose using physician age as a surrogate. We aimed to determine whether thyroid cancer incidence is higher in areas with a high density of young physicians compared with areas with a high density of older physicians.

METHODS

SEER 13 database was used to determine thyroid cancer incidence. These data were linked to the Area Resource File data (2000), containing information on physician age at a county-specific level. Cohorts were divided by age based on the concentration of physicians within a population of 1,000,000 persons. The study period was divided into two time periods (1992-1995, 2006-2009).

RESULTS

The incidence of thyroid cancer was stable in areas with high concentrations of young and older physicians during the 1992-1995 time period [<35: 5.97; 55-64: 6.82; ≥65: 6.70 (per 100,000py)]. Areas with high concentrations of young physicians had an increased incidence of thyroid cancer compared with areas of high concentrations of older physicians during the 2006-2009 period [<35: 13.3; 55-64: 9.86; ≥65: 7.47 (per 100,000py)].

CONCLUSIONS

Thyroid cancer incidence was lower in areas with high concentrations of older physicians. This may be the result of increased adoption of thyroid ultrasound and FNA among younger physicians who have trained after diagnostic tools became common. Age of the diagnosing physician is a surrogate for diagnostic utility contributing to thyroid cancer trends.

Expression of heat shock protein 27 in prostate cancer cell lines according to the extent of malignancy and doxazosin treatment

Purpose

Heat shock protein 27 (HSP27) is known as the material that plays a role in apoptosis control in tumor and cell protection including the immune response, drug tolerance, and so on. In this study, HSP27 expression according to the prostate cancer malignancy level was evaluated, and HSP27 expression was also analyzed after inducing apoptosis by doxazosin treatment of the prostate cancer cell lines.

Materials and Methods

Reverse transcription polymerase chain reaction (RT-PCR) and immunofluorescence staining of the HSP27 was implemented by the culture of RWPE-1, LNCaP, androgen-independent human prostate cancer cells (PC-3), and TSU-Pr1 cell lines. Analysis was separately conducted in the control group, control vector group treated by dimethyl sulfoxide, and groups treated with 10 µM or 25 µM doxazosin. The expression of HSP27 in RT-PCR and immunofluorescence staining was observed and evaluated after conversion to numerical values.

Results

In the RT-PCR results, depending on the cell type, LNCaP, TSU-Pr1 showed the highest HSP27 expression followed by PC-3, LNCaP and RWPE-1 in sequence. After doxazosin treatment, the expression detected by RT-PCR was stronger at a 25-µM doxazosin concentration compared to that at a 10-µM concentration, and the result was similar by immunofluorescence staining.

Conclusions

HSP27 expression increased depending on the prostate cancer cell line. This meant that HSP27 expression was related to the prostate cancer malignancy level. Additionally, the higher the treatment concentration in PC-3 was, the higher the HSP27 expression was. This result showed that doxazosin induced apoptosis of prostate cancer.

The association between the socioeconomic status and thyroid cancer prevalence; based on the Korean National Health and Nutrition Examination Survey 2010-2011

The incidence of thyroid cancer has recently increased in most industrialized countries, including Korea. To date, few studies have examined the association between thyroid cancer and socioeconomic status (SES). The current study was based on data collected from a total of 12,276 subjects (5,277 men and 6,999 women) by the Korean National Health and Nutrition Examination Survey (KNHANES) between 2010 and 2011. Univariate and multivariate logistic regression analysis revealed that older age (odds ration [OR], 1.03; 95% confidence interval [CI], 1.00-1.05), being female (OR, 8.16; 95%CI, 2.99-22.24), being overweight (OR, 1.04; 95%CI, 1.01-1.06), monthly household income (OR, 3.27; 95%CI, 1.16-9.20 for medium-highest household income vs lowest household income; OR, 3.30; 95%CI, 1.16-9.34 for highest household income vs lowest household income), educational level (OR, 2.74; 95%CI, 1.16-6.46 for 10-12 yr vs < 7 yr) and alcohol consumption (OR, 1.89; 95%CI 1.08-3.32) were significant risk factors for thyroid cancer. Our results indicate that the recent increase in thyroid cancer is attributable to better early detection rather than to any increase in actual prevalence.

Risk factors for double primary malignancies and their clinical implications in patients with sporadic gastric cancer

AIMS

We carried out a large scale study to identify the risk factors for double primary malignancy (DPM) development in gastric cancer patients and to evaluate the clinical implications for these patients.

METHODS

A total of 2593 patients who underwent gastrectomy for primary gastric cancer from January 2005 to November 2010 were reviewed with regard to DPM. We compared the clinicopathological characteristics, risk factors for developing DPM, and prognosis between the DPM+ group and the DPM- group.

RESULTS

Of the 2593 patients, 152 (5.9%) were diagnosed with DPM. The most common accompanying malignancies were colorectal, lung and thyroid. Multivariate analysis indicated that age (p = 0.016) and MSI status (p = 0.002) were associated with a higher frequency of DPM. 30.3% of patients were diagnosed with DPM within 1 year around perioperative period and 53.3% of patients had DPM detected during 5 years of post-operative follow up periods. Although there was no significant difference in overall survival between the DPM+ and DPM- group, DPM+ patients had a worse prognosis than DPM- patients in stage I gastric cancer.

CONCLUSIONS

Gastric cancer patients over the age of 60 or with a MSI-high status had an increased risk for developing DPM. Further, in stage I gastric cancer, the presence of DPM was associated with a worse prognosis. Therefore, careful pre- and postoperative surveillance is especially important in these patients.