Educational inequalities in cancer survival: a role for comorbidities and health behaviours?

AIM: To describe educational inequalities in cancer survival and to what extent these can be explained by comorbidity and health behaviours (smoking, physical activity and alcohol consumption). METHODS: The GLOBE study sent postal questionnaires to individuals in The Netherlands in 1991 resulting in 18 973 respondents (response 70%). Questions were asked on education, health and health-related behaviours. Participants were linked for cancer diagnosis (1991-2008), comorbidity and survival (up to 2010) with the population-based Eindhoven Cancer Registry; 1127 tumours were included in the analyses. RESULTS: 5-year crude survival was best in highly educated patients as compared with low educated patients for all cancers combined: 49% versus 32% in male subjects (log rank: p<0.0001), 65% versus 49% in female subjects (p=0.0001). Compared with highly educated, low educated prostate cancer patients had an increased risk of death (HR 2.9 (95% CI 1.7 to 5.1), adjusted for age, stage and year). No or inconsistent associations between educational level and risk of death were seen in multivariable analyses for breast, colon and non-small cell lung cancer. Although survival in prostate cancer patients was affected by comorbidities (HR2_vs_0_comorbidities: 2.6 (1.5 to 4.4)), physical activity (HRno/little_vs__moderate_physical__activity: 2.0 (1.2 to 3.4)) and smoking (HRcurrent_vs_never_smokers: 2.6 (1.0-6.8)), these did not contribute to educational inequalities in prostate cancer survival (HRlow_vs_high_education: 3.1 (1.6 to 5.8) with adjustment for comorbidity and lifestyle). CONCLUSIONS: Compared with low educated, highly educated prostate cancer patients had better survival. Although presence of comorbidities, physical activity levels and smoking status affected survival from prostate cancer, these did not contribute to educational inequalities in survival. The role of other factors for inequalities in cancer survival needs to be explored.

Increasing incidence and decreasing mortality of colorectal cancer due to marked cohort effects in southern Netherlands.

In preparation for any type of forthcoming colorectal cancer (CRC) mass screening we examined trends in CRC incidence and mortality according to sex, subsite and age in southern Netherlands. Population-based data from the Eindhoven Cancer Registry during the period 1975-2004 were used. Age-period-cohort analyses were performed to investigate possible aetiologic, diagnostic or therapeutic origins of the trends. Age-adjusted (European Standardized Rates) incidence rates for colon cancer increased since 1975 from 23 in 100 000 for both sexes to about 38 in 100 000 for males and 30 in 100 000 for females in 2004. Incidence of rectal cancer remained relatively stable at about 25 in 100 000 males and 15 in 100 000 females. The incidence of CRC increased for male patients from birth cohorts between 1900 and 1955 (P=0.010), especially in left-sided colon cancer in the younger birth cohorts [RR1900: 0.8 (95% confidence interval, CI: 0.6, 1.0), RR1960: 1.6 (95% CI: 0.9, 2.8), reference: 1910-1919]. For women a similar, although weaker increase in CRC incidence was found. Mortality rates for CRC started to decrease in 1975, more pronounced for rectal than for colon cancer. The relative risk for dying in men with CRC decreased from 1.3 (95% CI: 1.0, 1.6) in the 1900 birth cohort to 0.1 (95% CI: 0.1, 0.4) in the 1960 birth cohort, reference 1910-1919 birth cohort. The increasing incidence and decreasing mortality in CRC is largely affected by birth cohort effects. Changes in CRC incidence are likely to be attributed to lifestyle factors and decreasing mortality is due to earlier detection and improved treatment, especially among younger patients.

Risk of new primary nonbreast cancers after breast cancer treatment: a Dutch population-based study.

PURPOSE: To assess the risk of secondary nonbreast cancers (SNBCs) in a recently treated population-based cohort of breast cancer patients focused on the association with treatment and prognostic implications. PATIENTS AND METHODS: In 58,068 Dutch patients diagnosed with invasive breast cancer between 1989 and 2003, SNBC risk was quantified using standardized incidence ratios (SIRs), cumulative incidence, and Cox regression analysis, adjusted for competing risks. RESULTS: After a median follow-up of 5.4 years, 2,578 SNBCs had occurred. Compared with the Dutch female population at large, in this cohort, the SIR of SNBCs was increased (SIR, 1.22; 95% CI, 1.17 to 1.27). The absolute excess risk was 13.6 (95% CI, 9.7 to 17.6) per 10,000 person-years. SIRs were elevated for cancers of the esophagus, stomach, colon, rectum, lung, uterus, ovary, kidney, and bladder cancers, and for soft tissue sarcomas (STS), melanoma, non-Hodgkin's lymphoma, and acute myeloid leukemia (AML). The 10-year cumulative incidence of SNBCs was 5.4% (95% CI, 5.1% to 5.7%). Among patients younger than 50 years, radiotherapy was associated with an increased lung cancer risk (hazard ratio [HR] = 2.31; 95% CI, 1.15 to 4.60) and chemotherapy with decreased risk for all SNBCs (HR = 0.78; 95% CI, 0.63 to 0.98) and for colon and lung cancer. Among patients age 50 years and older, radiotherapy was associated with raised STS risk (HR = 3.43; 95% CI, 1.46 to 8.04); chemotherapy with increased risks of melanoma, uterine cancer, and AML; and hormonal therapy with all SNBCs combined (HR = 1.10; 95% CI, 1.01 to 1.21) and uterine cancer (HR = 1.78; 95% CI, 1.40 to 2.27). An SNBC worsened survival (HR = 3.98; 95%CI 3.77 to 4.20). CONCLUSION: Breast cancer patients diagnosed in the 1990 s experienced a small but significant excess risk of developing an SNBC.

Trends in the prognosis of patients with primary metastatic breast cancer diagnosed between 1975 and 2002.

We performed a population-based study, including 1089 patients with primary metastatic breast cancer, diagnosed in South-East Netherlands between 1975 and 2002, and tried to give an answer to the question if prognosis of this patient group has improved or not. Follow-up was completed until 1 January 2005. The median survival times for patients with primary metastatic disease were 18, 17 and 20.5 months for patients diagnosed in the periods 1975-1984, 1985-1994 and 1995-2002, respectively. A multivariate analysis, including age, tumour size and information on the localization of metastatic disease and the number of metastatic sites, showed that patients diagnosed in the period 1995-2002 had a 18% lower death risk (95% confidence interval 5-30) compared to those diagnosed in the period 1985-1994. These data show that the prognosis of patients with primary metastatic breast cancer remained unchanged between 1975 and 1994 and that some progress has been made after 1994.

Investigating explanations of socio-economic inequalities in health: the Dutch GLOBE study.

BACKGROUND: The GLOBE study is a prospective cohort study specifically aimed at the explanation of socio-economic inequalities in health in the Netherlands. The returns of the study are reviewed after ten years of follow-up, and the studies' contribution to the development of policy measures to reduce inequalities in health in the Netherlands are described. METHODS: The study started in 1991 with a baseline postal survey (response rate 70.1% or n=18973, 15-74 years of age). Two sub-samples of respondents to this survey were subsequently interviewed in 1991 (response 79.4% and 72.3%, n=5667). Baseline data collection included measures of socio-economic position, health and possible explanatory factors. Follow-up involved repeated postal surveys and interviews, and routinely collected data on hospital admissions, cancer incidence and mortality by cause of death. RESULTS: Compared with higher socio-economic groups, lower socio-economic groups showed higher prevalence rates of poor self-reported health (perceived general health, health complaints, chronic conditions, disabilities), higher incidence rates of specific conditions (myocardial infarction) and higher rates of all-cause mortality. The higher prevalence of adverse material circumstances, unhealthy behaviour, adverse psychosocial characteristics, and adverse childhood circumstances in the lower socio-economic groups was important in the explanation of socio-economic inequalities in health. Socio-economic differences in health care utilization did not contribute to the explanation. CONCLUSIONS: The GLOBE study contributed significantly to the understanding of the explanation of socio-economic inequalities in health in the Netherlands. Study results were a main source of information in the development of policy measures aimed at the reduction of socio-economic inequalities in health in the Netherlands.