Breast cancer and occupation: Non-parametric and parametric net survival analyses among Swiss women (1990-2014).

Introduction: Occupation can contribute to differences in risk and stage at diagnosis of breast cancer. This study aimed at determining whether occupation, along with skill level and the socio-professional category, affect the breast cancer survival (BCS) up to 10 years after diagnosis. Materials and methods: We used cancer registry records to identify women diagnosed with primary invasive breast cancer in western Switzerland over the period 1990-2014 and matched them with the Swiss National Cohort. The effect of work-related variables on BCS was assessed using non-parametric and parametric net survival methods. Results: Study sample included 8,678 women. In the non-parametric analysis, we observed a statistically significant effect of all work-related variables on BCS. Women in elementary occupations, with low skill level, and in paid employment not classified elsewhere, had the lowest BCS, while professionals, those with the highest skill level and belonging to top management and independent profession category had the highest BCS. The parametric analysis confirmed this pattern. Considering elementary occupations as reference, all occupations but Craft and related trades had a hazard ratio (HR) below 1. Among professionals, technicians and associate professionals, and clerks, the protective effect of occupation was statistically significant and remained unchanged after adjustment for age, calendar period, registry, nationality, and histological type. After adjusting for tumor stage, the HRs increased only slightly, though turned non-significant. The same effect was observed in top management and independent professions and supervisors, low level management and skilled laborers, compared to unskilled employees. Conclusion: These results suggest that work-related factors may affect BCS. Yet, this study was conducted using a limited set of covariates and a relatively small study sample. Therefore, further larger studies are needed for more detailed analyses of at risk occupations and working conditions and assessing the potential interaction between work-related variables and tumor stage.

Estimating 10-year risk of lung and breast cancer by occupation in Switzerland.

Introduction: Lung and breast cancer are important in the working-age population both in terms of incidence and costs. The study aims were to estimate the 10-year risk of lung and breast cancer by occupation and smoking status and to create easy to use age-, and sex-specific 10-year risk charts. Methods: New lung and breast cancer cases between 2010 and 2014 from all 5 cancer registries of Western Switzerland, matched with the Swiss National Cohort were used. The 10-year risks of lung and breast cancer by occupational category were estimated. For lung cancer, estimates were additionally stratified by smoking status using data on smoking prevalence from the 2007 Swiss Health Survey. Results: The risks of lung and breast cancer increased with age and were the highest for current smokers. Men in elementary professions had a higher 10-year risk of developing lung cancer compared to men in intermediate and managerial professions. Women in intermediate professions had a higher 10-year risk of developing lung cancer compared to elementary and managerial professions. However, women in managerial professions had the highest risk of developing breast cancer. Discussion: The 10-year risk of lung and breast cancer differs substantially between occupational categories. Smoking creates greater changes in 10-year risk than occupation for both sexes. The 10-year risk is interesting for both patients and professionals to inform choices related to cancer risk, such as screening and health behaviors. The risk charts can also be used as public health indicators and to inform policies to protect workers.

Work-Related Factors and Lung Cancer Survival: A Population-Based Study in Switzerland (1990-2014).

While previous Swiss studies have demonstrated differences in lung cancer mortality between occupational groups, no estimates are available on the association of occupation-related factors with lung cancer survival. This study aimed at determining whether occupation or work-related factors after diagnosis affect lung cancer survival. We used cancer registry records to identify lung cancer patients diagnosed between 1990 and 2014 in western Switzerland (n = 5773) matched with the Swiss National Cohort. The effect of occupation, the skill level required for the occupation, and the socio-professional category on 5-year lung cancer survival was assessed using non-parametric and parametric methods, controlling for histological type and tumour stage. We found that the net survival varied across skill levels and that the lowest skill level was associated with worse survival in both men and women. In the parametric models with minimal adjustment, we identified several occupational groups at higher risk of mortality compared to the reference category, particularly among men. After adjustment for histological type of lung cancer and tumour stage at diagnosis, most hazard ratios remained higher than 1, though non-statistically significant. Compared to top managers and self-employed workers, workers in paid employment without specific information on occupation were identified as the most at-risk socio-professional category in nearly all models. As this study was conducted using a relatively small sample and limited set of covariates, further studies are required, taking into account smoking habits and administrated cancer treatments. Information on return to work and working conditions before and after lung cancer diagnosis will also be highly valuable for analysing their effect on net lung cancer survival in large nationwide or international studies. Such studies are essential for informing health and social protection systems, which should guarantee appropriate work conditions for cancer survivors, beneficial for their quality of life and survival.

Occupational Factors and Socioeconomic Differences in Breast Cancer Risk and Stage at Diagnosis in Swiss Working Women.

Socioeconomic differences in breast cancer (BC) incidence are driven by differences in lifestyle, healthcare use and occupational exposure. Women of high socioeconomic status (SES) have a higher risk of BC, which is diagnosed at an earlier stage, than in low SES women. As the respective effects of occupation and SES remain unclear, we examined the relationships between occupation-related variables and BC incidence and stage when considering SES. Female residents of western Switzerland aged 18−65 years in the 1990 or 2000 census, with known occupation, were linked with records of five cancer registries to identify all primary invasive BC diagnosed between 1990 and 2014 in this region. Standardized incidence ratios (SIRs) were computed by occupation using general female population incidence rates, with correction for multiple comparisons. Associations between occupation factors and BC incidence and stage at diagnosis were analysed by negative binomial and multinomial logistic regression models, respectively. The cohort included 381,873 women-years and 8818 malignant BC, with a mean follow-up of 14.7 years. Compared with reference, three occupational groups predominantly associated with a high socioprofessional status had SIRs > 1: legal professionals (SIR = 1.68, 95%CI: 1.27−2.23), social science workers (SIR = 1.29; 95%CI: 1.12−1.49) and some office workers (SIR = 1.14; 95%CI: 1.09−1.20). Conversely, building caretakers and cleaners had a reduced incidence of BC (SIR = 0.69, 95%CI: 0.59−0.81). Gradients in BC risk with skill and socioprofessional levels persisted when accounting for SES. A higher incidence was generally associated with a higher probability of an early-stage BC. Occupation and SES may both contribute to differences in risk and stage at diagnosis of BC.

Research on occupational diseases in the absence of occupational data: a mixed-method study among cancer registries of Western Switzerland.

The contribution of occupation-related diseases to the global burden of disease is greatly underestimated, mainly due to a shortage of occupational exposure data. This problem is particularly salient in Switzerland, where no estimates of occupation-related disease burden exist, even for the well-recognised occupational cancers, such as malignant pleural mesothelioma and lung cancer. To overcome this situation, we launched a research project "Examining Cancers and Labour Indicators to assess the Burden" (ExCaLIBur). Within this project, we aimed to assess the need for and quality (i.e., completeness, accuracy and precision) of occupation registration in all cancer registries of Western Switzerland. We also aimed to find a relevant and feasible strategy to collect this information in the future. We applied a mixed research method. We observed that, independently of the level of precision (5-3-2-1-digit aggregation level), the accuracy was lesser in the registries that were able to actively search and verify occupational information. Overall, the distinction of occupations based on the 3-digit code presents an acceptable compromise in terms of precision. Having such occupations registered in all, or most, Swiss cancer registries routinely would obviously be valuable for epidemiological surveillance of occupational cancers in Switzerland. However, it seems less obvious how these data could fulfill the research objectives, since a better precision than 3-digit occupational coding is challenging to achieve. Currently, the collection of occupational data by the Swiss cancer registries remains feasible in the frame of specific research projects on occupational cancers. However, available data sources, as well as lack of financial and human resources, will continue to affect quality of the collected occupation data. Therefore, the usage of the standardised questionnaire retracing the individual occupational history to enable further assessment of individual exposure to potential occupational hazards is recommended. However, this approach will disable the Swiss registries to insuring their epidemiological surveillance mission with respect to occupational cancers in Switzerland, for which national statistics remain limited.

Correction to: The relative risk of second primary cancers in Switzerland: a population-based retrospective cohort study.

Following publication of the original article [1], an error was reported in the author group. The correct author group should read as follows.

The relative risk of second primary cancers in Switzerland: a population-based retrospective cohort study.

BACKGROUND: More people than ever before are currently living with a diagnosis of cancer and the number of people concerned is likely to continue to rise. Cancer survivors are at risk of developing a second primary cancer (SPC). This study aims to investigate the risk of SPC in Switzerland. METHODS: The study cohort included all patients with a first primary cancer recorded in 9 Swiss population-based cancer registries 1981-2009 who had a minimum survival of 6 months, and a potential follow-up until the end of 2014. We calculated standardized incidence ratios (SIR) to estimate relative risks (RR) of SPC in cancer survivors compared with the cancer risk of the general population. SIR were stratified by type of first cancer, sex, age and period of first diagnosis, survival period and site of SPC. RESULTS: A total of 33,793 SPC were observed in 310,113 cancer patients. Both male (SIR 1.18, 95%CI 1.16-1.19) and female (SIR 1.20, 95%CI 1.18-1.22) cancer survivors had an elevated risk of developing a SPC. Risk estimates varied substantially according to type of first cancer and were highest in patients initially diagnosed with cancer of the oral cavity and pharynx, Hodgkin lymphoma, laryngeal, oesophageal, or lung cancer. Age-stratified analyses revealed a tendency towards higher RR in patients first diagnosed at younger ages. Stratified by survival period, risk estimates showed a rising trend with increasing time from the initial diagnosis. We observed strong associations between particular types of first and SPC, i.e. cancer types sharing common risk factors such as smoking or alcohol consumption (e.g. repeated cancer of the oral cavity and pharynx (SIRmales 20.12, 95%CI 17.91-22.33; SIRfemales 37.87, 95%CI 30.27-45.48). CONCLUSION: Swiss cancer survivors have an increased risk of developing a SPC compared to the general population, particularly patients first diagnosed before age 50 and those surviving more than 10 years. Cancer patients should remain under continued surveillance not only for recurrent cancers but also for new cancers. Some first and SPCs share lifestyle associated risk factors making it important to promote healthier lifestyles in both the general population and cancer survivors.

Socioeconomic and demographic inequalities in stage at diagnosis and survival among colorectal cancer patients: evidence from a Swiss population-based study.

Socioeconomic inequalities in cancer stage at diagnosis and survival are important public health issues. This study investigates the association between socioeconomic position (SEP) and colorectal cancer (CRC) stage at diagnosis and survival in Switzerland, a European country with highest level of medical facilities and life expectancy. We used population-based CRC data from seven Swiss cantonal cancer registries 2001-2008 (N = 10,088) linked to the Swiss National Cohort (SNC). Follow-up information was available until the end of 2013. SEP was estimated based on education. The association between cancer stage and SEP was assessed using logistic regression models including cancer localization (colon/rectum), sex, age, civil status, urbanity of residence, language region, and nationality (Swiss/non-Swiss). Survival was analyzed using competing risk regressions reporting subhazard ratios (SHRs) for the risk of dying due to CRC. We observed a social gradient for later stage CRC with adjusted odds ratios (ORs) of 1.11 (95% CI: 0.97-1.19) and 1.28 (95% CI: 1.08-1.50) for middle and low SEP compared to high SEP. Further, single compared to married people had elevated odds of being diagnosed at later stages. Survival was lower in patients with CRC with low SEP in the unadjusted model (SHR: 1.18, 95% CI: 1.07-1.30). After adjustment for stage at diagnosis and further sociodemographic characteristics, significant survival inequalities by SEP disappeared but remained for non-Swiss compared to Swiss citizens and for patients living in nonurban areas compared to their urban counterparts. Swiss public health strategies should facilitate equal access to CRC screening and optimal CRC care for all social groups and in all regions of Switzerland.

Socioeconomic and demographic disparities in breast cancer stage at presentation and survival: A Swiss population-based study.

We explored socioeconomic and demographic disparities in breast cancer (BC) stage at presentation and survival in a Swiss population-based sample of female BC patients linked to the census-based Swiss National Cohort. Tumor stage was classified according to Surveillance, Epidemiology and End Results Program summary stage (in situ/localized/regional/distant). We used highest education level attained to estimate SEP (low/middle/high). Further demographic characteristics of interest were age at presentation (30-49/50-69/70-84 years), living in a canton with organized screening (yes/no), urbanity of residence (urban/peri-urban/rural), civil status (single/married/widowed/divorced) and nationality (Swiss/non-Swiss). We used ordered logistic regression models to analyze factors associated with BC stage at presentation and competing risk regression models for factors associated with survival. Odds of later-stage BC were significantly increased for low SEP women (odds ratio 1.19, 95%CI 1.06-1.34) compared to women of high SEP. Further, women living in a canton without organized screening program, women diagnosed outside the targeted screening age and single/widowed/divorced women were more often diagnosed at later stages. Women of low SEP experienced an increased risk of dying from BC (sub-hazard ratio 1.22, 95%CI 1.05-1.43) compared to women of high SEP. Notably, these survival inequalities could not be explained by socioeconomic differences in stage at presentation and/or other sociodemographic factors. It is concerning that these social gradients have been observed in a country with universal health insurance coverage, high health expenditures and one of the highest life expectancies in the world.

Evaluation of completeness of case ascertainment in Swiss cancer registration.

This is the first comprehensive evaluation of completeness of case ascertainment in Swiss cancer registration. There is currently no method available that is considered to be the gold standard. Apart from simple measures such as the proportion of cases where registration was initiated by a death certificate and the proportion of diagnoses on the basis of histology or cytology/haematology, we applied two dedicated approaches: (i) the semiquantitative method of comparing the mortality to incidence rate ratio with relative survival (MI-Surv method) and (ii) the Flow method, which provides a quantitative estimate for the completeness depending on time since diagnosis. All 10 Swiss cancer registries in operation since at least 2006 and providing the required parameters were included. Simple and dedicated methods showed high completeness across all cancer registries and for most cancer types tested, with the notable exception of lymphoid leukaemia.

Second neoplasms after oesophageal cancer.

The authors considered the incidence of second neoplasms among 1,672 oesophageal cancers diagnosed between 1974 and 2004 in the Cancer Registries of the Swiss Cantons of Vaud and Neuchâtel, and followed-up to 2004. A total of 141 second neoplasms were observed versus 38.5 expected, corresponding to a standardized incidence ratio (SIR) of 3.7 (95% confidence interval: 3.1-4.3). The SIRs were statistically significant for cancers of the oral cavity and pharynx (57.3), larynx (24.3), lung (6.6) and intestines (2.6). The SIRs were higher in subjects diagnosed below age 50 and in the first year after diagnosis. The SIR of upper digestive and respiratory tract neoplasms was higher for oesophageal cancers diagnosed in the upper (87.5) and middle (68.1), as compared with the lower third (19.4). There was no rise of second oral, pharyngeal and laryngeal cancer with advancing age, and their incidence tended indeed to decline from 100/1,000 at age 40-49 to 25/1,000 at age 70-79. There was no tendency to rise with age in the incidence of first oesophageal cancer in subjects who subsequently developed another upper digestive or respiratory tract neoplasm. The excess risks of upper digestive and respiratory tract neoplasms are attributable to increased diagnosis and registration of second neoplasms following a diagnosis of oesophageal cancer, as well as to heavy tobacco and alcohol consumption in oesophageal cancer cases. The absence of rise in incidence with age is also compatible with the existence of a subset of the population of susceptible individuals.

Second primary oral and pharyngeal cancers in subjects diagnosed with oral and pharyngeal cancer.

Patients diagnosed with oral and pharyngeal (OP) cancer have a substantial excess risk of second OP cancer, but risk quantification is still uncertain and scanty information is available on the absolute excess risk of second OP cancer. We considered the risk of second OP primary cancer in a population-based series of 3,092 first primary OP cancers registered between 1974 and 2003 in the Swiss Cantons of Vaud and Neuchâtel (total population of about 786,000 inhabitants). A total of 233 second OP cancers were registered, versus 7.4 expected, corresponding to a SIR of 31.7 (95% confidence interval (CI) 27.7-36.0). The SIR was 68.5 in the first year after diagnosis of the first primary, and declined thereafter, leveling around 20. The SIR was 30.7 when the site of first neoplasm was the oral cavity, 42.5 for the tongue and 28.1 for the oropharynx or hypo-pharynx. Corresponding values for topographies of second primaries were 28.8, 50.4 and 26.2. The cumulative risk of second OP cancer 15 years after diagnosis of first OP cancer approached 22% in men and 17% in women. The incidence of first primaries increased over 20-fold between age 30-39 and 70-79, whereas there was no rise with age for second neoplasms.

High incidence of second basal cell skin cancers.

We considered the risk of second basal cell cancers (BCC) of the skin using a population-based series of 1,868 BCC collected between 1976 and 1985 in the Swiss Cantons of Vaud and Neuchâtel, and followed-up to the end of 2003. Overall, 507 second BCC were observed versus 59.98 expected, corresponding to a standardized incidence ratio (SIR) of 8.45 (95% CI: 7.73-9.22). The SIRs were similar in men and women in subsequent calendar periods, but tended to decline with advancing age at diagnosis of first BCC, from 13.98 below age 50 to 7.13 at age 70 or over. Consequently, the rate of first BCC increased to approximately 30-fold between 7/100,000 at age 30-39 and 200/100,000 at age 70-79, but the rate of second BCC increased only about 3-fold between 31/1,000 at age 30-39 and 110/1,000 at age 70-79. The cumulative risk of second BCC was 11% at 5 years, 21% at 10 years and 40% at 20 years. This study indicates that the relative (but not the absolute) risk of second BCC is greater at younger age and declines with advancing age, and is therefore compatible with an excess baseline risk in a population of susceptible individuals.

Skin cancer in survivors of childhood and adolescent cancer.

The incidence of basal cell carcinoma (BCC) has been related to ionizing radiation, particularly for exposure occurring at young age. In this study, we considered the incidence of second skin neoplasms in long-term survivors from childhood cancer. We considered second primary cancers occurring among 776 subjects (436 males, 340 females) with first primary cancer diagnosed before age 20 years, between 1974 and 2001, in the Swiss Cantons of Vaud and Neuchâtel (786,000 inhabitants). Five BCC were observed versus 0.43 expected (standardized incidence ratio: 11.6, 95% confidence interval: 3.7-27.1). No case of cutaneous squamous cell carcinoma, nor of malignant melanoma was observed. The estimated radiation doses at 1mm through the skin ranged between 7 and 27 Sv. These data confirm that BCC are strongly related to ionizing radiation exposure in childhood. All the BCC were located within the radiation field, thus indicating that ionizing radiation is the key aetiological factor, even in the absence of any meaningful interaction with UV.