Pigmentation, UV exposure, physical activity and risk and prognosis of cutaneous melanoma and squamous cell carcinoma
With data from the Swedish Women's Lifestyle and Health (WLH) and Norwegian Women and Cancer (NOWAC) cohorts, we were the first to prospectively study pigmentation factors and UV exposure in relation to risk of cutaneous melanoma (Veierød et al, 2003; Veierød et al, 2010). Our research in the unique NOWAC cohort, continued with studies of sun habits (Ghiasvand et al, 2015); solarium use and risk of melanoma (Ghiasvand et al, 2017) and cutaneous squamous cell carcinoma (Veierød et al, 2014; Lergenmuller et al, 2019); sunscreen use and risk of melanoma (Ghiasvand et al, 2016) and squamous cell carcinoma (Lergenmuller et al, 2022), and reviews of sunscreen use and melanoma (Rueegg et al, 2018) and squamous cell carcinoma (Lergenmuller et al, 2025); lifetime sunburn trajectories and risk of melanoma and squamous cell carcinoma (Lergenmuller et al, 2022); pigmentation factors, UV exposure and melanoma risk on different body sites (Ghiasvand et al, 2019); UV exposure and DNA methylation in blood leukocytes (Page et al, 2020; Page et al, 2022); reproductive factors, menopausal hormone therapy and melanoma risk (Støer et al, 2019, Støer et al, 2021); and physical activity (PA) and melanoma risk investigating overall and seasonal PA (Perrier et al, 2021) and PA life-course trajectories (Perrier et al, 2022). Some of the above factors may also be relevant for prognosis after melanoma diagnosis. We have studied pigmentation factors, prediagnosis PA and melanoma thickness (Ghiasvand et al, 2021 and Perrier et al, 2023, respectively); and pigmentation factors and prediagnosis PA and melanoma-specific mortality (Ahimbisibwe et al, 2023; Perrier et al, 2025).
Skin cancer incidence and mortality
Using data from the Cancer Registry of Norway, we study, in the Norwegian population, the incidence and mortality of squamous cell carcinoma (SCC) (Robsahm et al, 2015); prognostic factors after melanoma diagnosis (Helsing et al, 2016; Robsahm et al, 2018); additive frailty models and clustering of melanoma in families (Brathovde et al, 2023); rates of second tumor, metastasis, and death from SCC in patients with and without transplant-associated immunosuppression (Gjersvik et al, 2023); incidence and factors associated with second primary melanoma (Ghiasvand et al, 2024); and trends in melanoma incidence by tumor thickness (Rimal et al, 2024).
Uveal melanoma: a rare, severe and little studied cancer
Uveal melanoma is less studied than cutaneous melanoma, the most common type of melanoma. With data from the Cancer Registry of Norway, we have studied the trends in incidence and survival for uveal melanoma in Norway, 1993-2021.
Risk of cancer in petroleum offshore workers
In collaboration with the Cancer Registry of Norway, we study exposure-related risks of cancer in petroleum workers. After publishing the cohort profile of the Norwegian Offshore Petroleum Workers (NOPW) cohort explaining how exposures are recorded for cohort and case-cohort analyses (Stenehjem et al, 2021); we have discussed cancer history based selection and censoring (Berge et al, 2022); and investigated UV exposure and skin cancer risk (Liu et al, 2021); night shift work and male (Liu et al, 2021) and female (Liu et al, 2022) breast cancer risk; night shift work and risk of aggressive prostate cancer (Berge et al, 2022); benzene and other hydrocarbons and bladder cancer risk (Shala et al, 2023); benzene and risk of lung cancer (Babigumira et al, 2023) and colorectal cancer (Babigumira et al, 2025); exposure to fibres and pleural mesothelioma risk (Berge et al, 2024); and occupational exposures and kidney cancer with analysis of components of healthy worker survivor bias (Shala et al, 2026).
Risk of cancer in firefighters
In collaboration with the Cancer Registry of Norway, we have described work conditions and practices in Norwegian fire departments from 1950 until today (Jakobsen et al, 2020); developed indicators for specific occupational firefighting exposures (Marjerrison et al, 2023); investigated cancer incidence in the newly established Norwegian Fire Departments Cohort with 58 years of follow-up (Marjerrison et al, 2022); compared standardized incidence and mortality ratios (Marjerrison et al, 2022); investigated age at diagnosis, prognostic factors, and survival of prostate cancer in Norwegian firefighters, military employees, pilots and police officers 1960-2017 (Jakobsen et al, 2022); and studied the associations between occupational firefighting exposure and urinary tract (Marjerrison et al, 2023) and prostate cancer (Marjerrison et al, 2025) risk.
Prescribed drugs and cancer
In a collaboration with the Cancer Registry of Norway, a protocol for a population-based case-control study, merging nation-wide registries to study selected drugs and melanoma risk was established (Berge et al, 2019), and use of antidepressants (Berge et al, 2020), immunomodulating drugs (Berge et al, 2020), antihypertensive drugs (Ghiasvand et al, 2022), and statins (Ghiasvand et al, 2023) were investigated. Associations between aspirin use and detection of colorectal polyps and cancer were investigated in a large colorectal screening trial (Nafisi et al, 2023); and the association between aspirin use and colorectal cancer risk in a large nationwide cohort study (Nafisi et al, 2024).
Bias in observational studies
Measurement errors, misclassification and missing data are important sources of bias in observational studies. Our interest in this area started with methodological research on bias in Poisson regression coefficients (Veierød et al, 2001); clarification of under what conditions a naive analysis using a misclassified predictor will induce bias for the regression coefficients of other perfectly measured predictors in the model (Buonaccorsi et al, 2005); and power of the Cochrane-Armitage test for trend in the presence of misclassification (Buonaccorsi et al, 2014). We also studied measurement errors in self-reported melanoma risk factors (Veierød et al, 2008; Parr et al, 2009); compared methods for handling missing data in food frequency questionnaires (Parr et al, 2008); documented errors in important prognostic factors such as tumor thickness of melanoma (Veierød et al, 2018) and breast cancer diameter (Tsuruda et al, 2020); studied clinical suspicion sensitivity of nodular and superficial spreading melanoma (Robsahm et al, 2021); discussed cancer history-based selection and censoring (Berge et al, 2022); conducted a pilot to study of agreement between different pathologists' assessments of histopathological slides of melanocytic skin lesions and diagnostic drift over time (Gjersvik et al, 2022); and studied components of healthy worker survivor bias (Shala et al, 2026).