Physical activity, cardiorespiratory fitness and risk of cutaneous malignant melanoma: Systematic review and meta-analysis

Adolescent cardiorespiratory fitness and risk of cancer in late adulthood: A nationwide sibling-controlled cohort study in Sweden

BACKGROUND

Cardiorespiratory fitness has been linked to both lower and higher risks of cancer, but the evidence comes from observational analysis which may be influenced by unobserved confounders and bias processes. We aimed to examine the associations between adolescent cardiorespiratory fitness and risk of cancer in late adulthood while addressing the unknown influence of unobserved familial confounders and diagnostic bias processes.

METHODS AND FINDINGS

We conducted a sibling-controlled cohort study with registry linkage based on all Swedish men who participated in mandatory military conscription examinations from 1972 to 1995 and who completed standardized cardiorespiratory fitness testing. The outcomes were overall cancer diagnosis and cancer mortality, and 14 site-specific cancers (diagnosis or death), ascertained using the National Patient Register and Cause of Death Register until 31 December 2023. A total of 1,124,049 men, including 477,453 full siblings, with a mean age of 18.3 years at baseline, were followed until a median (maximum) age of 55.9 (73.5) years, during which 98,410 were diagnosed with cancer and 16,789 died from cancer (41,293 and 6,908 among full siblings respectively). In cohort analysis, individuals in the highest quartile of fitness had a lower risk of overall cancer mortality (adjusted hazard ratio [HR]: 0.71, 95% confidence interval [CI] 0.67, 0.76; P < 0.001) compared to the lowest quartile, corresponding to a standardized cumulative incidence (1-Survival) difference of -0.85 (95% CI [-1.00, -0.71]) percentage points at 65 years of age. Individuals in the highest quartile of fitness also had lower risks (HRs ranging from 0.81 to 0.49, incidence differences ranging from -0.13 to -0.32 percentage points; P < 0.001 for all) of rectum, head and neck, bladder, stomach, pancreas, colon, kidney, liver, bile ducts, and gallbladder, esophagus, and lung cancer. Yet, individuals in the highest quartile of fitness had higher risks of prostate (HR: 1.10, 95% CI [1.05, 1.16]; P < 0.001, incidence difference: 0.48 percentage points, 95% CI [0.23, 0.73]) and skin cancer (e.g., non-melanoma HR: 1.44, 95% CI [1.38, 1.50]; P < 0.001, incidence difference: 1.84 percentage points, 95% CI [1.62, 2.05]). Individuals in the highest quartile of fitness had a higher risk of overall cancer diagnosis (HR: 1.08, 95% CI [1.06, 1.11]; P < 0.001, incidence difference: 1.32 percentage points, 95% CI [0.94, 1.70]), results driven by prostate and skin cancer being the most common types of cancer. When comparing full siblings, and thereby controlling for unobserved shared confounders, the lower risk of overall cancer mortality remained (HR: 0.78, 95% CI [0.68, 0.89]; P < 0.001, incidence difference: -0.61 percentage points, 95% CI [-0.93, -0.28]), while the excess risk of prostate (HR: 1.01, 95% CI [0.90, 1.13]; P = 0867, incidence difference: 0.05 percentage points, 95% CI [-0.50, 0.60]), skin (e.g., non-melanoma HR: 1.09, 95% CI [0.99, 1.20]; P = 0.097, incidence difference: 0.40 percentage points, 95% CI [-0.07, 0.87]), and overall cancer diagnosis (HR: 1.00, 95% CI [0.95, 1.06]; P = 0.921, incidence difference: 0.04 percentage points, 95% CI [-0.80, 0.88]) attenuated to the null. For other site-specific cancers, sibling comparisons results varied, with more attenuation for melanoma, kidney, stomach, bladder, pancreas, and liver, bile ducts, and gallbladder cancer, while associations with lung, colon, head and neck, and esophagus cancer seemed to attenuate less. The findings were confirmed through an extensive set of sensitivity analyses. The main limitations of this study include the lack of inclusion of female participants, lack of data on other risk factors such as smoking, alcohol consumption, and physical activity, and only adjustment for the unobserved confounders which are shared between full siblings.

CONCLUSIONS

Higher levels of adolescent cardiorespiratory fitness were associated with lower overall cancer mortality in late adulthood, a finding that persisted in sibling comparisons. However, the influence of unobserved familial confounding appeared to vary by cancer type and be more pronounced for cancer diagnoses than for mortality. This may suggest a need for robust causal methods to triangulate results, rather than relying on correlations alone, to better inform public health efforts.

A genetically informed study reveals modifiable pathways in skin cancer

BACKGROUND

Identifying modifiable risk factors is essential for the prevention of skin cancer; however, establishing causality can be challenging in conventional epidemiological studies. This study aimed to determine the causal associations of potentially modifiable risk factors with skin cancer using Mendelian randomization (MR).

METHODS

Genetic instruments for 53 risk factors, including socioeconomic status, dietary and lifestyle factors, anthropometric measures, medication use, and comorbidities, were identified from previous genome-wide association studies. Two-sample MR analyses were performed using summary statistics for three major types of skin cancer: melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC). Findings were verified using multiple MR methods under different assumptions and replication datasets.

RESULTS

Genetic liability to sunburn occasions, actinic keratosis, and prior skin cancers was associated with a higher risk of all three types of skin cancer, whereas genetic liability to vitiligo was associated with a lower risk. For specific skin cancer types, genetically predicted higher nevus counts and occupational class were associated with an increased risk of melanoma. Genetic liability to rheumatoid arthritis, type 2 diabetes, and increased physical activity were associated with a lower risk of BCC. Genetically predicated body mass index showed a negative association with BCC, and a positive association with SCC.

CONCLUSIONS

Our study reaffirmed several previously established risk factors and identified novel potential risk factors for skin cancer. Further work is needed to unravel the biological pathways in different skin cancer types and translate our findings to inform public health policies.

Adolescent Cardiorespiratory Fitness and Risk of Cancer in Late Adulthood: Nationwide Sibling-Controlled Cohort Study

Objective

To investigate whether the higher risks of certain cancers associated with high cardiorespiratory fitness can be explained by increased detection and unobserved confounders.

Design

Nationwide sibling-controlled cohort study of adolescents.

Setting

Sweden.

Participants

1 124 049 men of which 477 453 were full siblings, who underwent mandatory military conscription examinations between 1972 and 1995 at a mean age of 18.3 years.

Main outcome measures

Hazard ratios (HR) and 95% confidence intervals (CI) of overall cancer diagnosis and cancer mortality, and 14 site-specific cancers (diagnosis or death), as recorded in the Swedish National Patient Register or Cause of Death Register until 31 December 2023, modelled using flexible parametric regressions.

Results

Participants were followed until a median (maximum) age of 55.9 (73.5) years, during which 98 410 were diagnosed with cancer and 16 789 had a cancer-related death (41 293 and 6908 among full siblings respectively). The most common cancers were non-melanoma skin (27 105 diagnoses & 227 deaths) and prostate cancer (24 211 diagnoses & 869 deaths). In cohort analysis, those in the highest quartile of cardiorespiratory fitness had a higher risk of prostate (adjusted HR 1.10; 95% CI: 1.05 to 1.16) and skin cancer (e.g., non-melanoma HR 1.44; 1.37 to 1.50) compared to those in the lowest quartile, which led to a higher risk of any type of cancer diagnosis (HR 1.08; 1.06 to 1.11). However, those in the highest quartile had a lower risk of cancer mortality (HR 0.71; 0.67 to 0.76). When comparing full siblings, and thereby controlling for all behavioural, environmental, and genetic factors they share, the excess risk of prostate (HR 1.01; 0.90 to 1.13) and skin cancer (e.g., non-melanoma HR 1.09; 0.99 to 1.20) attenuated to the null. In contrast, the lower risk of overall cancer mortality was still statistically significant after control for such shared confounders (HR 0.78; 0.68 to 0.89). For other site-specific cancers, the influence of such confounding tended to vary, but none showed the same excess risk as prostate and non-melanoma skin cancer.

Conclusions

The association between high levels of adolescent cardiorespiratory fitness and excess risk of some cancers, such as prostate and non-melanoma skin cancer, appears to be fully explained by unobserved confounders shared between full siblings. However, the protective association with cancer mortality persists even after control for such confounding.

Associations of Dietary Factors with Cutaneous Melanoma: A Case-Control Study in Greece with Literature Review

INTRODUCTION

It has been postulated that nutrition may influence the risk for cutaneous melanoma (CM); therefore, we aimed to assess the associations of food groups and individual nutrient intakes with CM in a Greek population.

METHODS

In this case-control study, 151 patients with histologically confirmed CM, newly diagnosed and treated in the Oncology Department of the "Laikon" University Hospital (Athens, Greece), and 151 age- and sex-matched healthy individuals residing in the Athens metropolitan area, recruited among participants for routine health examinations, were included. All participants completed a questionnaire comprising anthropometric measurements, sociodemographic, lifestyle, and health-related variables. A validated, semiquantitative food frequency questionnaire was used to assess average consumption of 136 food items during the 12 months preceding the onset of disease. Multivariate conditional regression models were used to derive odds ratios (ORs) with 95% confidence intervals (95% CI) regarding the association of nine food groups and seven macronutrients with CM.

RESULTS

Statistically significant positive associations with CM were found with higher energy intake (OR: 1.67, 95% CI: 1.22-2.30) and intake of saturated fatty acids (OR: 2.28, 95% CI: 1.00-5.28), after adjusting for sun sensitivity, major depression history, and alcohol intake. Inverse associations with higher intake of milk and dairy products (OR: 0.65, 95% CI: 0.48-0.88), fruits (OR: 0.68, 95% CI: 0.51-0.90), added lipids (OR: 0.65, 95% CI: 0.47-0.91), and sugars and syrups (OR: 0.70, 95% CI: 0.53-0.93) were also observed.

CONCLUSIONS

Beyond intrinsic risk factors, our results support associations of CM with multiple food groups and nutrients; if confirmed by prospective studies, these findings can add further knowledge about this fatal cancer.

Leisure-time physical activity, daily sitting time, and mortality among US skin cancer survivors

PURPOSE

To investigate the long-term effect of sitting time and physical activity after a skin cancer diagnosis.

METHODS

A cohort of a nationally representative sample of skin cancer survivors (n=862) and non-cancer adults (n=13691) ≥50 years from the US National Health and Nutrition Examination Survey. Mortality data were linked through December 31, 2019.

RESULTS

During up to 13.2 years of follow-up (median, 6.3 years; 94,093 person-years), 207 deaths (cancer: 53) occurred in skin cancer survivors and 1970 (cancer: 414) in non-cancer adults. After adjusting for covariates and skin cancer type, being active was associated with lower risks of all-cause (HR=0.69; 95% CI: 0.47 to 1.00) and non-cancer (HR=0.59; 95% CI: 0.36 to 0.97) mortality compared to being inactive among skin cancer survivors. Meanwhile, sitting 8 h/d was associated with higher risks of all-cause (HR=1.72; 95% CI: 1.11 to 2.67) and non-cancer (HR=1.76; 95% CI: 1.07 to 2.92) mortality compared to sitting <6 h/d. In the joint analysis, inactive skin cancer survivors sitting >8 h/d had the highest mortality risks from all-cause (HR=2.26; 95% CI: 1.28 to 4.00) and non-cancer (HR=2.11; 95% CI,1.10 to 4.17). Additionally, the associations of LTPA and sitting time with all-cause and cause-specific mortality did not differ between skin cancer survivors and non-cancer adults (all P for interaction>0.05) CONCLUSION: The combination of prolonged sitting and lack of physical activity was associated with elevated risks of all-cause and non-cancer deaths among US skin cancer survivors. Skin cancer survivors could benefit from maintaining a physically active lifestyle.

Cross-sectional study of physical activity among long-term melanoma survivors and population controls

Physical activity has been associated with improved outcomes among cancer survivors of various malignancies; however, this topic is understudied among melanoma survivors. Our objective was to determine whether long-term melanoma survivors are less likely to meet American Cancer Society physical activity guidelines than non-melanoma population controls. We conducted a cross-sectional survey in 2015 to follow up participants from a case-control study of melanoma and population controls in Minnesota. The primary outcome was meeting American Cancer Society recommendations for healthy physical activity levels. Physical activity, sun protection practices and time spent outside were compared between survivors and controls using generalized linear regression models. Melanoma survivors (N = 724) and controls (N = 639) were similar with the exceptions of daily hours spent outside, sun protection scores, skin tone, and smoking status. Half (50.8%) of melanoma survivors reported meeting the physical activity guidelines, compared to 39.7% of controls (p < 0.0001), with an 11% (95% CI 0.05-0.17) difference after adjusting for potential confounders. While long-term melanoma survivors were more likely to meet American Cancer Society physical activity guidelines than population controls, nearly 50% did not meet recommendations. This finding is concerning given the known improvements in quality of life and survival among physically active cancer survivors. Opportunities remain to promote physical activity among melanoma survivors. Health communications that promote outdoor exercise, in particular, should include advice about sun protection.

Life-Course Trajectories of Physical Activity and Melanoma Risk in a Large Cohort of Norwegian Women

Purpose

Physical activity (PA) is a cornerstone in disease prevention and varies throughout life. A pooled analysis of cohort studies and a meta-analysis of cohort studies found positive associations between PA and melanoma risk. However, previous studies focused on PA at specific ages and often lacked information on ultraviolet radiation (UVR) exposure. Using the population-based Norwegian Women and Cancer (NOWAC) cohort, including information on PA and UVR exposure, we estimated life-course PA trajectories from adolescence to adulthood and their associations with melanoma.

Methods

Total PA across different domains (recreation, occupation, transport, household) was reported for ages 14 and 30 years, and when responding to the questionnaire (31-76 years) using a 10-point scale, validated to rank PA levels in Norwegian females. We estimated life-course PA trajectories using a latent class mixed model in 152,248 women divided into three subcohorts depending on age at questionnaire completion: 31-39 (n = 27,098), 40-49 (n = 52,515) and ≥50 years (n = 72,635). The unique 11-digit identity number of Norwegian citizens was used to link NOWAC to the Cancer Registry of Norway for information on cancer diagnoses, emigration and death. Associations between PA trajectories and melanoma risk were estimated in each subcohort using multivariable Cox regression.

Results

Five classes of individual life-course PA trajectories were identified in subcohort 31-39 years (low, moderate, high, decreasing, increasing PA) and four in subcohorts 40-49 and ≥50 years (low, moderate, high, decreasing PA). No significant association was found between life-course PA trajectories and melanoma risk in any subcohort. Hazard ratios (95% confidence intervals) for the high versus moderate trajectory were 0.92 (0.66-1.29), 1.15 (0.97-1.37) and 0.90 (0.78-1.05) for subcohorts 31-39, 40-49 and ≥50 years, respectively.

Conclusion

Our results do not support a positive association between PA and melanoma risk found in previous studies, which is important for public health guidelines promoting regular PA.

Knowledge, Behaviour and Attitudes Related to Sun Exposure in Sportspeople: A Systematic Review

People who practice outdoor sports have an increased risk of skin cancer as they are exposed to high doses of ultraviolet (UV) radiation. Recent studies have shown that in many athletes, sun protection behaviours are inadequate, with the risk that this entails. The aim of this review is to collect the information published to date about the knowledge, attitudes and habits of athletes in relation to sun exposure and its risks. A systematic review was conducted using PubMed and Embase with the search algorithm "(skin cancer OR melanoma) AND (exercise OR sport OR athletes)". All studies analysing the knowledge, attitudes and habits of photoprotection in athletes were included. A total of 2,365 publications were found, of which 23 were selected, including a total of 10,445 sportspeople. The majority of participants declared their voluntary intention to tan and stated that the sun made them feel better, although they also showed concern about possible damage associated with UV radiation. In most studies, less than half of the participants made adequate use of photoprotective measures. In general, most athletes had a high level of knowledge regarding the risk of skin cancer associated with sun exposure. In conclusion, most athletes are aware of the risks associated with UV radiation but do not make adequate use of photoprotective cream. New training programs on photoprotection could help improve athletes' photoprotective behaviour, reducing the incidence of skin cancer and precancerous lesions in this population.

Physical activity and cutaneous melanoma risk: A Norwegian population-based cohort study

Physical activity (PA) is an important factor in cancer prevention, but positive association between PA and risk of cutaneous melanoma found in recent studies may complicate this strategy. Ultraviolet radiation (UVR) exposure during outdoor PA is a plausible explanation for a positive association. We investigated the associations between PA, UVR and melanoma risk in the Norwegian Women and Cancer cohort. Overall PA was reported by 151,710 women, aged 30-75 at inclusion, using a validated 10-point-scale at enrolment and during follow-up, together with recent numbers of sunburns, indoor tanning sessions and weeks on sunbathing vacations. Seasonal outdoor walking and seasonal PAs were recorded in subsamples (n = 102,671 and n = 29,077, respectively). Logistic and Cox regression were used. Mean follow-up was 18.5 years, and 1565 invasive incident melanoma cases were diagnosed. Overall PA was inversely associated with sunburns, while positively associated with sunbathing vacations and indoor tanning. Overall PA was not associated with melanoma risk in all body sites combined (ptrend = 0.61), but reduced risk was found in upper limb melanomas (hazard ratio (HR) = 0.70, 95% confidence interval (CI) 0.51-0.96; high versus low PA). Non-significant reduced risks were found for seasonal outdoor walking >2 h/day versus 30-60 min/day (summer HR = 0.81, 95% CI 0.66-1.00; autumn HR = 0.74, 95%CI 0.55-1.01). Seasonal PAs were not associated with melanoma risk. In conclusion, we found positive associations between overall PA and sunbathing vacations and indoor tanning, and, unlike literature, inverse association between overall PA and sunburns. Our results do not support a positive association between PA and melanoma risk in Norwegian women.

Associations of Physical Activity and Exercise with Health-related Outcomes in Patients with Melanoma During and After Treatment: A Systematic Review

Purpose:

Although exercise medicine is recommended to counter treatment-related side-effects and improve health-related outcomes of patients affected by different cancers, no specific recommendations exist for patients with melanoma. As a result, we systematically examined the current evidence regarding the effects of physical activity and exercise on objectively-measured and patient-reported outcomes among patients with melanoma.

Methods:

Searches were conducted in PubMed, CINAHL, EMBASE, SPORTDiscus, and Web of Science databases. This review included published data involving physical activity or exercise and objectively-measured or patient-reported outcomes of patients with cutaneous melanoma. The quality of included studies was assessed using the McMaster University Critical Appraisal Tool for Quantitative Studies.

Results:

Six studies including 882 patients with melanoma were included. Studies presented heterogeneity of design with 2 cross-sectional surveys, 2 retrospective analyses, and 2 non-randomized intervention trials. No statistically significant change in quality of life, fatigue, physical function, cardiorespiratory fitness, body composition, psychological distress, cognitive function, or treatment-related side-effects were attributable to physical activity or exercise. Importantly, physical activity or exercise during melanoma treatment or into survivorship did not adversely impact patients/survivors.

Conclusion:

In summary, physical activity or exercise did not adversely impact quality of life, objectively-measured or patient-reported outcomes in patients with melanoma. In addition, there is a paucity of quality studies examining the effects of physical activity or exercise on patients with melanoma throughout the cancer care continuum.

Association between physical activity, grip strength and sedentary behaviour with incidence of malignant melanoma: results from the UK Biobank

BACKGROUND

Physical activity has been positively related to malignant melanoma. However, that association may be confounded by ultraviolet radiation (UV), a variable closely related to both outdoor physical activity and malignant melanoma. We examined physical activity, grip strength and sedentary behaviour in relation to risk of malignant melanoma, accounting for relevant confounders using data from a prospective cohort study.

METHODS

In 350,512 UK Biobank participants aged 38-73 years at baseline, physical activity was assessed with a modified version of the International Physical Activity Questionnaire Short Form, grip strength was measured with a hand dynamometer, and sedentary behaviour was recorded with three specific questions. Multivariable hazard ratios (HR) and corresponding 95% confidence intervals (CI) were estimated using Cox proportional hazards regression.

RESULTS

During 7 years of follow-up, 1239 incident malignant melanoma diagnoses were recorded. Physical activity and sedentary behaviour were unrelated to malignant melanoma (HRs 1.01 (95% CI 0.95-1.07) and 1.04 (95% CI 0.97-1.12), respectively), and the initially positive association with grip strength in the basic model (HR 1.23, 95% CI 1.08-1.40) was attenuated after full adjustment (HR 1.10, 95% CI 0.96-1.26).

CONCLUSION

Physical activity, grip strength and sedentary behaviour are not associated with malignant melanoma risk.

Physician skin cancer screening among U.S. military veterans: Results from the National Health Interview Survey

Introduction

Although military veterans are at increased risk for skin cancer, little is known about the extent to which they have been screened for skin cancer. The study objective was to examine the prevalence and correlates of physician skin cancer screening among U.S. military veterans.

Methods

Data were drawn from the National Health Interview Survey. The study sample consisted of 2,826 individuals who reported being military veterans. Receipt of a physician skin examination was measured using a single question that asked participants whether they had ever had all of their skin from head to toe checked for cancer by a dermatologist or some other kind of doctor.

Results

Less than a third (30.88%) of participants reported ever having a physician skin examination. Factors positively associated with receipt of a physician skin examination in a multivariable logistic regression analysis included: older age, greater educational level, non-Hispanic white race/ethnicity, having TRICARE (military) health insurance, greater skin sensitivity to the sun, and engagement in more sun protection behaviors.

Conclusions

The majority of military veterans have never been screened for skin cancer by a physician. Screening rates were higher among individuals with one or more skin cancer risk factors. Future research is warranted to test targeted skin cancer screening interventions for this at risk and understudied population.

Dual Encapsulated Dacarbazine and Zinc Phthalocyanine Polymeric Nanoparticle for Photodynamic Therapy of Melanoma

PURPOSE

Melanoma is an invasive and very aggressive skin cancer due to its multi-drug resistance that results in poor patient survival. There is a need to test new treatment approaches to improve therapeutic efficacy and reduce side effects of conventional treatments.

METHODS

PLA/PVA nanoparticles carrying both Dacarbazine and zinc phthalocyanine was produced by double emulsion technique. The characterization was performed by dynamic light scattering and atomic force microscopy. In vitro photodynamic therapy test assay using MV3 melanoma cells as a model has been performed. In vitro cell viability (MTT) was performed to measure cell toxicity of of nanoparticles with and without drugs using human endothelial cells as a model. The in vivo assay (biodistribution/tissue deposition) has been performed using radiolabeled PLA/PVA NPs.

RESULTS

The nanoparticles produced showed a mean diameter of about 259 nm with a spherical shape. The in-vitro photodynamic therapy tests demonstrated that the combination is critical to enhance the therapeutic efficacy and it is dose dependent. The in vitro cell toxicity assay using endothelial cells demonstrated that the drug encapsulated into nanoparticles had no significant toxicity compared to control samples. In-vivo results demonstrated that the drug loading affects the biodistribution of the nanoparticle formulations (NPs). Low accumulation of the NPs into the stomach, heart, brain, and kidneys suggested that common side effects of Dacarbazine could be reduced.

CONCLUSION

This work reports a robust nanoparticle formulation with the objective to leveraging the synergistic effects of chemo and photodynamic therapies to potentially suppressing the drug resistance and reducing side effects associated with Dacarbazine. The data corroborates that the dual encapsulated NPs showed better in-vitro efficacy when compared with the both compounds alone. The results support the need to have a dual modality NP formulation for melanoma therapy by combining chemotherapy and photodynamic therapy.

Influence of the Exposome on Skin Cancer

Skin cancer is the most frequent type of cancer in humans. While exposure to solar radiation is the most widely known and relevant causal factor, the different degrees of individual risk have not been fully elucidated. Epidemiological studies show how the risk of skin cancer is affected by other types of radiation (eg, ionizing radiation), pesticides, particulate matter in air pollution, toxins (eg, arsenic) in water and some foods. Some living entities, such as polyomavirus and human papillomavirus, can also cause specific types of cancer. Lastly, lifestyle factors such as stress, sleep, and exercise may play a role, although only a few studies shed light on these factors. The abovementioned factors make up the exposome of skin cancer, that is, the set of environmental exposures that, together with the genome and microbiome, determine the onset of disease.

Combined lifestyle factors, incident cancer, and cancer mortality: a systematic review and meta-analysis of prospective cohort studies

Background

Cancer poses a huge disease burden, which could be reduced by adopting healthy lifestyles mainly composed of healthy diet, body weight, physical activity, limited alcohol consumption, and avoidance of smoking. However, no systematic review has summarised the relations of combined lifestyle factors with cancer morbidity and mortality.

Methods

EMBASE and PubMed were searched up to April 2019. Cohort studies investigating the association of combined lifestyle factors with risks of incident cancer and cancer mortality were selected. Summary hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using random-effects models. Heterogeneity and publication bias tests were conducted.

Results

The HRs (95% CIs) comparing individuals with the healthiest versus the least healthy lifestyles were 0.71 (0.66–0.76; 16 studies with 1.9 million participants) for incident cancer and 0.48 (0.42–0.54; 30 studies with 1.8 million participants) for cancer mortality. Adopting the healthiest lifestyles was also associated with 17 to 58% lower risks of bladder, breast, colon, endometrial, oesophageal, kidney, liver, lung, rectal, and gastric cancer. The relations were largely consistent and significant among participants with different characteristics in the subgroup analyses.

Conclusions

Adopting healthy lifestyles is associated with substantial risk reduction in cancer morbidity and mortality, and thus should be given priority for cancer prevention.

Dietary cadmium intake and risk of cutaneous melanoma: An Italian population-based case-control study

INTRODUCTION

Exposure to the heavy metal cadmium has been associated with many adverse health effects, such as atherosclerosis, diabetes, and cancer, possibly melanoma. In non-occupationally exposed individuals, food intake is a major source of cadmium exposure, after smoking. We aimed to assess the risk of melanoma in relation to dietary cadmium intake.

METHODS

Using a population-based case-control study design, we recruited 380 incident cases of newly-diagnosed cutaneous melanoma and 719 matched controls in the Emilia-Romagna Region, Northern Italy in the years 2005-2006. We evaluated dietary intake using a semi-quantitative food frequency questionnaire. We used conditional logistic regression to compute odds ratios (ORs) and 95% confidence intervals (CIs) for melanoma according to quintiles of dietary cadmium intake, adjusting for several potential confounders, and we modeled the association non-parametrically, using restricted cubic splines.

RESULTS

Median energy-adjusted intake of cadmium was 6.11 μg/day (interquartile range 5.38-6.91) among cases and 5.97 μg/day (5.15-6.79) among controls. For each 1 μg/day-increase in cadmium intake, the OR for melanoma was 1.11 (95% CI 1.00-1.24). Melanoma risk generally increased with increasing quintile of cadmium exposure, with ORs of 1.55 (95% CI 0.99-2.42), 1.54 (95% CI 0.99-2-40), 1.75 (95% CI 1.12-2.75), and 1.65 (95% CI 1.05-2.61) for the second through fifth quintiles, compared with the lowest quintile. Sex-stratified analysis showed ORs per 1 μg/day-increase in cadmium intake of 1.10 (95% CI 0.93-1-29) among men and 1.15 (95% CI 0.99-1.33) among women. Using spline regression analysis, we observed a generally linear increase in melanoma risk up to 6 μg/day of cadmium intake, after which the risk appeared to plateau.

CONCLUSIONS

We observed a positive non-linear association between dietary cadmium intake and risk of cutaneous melanoma in a Northern Italy population. However, further studies are needed to elucidate this association, due to concerns about exposure misclassification, unmeasured confounding, and the limited and conflicting evidence from epidemiological findings.