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1st February 2023
US and Taiwanese researchers have shown that the use of a single low-dose computed tomography (CT) scan, together with a deep learning algorithm, allows for a prediction of an individual’s risk of lung cancer over the next 6 years.
The use of low-dose CT screening has been shown to reduce mortality from lung cancer. Such screening allows for the early detection of the disease and hence the potential for better patient outcomes, although it has been suggested that the current screening guidelines might overlook vulnerable populations with a disproportionate lung cancer burden. Nevertheless, the efficiency of lung cancer screening could be improved by individualising the assessment of future cancer risk. The problem is determining how this can achieved. To date, there are some data to support the use of clinical risk assessment models that incorporate various factors compared to simply using age and cumulative smoking exposure. However, there are enormous possibilities created by greater use of artificial intelligence and deep learning models. In fact, it has become possible to utilise low-dose CT scan results and the presence of pulmonary nodules, into a model and to therefore optimise the screening process. But how useful are other pieces of information gathered from a CT scan beyond the presence of nodules, and could this other information be used by a deep learning model to predict future cancer risk.
This was the aim of the current study in which researchers developed a model, which they termed ‘Sybil’ using the entire volumetric low-dose CT data, without clinical and demographic information, to predict an individual’s future cancer risk. Sybil was able to run in the background of a radiology reading station and did not require annotation by a radiologist. The model was validated using information from three independent screening datasets which included individuals who were non-smokers.
Low-dose CT screening and lung cancer risk prediction
In total, data were retrieved from over 27,000 patients held in three separate databases. Sybil achieved an area under the curve (AUC) of 0.92, 0.86 and 0.94, for the 1-year prediction of lung cancer for each of these datasets. In addition, the concordance indices over 6 years were 0.75, 0.81 and 0.80 for the same three data sets.
The authors concluded that Sybil was able to accurately predict individual’s future risk of lung cancer based on a single low-dose CT scan and called for further studies to better understand Sybil’s clinical application.
Citation
Mikheal PG et al. Sybil: a validated Deep learning model to predict future lung cancer risk from a single low-dose chest computed tomography. Clin Oncol 2023
26th January 2023
Regular use of the herbicide glyphosate among farmers is associated with higher urinary levels of oxidative stress biomarkers, a key characteristic of carcinogens, according to US researchers.
Glyphosate appears to be one of the most widely used herbicides across the world. However, in 2015, the International Agency for Research on Cancer, deemed glyphosate as ‘probably carcinogenic to humans’ based on sufficient evidence derived from animal studies. Despite this assertion, the evidence derived from human studies is mixed. For example, a 2016 systemic review was unable to detect a causal relationship between use of the herbicide and lymphohematopoietic cancer. In contrast, a more recent, 2019 meta-analysis concluded that the findings from both experimental and mechanistic studies suggested a compelling link between the use of glyphosate-based herbicides and non-Hodgkin lymphoma. Moreover, while several in vitro studies indicate the the toxicological effects of glyphosate may occur through the induction of oxidative stress, the evidence from actual human studies is limited.
In the present study, the US team matched US farmers who self-reported use of glyphosate with non-farmers, with no history of cancer of exposure to pesticides within the last 10 years. Enrolled participates provided a first morning urine sample and were asked about use of specific pesticides in the last 12 months. Urinary concentrations of glyphosate and three oxidative stress biomarkers, 8-OHdG, 8-isoprostane and MDA were made and regression analysis performed after adjustments for age, lifestyle and medical factors.
Glyphosate and relationship with oxidative stress biomarkers
A total of 268 males with a mean age of 63.4 (100 of whom served as non-farming controls) were included in the analysis.
The highest quartile of glyphosate urinary concentration was significantly associated with the highest levels of 8-OHdG (geometric mean ratio, GMR = 1.15, 95% CI 1.03 – 1.28) and for MDA (GMR = 1.20, 95% CI 1.03 – 1.40) but not for 8-isoprostane.
Among farmers exposed to the herbicide within 1 day (compared to 5 to 7 days) of urine collection, there was also an association with both 8-OHdG (GMR = 1.20, 95% CI 1.01 – 1.42) and MDA (GMR = 1.28).
The authors suggested that since 8-OHdG reflects oxidative stress-induced DNA damage, their findings support the genotoxic potential of the herbicide.
They concluded that these findings may inform evaluations of the carcinogenic potential of the herbicide.
Citation
Chang VC et al. Glyphosate Exposure and Urinary Oxidative Stress Biomarkers in the Agricultural Health Study. J Natl Cancer Inst 2023.
27th October 2022
Patients who take up an invite for screening colonoscopy have a significantly reduced risk of developing colorectal cancer after 10 years according to the findings of a randomised trial by the NordICC study group.
In 2020, the World Health Organisation estimated that globally, there were 1.93 million cases of colorectal cancer and which resulted in 916,000 deaths. There are a variety of tests available for colorectal cancer screening and to date only the guaiac-based faecal occult blood test and sigmoidoscopy have been shown to reduce the incidence of colorectal cancer and its associated mortality in randomised trials. In addition to sigmoidoscopy, another endoscopic method is screening colonoscopy and which is considered to be the gold standard tool with a high sensitivity and specificity. However, to date, there are no large-scale randomised trials comparing the effectiveness of screening colonoscopy compared to no screening, to determine whether this impacts on the incidence of colorectal cancer.
In the present study, researchers created the Northern-European Initiative on Colorectal Cancer (NordICC) trial, which was a randomised trial investigating the effect of colonoscopy on colorectal cancer incidence and mortality. The trial enrolled individuals aged 55 to 64 who had not undergone previous screening and were randomised 1:2 to either an invitation to undergo screening colonoscopy or no invitation. The primary endpoint of the trial were the risks of colorectal cancer and death from the cancer after a 10 to 15 years, whereas the secondary endpoint was death from any cause.
Screening colonoscopy and cancer outcomes
A total of 84,585 individuals with a median age of 59 years (49.8% female) were enrolled, 28,220 of whom were invited for screening and who were followed-up for a median of 10 years. However, only 11,842 (42%) of participants accepted the invite and underwent screening.
The risk of colorectal cancer at 10 years was 0.98% in the invited group and 1.2% in the usual care (i.e., non-invited group), which was associated with an 18% lower risk of cancer (Risk ratio, RR = 0.82, 95% CI 0.70 – 0.93). However, the risk of colorectal cancer-related death was not significantly different between the groups (RR = 0.90, 95% CI 0.64 – 1.16). In addition, during the follow-up period, there was a similar level of death (11%) from any cause, in both groups.
The above data related to those who responded to the invite for screening but when researchers undertook a per-protocol analysis, i.e., assuming that all invitees underwent screening, the results were even more impressive. The risk of colorectal cancer at 10 years was reduced even further (RR = 0.69, 95% CI 0.55 – 0.83) as was the risk of colorectal cancer death (RR – 0.50, 95% CI 0.27 – 0.77).
The authors concluded that inviting patients for screening colonoscopy reduced the 10-year risk of colorectal cancer compared to those who were not screened.
Citation
Bretthauer M et al. Effect of Colonoscopy Screening on Risks of Colorectal Cancer and Related Death N Eng J Med 2022
22nd August 2022
A study has identified a higher male cancer risk in 19 out of 21 different cancers at shared anatomical sites which is only partially explained by known risk factors, underscoring the importance of sex-related biological features according to a study by a team of US researchers.
Cancer is a leading worldwide cause of deaths and which, according to the World Health Organisation, in 2020, was responsible for nearly one in six deaths. It is already recognised that there are sex-related differences in both the incidence and mortality from cancer. For example, the cancer incidence rate is 20% higher in men than in women though the male cancer death rate is 40% higher. Moreover, the reasons behind this disparity remain to be determined although traditional risk factor such as smoking and alcohol intake are clearly important. In fact, one European study found that smoking-related deaths accounted for around 40% to 60% of the gender gap and alcohol-related mortality for 20% to 30% in Eastern Europe and 10% to 20% elsewhere in Europe.
In an attempt to better understand the reasons for these sex-related differences in cancer, the US team estimated the risk for 21 solid tumours at shared anatomical sites and examined whether the higher male cancer incidence could be explained by known risk factors, such as smoking, diet, physical activity and alcohol use. They used data from the National Institutes of Health Diet and Health Study which began in 1995 and where a baseline questionnaire, asking about a wide range of issues including demographics, health status, co-morbidities and various lifestyle measures e.g., physical activity, levels of smoking, was mailed to over 3.5 million individuals aged 50 – 71 years of age. For the current study, the US team restricted their analysis to a smaller cohort who had completed both the baseline and follow-up questionnaire between 1996 and 1997. The main aim of the research was to estimate both crude and covariate adjusted male-to-female risk ratios of cancer incidence and to determine the extent to which these covariates and risk factors could account for the sex-related disparity in cancer risk.
Male cancer incidence and cancer disparities
The cohort included a total of 294,100 individuals with a median age of 63.5 years (41.7% female) with a mean of 11.5 person-years follow-up for men and 12.4 person-years for women.
Cancer incidence was recorded for 21 cancers and the biggest difference in the male-female incidence risk ratio (IRR) was for oesophageal adenocarcinoma (IRR = 12.19, 95% CI 8.32 – 17.86) and for gastric cardia cancer (IRR = 4.93, 95% CI 3.59 – 6.77). In fact, only thyroid and gall bladder cancer were more common in women than men.
After adjustment for covariates, oesophageal adenocarcinoma remained more common in men (Hazard ratio, HR = 10.80, 95% CI 7.33 – 15.90) as did gastric cardia cancer (HR = 3.49). Overall and after adjustment, the higher risk for men remained for 11 of the cancers.
When examining the effect of known risk factors, among 7 cancers (lung, colon, rectum, other biliary tract, skin, bladder and oesophageal adenocarcinoma), the distribution of risk factors and covariates explained some of the observed differences, ranging from 11.2% (oesophageal adenocarcinoma) to 49.4% (lung cancer). After adjusting for alcohol use, smoking status, body mass index and age groups, there was still no significant interaction effect for any of the cancer sites.
The authors concluded that sex-related biological factors appeared to represent major determinants of cancer incidence. The added that further analysis of physiologic, immunologic and genetic or genomic factors are needed across a wider range of cancers to better understand their contribution to the higher male cancer burden.
Citation
Jackson SS et al. Sex disparities in the incidence of 21 cancer types: Quantification of the contribution of risk factors Cancer 2022
4th August 2022
Daily insulin use increases the risk of developing cancer in patients with type 1 diabetes, with a greater risk among those who use a higher daily dose, according to findings of a study by US and Greek researchers.
Although diabetes and cancer are two heterogeneous, multifactorial, and chronic diseases, there are some epidemiological data indicating a higher risk of several types of cancer (including pancreas, liver, breast, colorectal, urinary tract, and female reproductive organs) in diabetic patients. Moreover, in an analysis of diabetic registries that specifically focused on patients with type 1 diabetes, a higher cancer risk was also identified for several types of cancer. However, whether this observed link is causal remains unclear. For example, in a 2016 meta-analysis of 16 observational studies in type 1 diabetics who used long-acting daily insulin, 13 studies reported no association between insulin glargine and detemir and any cancer and 4 studies reported an increased risk of breast cancer with insulin glargine. The authors concluded that observational studies examining the risk of cancer associated with long-acting insulin analogues have important methodological shortcomings that limit the conclusions that can be drawn. Nevertheless, whilst it is possible that the presence of type 1 diabetes is linked to an increased risk of cancer, no studies have examined potential patient risk factors. Consequently, for the present study, researchers turned to data from the Diabetes Control and Complications trial (DCCT) and the Epidemiology of Diabetes Interventions and Complications study (EDIC) to gain a better understanding of which, if any, factors increased the risk of cancer.
The DCCT enrolled patients between 1983 and 1989 and when the trial was completed in 1993, 1375 survivors continued in the EDIC study and follow-up data was available for 28 years. Daily insulin dose was categorised as low (< 0.5 units/kg), medium (> 0.5 and < 0.8 units/kg) and high (> 0.8 units/kg). The researchers used multivariable models to assess the association between several different factors and cancer incidence.
Daily insulin and cancer
Among a total of 1303 patients who were followed-up for 33,813 person-years, 93 (7%) developed cancer, giving an incidence rate of 2.8 (95% CI 2.2 – 3.3) per 1000 person-years. The mean age of participants at their cancer diagnosis was 50 years and the mean duration of diabetes was 25 years. Among the 93 who developed cancer, 61% were female. The majority of individuals (58%) developed their cancer after 21 and 28 years and the cancers affected the skin (27), breast (15) and digestive tract (6).
Factors associated with the development of cancer were age (hazard ratio, HR = 1.08, 95% CI 1.05 – 1.12) and female gender (HR = 1.74, 95% CI 1.15 – 2.64). Interestingly, participation moderate or strenuous exercise was associated with a reduced risk of cancer (HR = 0.31, 95% CI 0.16 – 0.59, p = 0.001).
In multivariable models, daily insulin use was associated with a 4-fold higher risk of cancer (HR = 4.13, 95% CI 1.13 – 15.17, p = 0.03). The cancer incidence was 2.11, 2.87 and 2.91 per 1000 person-years in the low, medium and high-dose daily insulin groups respectively.
Although the previous 2016 meta-analysis described earlier did not derive a clear association between type 1 diabetes and cancer, the authors of the current study suggested that this was because in the cohorts examined the doses of insulin used were low (< 0.3 units/kg) and many had discontinued treatment during follow-up.
The authors also felt that their observations may have been due to residual confounding and that potentially, the associations may not have been causal. They called for further studies to validate this association.
Citation
Zhong W, Moa Y. Daily Insulin Dose and Cancer Risk Among Patients With Type 1 Diabetes JAMA Oncol 2022
1st July 2022
Patient who have undergone bariatric surgery have a significantly lower risk of developing an obesity-related cancer as well as cancer-related mortality. This was the conclusion of a cohort study by a team of US researchers.
Individuals with a body mass index (BMI) above 25 are considered to be overweight but when the BMI exceeds 30, these individuals are deemed to be obese. Data from the World Health Organisation suggest that in 2016, 1.9 billion adults across the world were classed as overweight and 650 million obese. Although obesity increases the risk of cardiovascular disease, obesity has also been found to be associated with greater overall mortality in patients with cancer.
Whilst dieting helps many people to lose weight, one of the most effective weight loss strategies is surgery and in one follow-up study after a Roux-en-Y gastric bypass, the mean weight loss change from baseline was 35 kg at 12 years. Given the elevated risk of certain cancers in those who are obese, could weight loss reduce the risk of subsequently developing an obesity-related cancer? Unfortunately, the evidence base supporting this premise is limited apart from one study in patients who underwent bariatric surgery and which found that after a mean follow-up of 12.5 years, total cancer incidence was significantly lower in the surgical group compared to controls. Nevertheless, a limitation of the study was the absence of a matched control group, particularly in relation to possible cancer risk factors such as smoking history.
Consequently, there remains some uncertainty over whether weight loss can reduce the risk of cancer and this was the basis for the current study. The US team undertook the Surgical Procedures and Long-term Effectiveness in Neoplastic Disease Incidence and Death (SPLENDID) trial, which was a retrospective, observational, matched, cohort study in adults with obesity who either underwent bariatric surgery or who received usual care (i.e., no surgery). Participants were included if they had a BMI of between 35 and 80 and underwent either Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG). The primary endpoint of the study was the first occurrence of 1 of 13 types of obesity-associated cancers including oesophageal adenocarcinoma, renal cell carcinoma, colon, rectum, liver and pancreatic cancer. As a secondary endpoint, the team considered the incidence of all types of cancer and cancer-related mortality.
Bariatric surgery and cancer development
A total of 30,318 patients with a median age of 46 years (77% female) including 5,053 who underwent bariatric surgery, (RYGB 66%) were included in the analysis. After 10 years, participants in the bariatric surgery group had lost 27.5 kg compared to 2.7 kg in the control group (p <0.001).
During the period of follow-up, 96 patients in the bariatric surgery group and 780 in the control group developed one of the obesity-related cancers, giving an incidence rate of 3 vs 4.6 events (surgery vs control) per 1000 person-years.
The cumulative incidence of the primary endpoint at 10 years was 2.9% in the surgery group and 4.9% in the non-surgical (control group) and which was statistically significant (hazard ratio, HR = 0.68, 95% CI 0.53 – 0.87, p = 0.02). In addition, the cumulative incidence of cancer-related mortality at 10 years was 0.8% in the surgical group compared to 1.4% in the control group and which again, as statistically significant (HR = 0.52, 95% CI 0.31 – 0.88, p = 0.01).
Based on these findings, the authors concluded that bariatric surgery is associated with a significantly lower incidence of obesity-associated cancer and cancer-related mortality.
Citation
Aminian A et al. Association of Bariatric Surgery With Cancer Risk and Mortality in Adults With Obesity JAMA 2022
13th May 2022
Cancer is the second leading cause of death globally and in 2018, it accounted for approximately 9.6 million deaths. Although cancer can strike at any age, many types of cancer become more prevalent with increasing age. However, recent research has found that for most adults, cancer does not have to be an inevitable consequence of growing older. In fact, adoption of healthy lifestyle measures based on a combination of exercise, diet, smoking status, alcohol consumption, and anthropometry, in other words, simple behavioural modifications, have been shown to produce a sizeable reduction in the risk of some cancers. Among healthy interventions, there is evidence that physical activity is associated with a lower risk of several cancers. Equally, use of vitamin D supplements has some evidence to support its use in reducing the incidence of advanced (metastatic or fatal) cancer. Finally, an omega-3 fatty acid-rich diet, can significantly delay mouse tumour growth when compared with a monounsaturated fatty acid-rich diet. Nevertheless, whether a combination of exercise, vitamin D and omega-3 fatty acids provides a synergistic and preventative effect against cancer is less clear.
For the present study, the researchers undertook a randomised controlled trial, which sought to examine the combination of exercise, supplementation with vitamin D and omega-3 fatty acids in older adults and how this impacted on the subsequent development of cancer. Their DO-HEALTH trial examined the combined effect of simple home strength exercise (SHEP), vitamin D (2000 IU/day) and/or 1g/day of marine omega-3 fatty acids, in healthy adults 70 years of age and older. For the primary outcome, the team considered the time to the development of a verified invasive cancer.
Combination of exercise, omega-3 fatty acids, vitamin D and cancer development
A total of 2157 individuals with a mean age of 74.9 years (61.7% female) were included in the study and followed for a median of 2.99 years. During this period of time there were 81 invasive cancers diagnosed and verified.
For the three separate interventions, the adjusted hazard ratios (compared to controls) were 0.76 (95% CI 0.49 – 1.18) for vitamin D, 0.70 (95% CI 0.44 – 1.09) for omega-3 fatty acids and 0.74 (95% CI 0.48 – 1.15) for SHEP). In other words, while there were beneficial effects from the individual interventions, the effects were not statistically significant, but when two of the interventions were combined, the effect did become statistically significant. For instance, the combination of SHEP and omega-3 resulted in an adjusted hazard ratio of 0.52 (95% CI 0.28 – 0.97, p = 0.039). However, the greatest benefit was derived from the combination of exercise, vitamin D and omega-3 fatty acids, with an adjusted hazard ratio of 0.39 (95% CI 0.18 – 0.85, p = 0.017).
The authors calculated that the number needed to treat to prevent one incident case of cancer after three years with the three treatments combined was 35.
They concluded that future studies should focus on the benefit of combining interventions as a means of cancer prevention.
Citation
Bischoff-Ferrari HA et al. Combined Vitamin D, Omega-3 Fatty Acids, and a Simple Home Exercise Program May Reduce Cancer Risk Among Active Adults Aged 70 and Older: A Randomized Clinical Trial Am J Clin Nutr 2022
12th May 2022
A higher level of dairy consumption in Chinese adults has been found to be linked to an increased overall risk of developing cancer and in particular, liver and female breast cancers. This was the key finding of a prospective study by researchers from the UK and China.
Across the globe in 2020, it has been estimated that cancer was responsible for an estimated 19.3 million new cases and almost 10.0 million cancer deaths. Several dietary factors are linked with a reduced risk of developing cancer, including for example, a higher intake of fruit and vegetables, which is associated with a 17% lower cancer mortality. Another food linked with cancer is dairy products and a higher dairy consumption lowers the risk of developing colorectal cancer. However, intake of egg, fish and dairy consumption has remained at a low level among Chinese people with other work finding that dairy consumption was seriously inadequate in Chinese elderly and appears to be reducing. As a result, for the present study, researchers were interested in determining if, despite low levels of intake among the Chinese (compared to Westernised countries), dairy intake was associated with the incidence of cancer.
Turning to data held within the China Kadoorie Biobank, which represents a population-based prospective analysis with over 0.5 million adults across China, the researchers obtained information on the frequency of dairy consumption and which was categorised as daily, 4 – 6 day/week, 1 – 3 days/week, monthly or never/ready and which served as a baseline. The information on dairy intake was re-collected at two follow-up surveys and used to estimate mean intake of dairy foods. Cox regression analysis was used to link incident cancers with dairy consumption and adjusted for several covariates including a family history of cancer, alcohol intake and levels of smoking.
Dairy consumption and incident cancer
Among a population of 510,146 individuals with a mean age of 52 years (59% women), 20.4% reported intake of dairy foods at least once a week (subsequently referred to as ‘regular dairy consumers’) and which was largely for milk. Participants were followed for a mean of 10.8 years, during which time there were 29,277 incident cancer cases recorded. In the fully adjusted models, each 50g/day increase in dairy consumption was associated with a 7% increased risk of total cancer (hazard ratio, HR = 1.07, 95% CI 1.04 – 1.11) when compared to those who never consumed dairy foods. Furthermore, among regular dairy consumers, there was a significant increased risk of liver cancer (HR = 1.12, 95% CI 1.02 – 1.22) and for female breast cancer (HR = 1.17, 95% CI 1.07 – 1.29). There was no significant association for any other form of cancer including colorectal cancer.
The authors concluded that higher dairy consumption was associated with a greater risk of cancer among Chinese individuals even though levels of dairy intake are low compared to Westernised countries.
Citation
Kakkoura MG et al. Dairy consumption and risks of total and site-specific cancers in Chinese adults: an 11-year prospective study of 0.5 million people. BMC Med 2022
30th March 2022
The consumption of foods and beverages which contain artificial sweeteners has been found to be associated with a slight increased risk of cancer according to the results of a large, French cohort study by researchers from the Sorbonne Paris Nord University, University of Paris, France.
The World Health Organization recommends that both adults and children should reduce their intake of free sugars to less than 10% of total energy intake. Consequently, manufacturers developed alternatives to sugar and artificial sweeteners were developed, one of which is aspartame, that has been used since 1981 and is present in more than 6,000 products. Although aspartame contains the same number of calories as sugar, it is around 200 times sweeter than sugar. The potential carcinogenicity of artificial sweeteners like aspartame has always been controversial and one review in 2014 suggested that the studies performed in the 1970s did not provide adequate scientific support for the safety of aspartame and that more recent life-span carcinogenicity data undertaken with rodents provide consistent evidence of aspartame’s carcinogenic potential. Moreover, a 2021 review of aspartame and cancer concluded that new findings confirm that aspartame is a chemical carcinogen in rodents. Nevertheless, it has been unclear from studies in humans whether artificial sweeteners are associated with an increased risk of cancer. For example, one 2012 prospective study that evaluated whether the consumption of aspartame- and sugar-containing soda is associated with risk of haematopoietic cancers, concluded that the apparent cancer risk in individuals who consume regular soda do not permit the ruling out of chance as an explanation. In contrast, a second study concluded that higher levels of aspartame intake were not associated with the risk of overall hematopoietic cancer.
With some uncertainty over the association between cancer and intake of artificial sweeteners, for the present study, the French team prospectively followed participants in the NutriNet-Sante study. This prospective trial was designed to determine, among adults, any associations between nutrition and health. Nutritional intake information is collected at baseline and every year on various factors such as health status, physical activity, smoking status and diet using 24-hour dietary recall questionnaires through which the intake of artificial sweeteners can be assessed.
Artificial sweeteners and cancer risk
A total of 102,865 participants with a baseline mean age of 42.2 years (78.5% female) were followed for a median of 7.8 years and consumption of artificial sweeteners was recorded for 36.9% of participants.
A total of 3,358 incident cancers developed during the follow-up period. Compared those who did not consume artificial sweeteners, among high consumers, there was an increased risk of cancer development (hazard ratio, HR = 1.13, 95% CI 1.03 – 1.25, p-trend = 0.002). Two sweeteners in particular, aspartame (HR = 1.15, p = 0.002) and acesulfame-K (HR = 1.13, p = 0.007) were associated with higher cancer risks. In addition, aspartame was associated with an increased risk of breast cancer (HR = 1.22, 95% CI 1.01 – 1.48, p = 0.036).
Based on these findings, the authors concluded that while the study could not establish causal links, their findings did not support the use of artificial sweeteners as a safe alternative to sugar in food and beverages.
Citation
Debras C et al. Artificial sweeteners and cancer risk: Results from the NutriNet-Santé population-based cohort study PLoS Med 2022
21st March 2022
Individuals who are regular meat eaters have been found to be at a higher risk of all and some specific cancers compared to those who are either low meat eaters, pescatarians or vegetarians. This was the finding of a study of the UK Biobank database by researchers from the Cancer Epidemiology Unit, University of Oxford, Oxford, UK.
Cancer has been declared by the World Health Organization (WHO) as a leading cause of death worldwide accounting for nearly one in six of all deaths (10 million in 2020). Moreover, according to WHO, breast, lung, colorectal and prostate cancers are the most common forms of the disease. Understanding the causal relationship between dietary patterns or even particular dietary components and cancer aetiology and prevention is a challenge. For example, undertaking randomised controlled intervention trials to examine the association between diet and cancer outcomes are not feasible, for a number of reasons including cost, the difficulty of ensuring compliance among control and intervention groups as well as the long time-frame and exposure necessary to affect the carcinogenesis process. Although it has been shown that the risk of some cancers is lower in fish eaters and vegetarians than in meat eaters, it is not universally true with other work showing no statistically significant associations with dietary pattern and risk of premenopausal breast cancer.
For the present analysis, the Oxford team examined the relationship between those who ate meat at least 5 times a week, low meat consumers (< 5 times/week), pescatarians and vegetarians and the risk of all cancers and in particular, colorectal, postmenopausal breast and prostate cancers. They used data held in the UK Biobank and excluded individuals with a cancer diagnosis at recruitment. Participants completed an online questionnaire at recruitment into the database which asked about consumption and frequency of meat intake. The team also assessed whether specific hormones such as insulin-like growth factor-1 and testosterone as well as body mass index, might have potential mediator effects on the association between dietary patterns and cancer risk. The risks for the development of all and any of the specific cancers, were assessed using meat eaters as the reference group.
Meat eaters and cancer risk
A total of 247,571 individuals with a mean age of 56 years (46.4% female) were classed as meat eaters, 205,385 as low-meat eaters, 10,696 as pescatarians and 8,685 as vegetarians. After an average follow-up of 11.4 years, 54,861 incidence cases of cancer occurred; 5882 colorectal, 7537 women with postmenopausal breast cancer, 9501 men with prostate cancer.
After adjustment for several factors such as smoking status, physical activity etc, a vegetarian diet was associated with a 14% lower risk of all cancers compared to the reference group. (hazard ratio, HR = 0.86, 95% CI 0.80 – 0.93). This risk was also significantly reduced for breast cancer (HR = 0.82) and prostate cancer (HR = 0.69).
For pescatarians, there was also a lower risk of all cancers (HR = 0.90) compared to the reference meat group and for prostate cancer (HR = 0.80). For those categorised as low-meat eaters, the risks were only significantly lower for colorectal cancer (HR = 0.91).
After adjustment for possible mediators, only body mass index was found to be relevant and the risk of all cancers was slightly attenuated for vegetarians (HR = 0.88) and pescatarians (HR = 0.92) but remained significant. Furthermore, the reduced cancer risk remained significant among pescatarians and vegetarians but only for prostate cancer.
The authors concluded that being a pescatarian or vegetarian was associated with a lower risk of all cancers and that this might be attributable to differences in dietary factors in comparison to those who regularly eat meat. However, they added that it was unclear if these associations are causal or due to residual confounding, i.e., due to other, but unmeasured factors.
Citation
Watling CZ et al. Risk of cancer in regular and low meat-eaters, fish-eaters, and vegetarians: a prospective analysis of UK Biobank participants BMC Med 2022
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