How Does Cancer Research Uk Evaluate Evidence
We regularly review new research on the causes of cancer to make sure our information is up to date and based on the best quality evidence. We develop our information by looking at lots of research carried out over many years. So, although new research comes out all the time, it is unlikely that one new study would change our position on a topic.
Some studies are better than others at telling us about how different factors affect cancer risk. These are some of the things we consider:
- Did the study look at cells, animals or people?
Studies in animals and cells can help scientists understand how cancer works, but they cant always tell us how its relevant to humans. So we focus on studies in people.
- How big is the study and how long did it go on for?
Studies on small numbers of people arent as reliable, because results are more likely to happen by chance. And studies that only follow people for a short amount of time can miss long-term effects. So we mainly look at studies that follow thousands of people over many years.
- Did the study account for other factors that could affect someones cancer risk?
There are lots of factors that can affect someones risk of cancer. Studies should take known risk factors into account. For example, if a study is looking at air pollution and lung cancer, it should also look at whether participants smoked.
- Where is the study published and who funded it?
How to find accurate information on cancer
Why Breathing Wildfire Smoke Is Dangerous
Protecting yourself starts with understanding exactly why breathing wildfire smoke is harmful, says Jing Gennie Wang, MD, pulmonologist and assistant professor of pulmonary, critical care, and sleep medicine at The Ohio State University Wexner Medical Center.
Wildfire smoke is a type of air pollution and scientists define the extent of air pollution by measuring levels of toxic particulates. There are two main concerns with wildfire smoke, Dr. Wang says. First are the variety of toxic compounds based on what has been burned for instance, you will find plastic, lead, heavy metals, and other toxins from burning buildings. Second are particulates. Larger particles of dust, dirt, and smoke can irritate eyes, skin, and throat but fine particles, those smaller than 2.5 m in diameter, known as particulate matter , are even more dangerous as they get deposited deep within the lungs and can even enter the bloodstream.
The closer you are to the fires, the more of these pollutants you are exposed to. In Napa, California, scientists measured levels of PM2.5 nearly six times higher than the standard for air quality in the U.S. due to the nearby wildfire. Because the body has a hard time clearing fine particulates from your system, the effects can be cumulative over time. The more wildfire smoke you breathe, the worse the effects will be, she says.
Epigenetics In Lung Cancer And Copd
In addition to genetic changes, epigenetic changes including DNA methylation, covalent histone modifications, microRNAs expression and nucleosome remodeling have also been reported to play an important role in the development of cancer and COPD . DNA methylation, which is a reversible modification of DNA structure, adding a methyl group to the 5 position of a cytosine residue, often as part of a CpG island or cluster , of tumor suppressor genes including APC, CDKN2, BRCA1, Rb and MDM2 contributes to increased proliferation , . Hypermethylation of tumor suppressor and other gene promoters is observed in the majority of lung cancers . The reversible nature of promoter hypermethylation makes it an attractive target for cancer therapy.
Unsupervised hierarchical clustering of DNA methylation patterns results in 3 lung cancer clusters . Lung adenocarcinomas in Cluster 1 developed from an inflammatory background in COPD in heavy smokers and were locally invasive. Overall, DNA methylation profiles may reflect carcinogenetic factors such as smoking and COPD and may distinguish patients with distinct types of NSCLC.
Although alterations to DNA methylation have been examined in COPD these are mostly linked to hypomethylation of immune-modulatory genes or in the SERPINA1 gene coding for alpha1-antitrypsin and linked to gene overexpression.
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Possible Harms Of Marijuana
Smoked marijuana delivers THC and other cannabinoids to the body, but it also delivers harmful substances to users and those close by, including many of the same substances found in tobacco smoke.
Because marijuana plants come in different strains with different levels of active compounds, it can make each users experience very hard to predict. The effects can also differ based on how deeply and for how long the user inhales. Likewise, the effects of ingesting marijuana orally can vary between people. Also, some chronic users can develop an unhealthy dependence on marijuana.
Mental Health Effects On Caregivers And Family Members
Studies have shown that caregivers tend to experience stress, depression, lower life satisfaction, and poorer physical health when compared to non-caregivers. Family members and friends of the patient can also experience this, as these individuals are always around the lung cancer patient, potentially causing distress that can lead to a multitude of mental conditions. This condition is also known as caregiver and compassion fatigue and can also encompass problems focusing, decision making, sleeping, and eating. Burnout may also negatively impact employment, income, and other day-to-day situations if coping mechanisms arent developed.
If a caregiver is under too much stress and needs a break, they can seek the help of a hospice team. The hospice workers can provide the caregiver with a temporary leave while they take care of the lung cancer patient.
Caregivers and loved ones must also try to maintain self-care to avoid negative mental health effects associated with lung cancer, some methods involve:
Caring for someone with lung cancer? Try to maintain proper self-care while developing coping methods for difficult times. This will help fight compassion fatigue so that caregivers and loved ones can avoid burnout as long as possible.
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Genetic Predisposition To Lung Cancer And Copd
There is evidence for familial susceptibility in both COPD and lung cancer. This familial susceptibility appears to be linked and not just associated with the common consumption of cigarettes implying that the underlying genetic predisposition to both diseases may be the same or reflect the link between the immune system, inflammation and cancer . Linkage studies have implicated regions in chromosome 6 as being linked to both diseases , , . Furthermore, GWAS studies in large COPD and lung cancer cohorts have found the same risk loci including CHRNA3 and CHRNA5 SNPs and regions at 4q31 , 4q24 and 5q . Nicotine addiction may explain the overlap in risk loci between lung cancer, smoking behavior and COPD . Epithelial to mesenchymal transition and inflammation are pathogenic features of COPD and lung cancer and the rs7326277TT genotype in VEGFR1, which promotes inflammation, EMT and tumor growth, is a susceptible locus for both COPD and lung cancer . Several studies have demonstrated that polymorphisms in the anti-inflammatory gene IL10 are associated with increased rates of lung and other cancer , .
Oxidative Stress Damages Dna
The free radical hypothesis of aging proposes that RNOS drives the accumulation of cell and DNA damage and elevated levels of oxidative stress are seen in many cancers , , , , , , . Oxidative stress drives cancer initiation through DNA damage: point mutations, single stand breaks and double strand breaks and DNA cross-linking , , which if incorrectly repaired, results in mutations. The number of somatic mutations, which lead to cancer, accumulates with age in part due to continuous RNOS exposure. Hydroxyl radicals and peroxinitrate are especially implicated in DNA damage . RNOS can lead to the degradation of proteins, including tumor suppressors leading to cell division and decreasing apoptosis and DNA repair .
RNOS also plays a role in cancer promotion and progression . RNOS is an intracellular signal and activates proliferative and inflammatory pathways, including the c-Jun N-terminal kinases dependent mitogen activate protein kinase pathway which, in turn, drive proliferation . Growth factor signal transduction via RNOS is associated with oxidation of thiol groups of tyrosine phosphatases, which results in their reversible inactivation and facilitates proliferation . Additionally NO can increase angiogenesis through vascular endothelial growth factor stimulation and increases tumor growth and cell invasion properties .
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Wildfire Smoke And Lung Cancer Risk
Meteorologists are fond of comparing wildfire smoke inhalation to cigarette smoking as a way to demonstrate the ongoing risk to the public in their forecasts. This is not really a good comparison, our doctors say. “For starters, cigarettes are addicting and no one is out there intentionally or habitually breathing wildfire smoke,” Dr. Gerber says.
Dr. Wang points out that the chemical composition of wildfire and cigarette smoke is very different, with wildfire smoke not containing the harmful tobacco and other cancer-causing toxins found in cigarettes.
That doesn’t mean you’re in the clear when it comes to lung cancer or other cancers. There is no definitive research yet but that may be because there are so many variables involved. “Your cancer risk really comes from what’s burning, how much smoke you’ve inhaled, and how long you’ve been exposed to it,” Dr. Gerber says. “I think we will learn a lot more about this in the coming years.”
But How You Cope With Or Manage Stress Can Affect Your Health
Its very common to feel stressed, and its likely that everyone will feel stress at some point.
But people respond to stress in different ways. This can lead to changes in a persons day to day routine that can impact their cancer risk.
For some, stressful times can make it more difficult to be healthy. Remember, 4 in 10 cancer cases could be prevented. Things to think about include:
Do you only smoke, or smoke more when you are stressed? Remember, its never too late to get free stop smoking support.
Stress may change what and how much you eat. Having a healthy, balanced diet is a proven way to reduce cancer risk.
Do you drink alcohol when youre stressed or more than you usually would? Dont forget, the less alcohol you drink, the lower the risk of cancer.
Stress may affect how much you move or exercise during the day. But being more active can help to prevent cancer. What counts as exercise may surprise you.
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No Being Stressed Doesnt Directly Increase The Risk Of Cancer
The best quality studies have followed up many people for several years. They have found no evidence that those who are more stressed are more likely to get cancer.
Some people wonder whether stress causes breast cancer. But overall, the evidence for this has been poor. And a large study of over 100,000 women in the UK in 2016 showed no consistent evidence between stress and breast cancer.
Side Effects Of Cannabinoid Drugs
Like many other drugs, the prescription cannabinoids, dronabinol and nabilone, can cause side effects and complications.
Some people have trouble with increased heart rate, decreased blood pressure , dizziness or lightheadedness, and fainting. These drugs can cause drowsiness as well as mood changes or a feeling of being high that some people find uncomfortable. They can also worsen depression, mania, or other mental illness. Some patients taking nabilone in studies reported hallucinations. The drugs may increase some effects of sedatives, sleeping pills, or alcohol, such as sleepiness and poor coordination. Patients have also reported problems with dry mouth and trouble with recent memory.
Older patients may have more problems with side effects and are usually started on lower doses.
People who have had emotional illnesses, paranoia, or hallucinations may find their symptoms are worse when taking cannabinoid drugs.
Talk to your doctor about what you should expect when taking one of these drugs. Its a good idea to have someone with you when you first start taking one of these drugs and after any dose changes.
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Blame Epinephrine Not Cortisol
When they looked into how various physiological factors changed in the mice that had experienced chronic stress, the researchers closed in on a hormone called epinephrine.
The stressed mice had much higher levels of this hormone than the mice in the control group. Also, in mice from the experimental group that had received a drug that blocked ADRB2 which is an epinephrine receptor cancer tumors were smaller and the numbers of cancer stem cells were also lower.
When most people think of stress, says Kelley, they think its cortisol thats suppressing the immune system. However, he adds, The amazing thing is cortisol was actually lower after a month of stress.
How does epinephrine help cancer stem cells thrive? The authors explain that when this hormone binds to ADRB2, the interaction boosts levels of lactate dehydrogenase, an enzyme that normally gives muscles an injection of energy in a danger situation. This allows the person to either fight the threat or run away from it.
A byproduct of this energy boost is the production of an organic compound called lactate. In the case of people with cancer, the harmful cells actually feed on this compound it allows them to acquire more energy.
This means that if a person has chronic stress, they will have too much lactate dehydrogenase in their system. This, in turn, will activate genes related to cancer growth and allow cancer cells to thrive.
Important To Take Care Of Mental Wellbeing
Hrönn, who is passionate about improving the wellbeing and prognosis of all patients, says that this is a forward-thinking study of 130 patients who were diagnosed with lung cancer at Landspítali University Hospital between 2015 and 2018. She says that this doctoral project is an important contribution to research into the consequences of mental distress and the effect that emotions have on a person’s health.
“The findings may further reinforce the importance of looking after the mental wellbeing of patients in this situation as well as their physical health. We are looking at stress responses in patients diagnosed with lung cancer, their predictive factors and their impact on the development of the disease and survival rates. Data has been gathered on mental wellbeing, stress and the physiological manifestations of stress before and after the lung cancer diagnoses, as well as histopathological factors.”
Hrönn says that in order to provide appropriate support for this patient group, it is essential to acquire a better and deeper understanding of how patients feel and how stress can affect the progression of the disease.
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High Levels Of Stress Hormone May Reawaken Cancer Cells
The study, published in the journal Science Translational Medicine, found that when norepinephrine a stress hormone spikes in the body, it triggers a series of events. Researchers found that high levels of norepinephrine causes the activation of cells called neutrophils, which in turn release a special type of lipid that can reactivate dormant cancer tumours.
Because tumour recurrence can happen years after someones seemingly successful cancer treatment, researchers believe the reactivation of dormant cells is largely responsible for this phenomenon. Scientists have been trying to better understand the mechanisms that prompt cancers to return for years.
Stress and cancer
According to the Canadian Cancer Society , there is currently no proven, definite cause-and-effect relationship between stress and cancer. But theres plenty of evidence that psychological stress can affect your body and some studies suggest a link between various psychological factors and an increased risk of developing cancer.
Improving cancer care
There is even clinical trial going on where patients with melanoma are given propranolol in combination with check-point inhibitor pembrolizumab , Gabrilovich says. Authors reported minimal side effects and some encouraging clinical data. However, it was given only for short time and goal was to increase the effect of anti-PD1 antibody.
Stress And Cancer Risk
It’s tricky to design a study to show that stress fuels cancer in part because the experience of stress is so subjective and hard to measure. Stress can also manifest itself in the body in very different ways depending on how an individual perceives and copes with it, Toworoger said
“Some people have a negative response to job stress and some people love being stressed out in their jobs,” Tworoger said. In fact, “they thrive on it.” This perception, in turn, affects how the body responds.
As a result, many human studies rely on associations rather than cause and effect to show a link between stress levels and cancer incidence.
Previous studies have suggested, for example, that chronic stress is associated with an increased risk of a number of cancers, including breast cancer and some gastrointestinal cancers.
A Japanese study published in 2017 in the journal Scientific Reports looked at the correlation between stress levels and cancer in more than 100,000 people. They found no association between short-term stress and cancer incidence, but found that individuals, specifically men, who consistently had high-stress levels for a long time had an 11% greater risk of developing cancer than those with consistently low stress levels.
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What Are Symptoms Of Lung Cancer
Signs and symptoms of lung cancer can not be found before the disease has advanced. Advanced lung cancer symptoms include coughing/thawing short / short breath chest pains, fatigue and unintentional weight loss. Symptoms which may be seen when the cancer is spread to other places such as bone or blood drooping eyelids are the most common. Some people do have early signs of coughs or respiratory issues.
How Can I Manage Stress
Feeling stressed is normal, but long periods of stress have been linked to high blood pressure and depression. If youre struggling to cope with stress, its a good idea to speak to your doctor.
You can find information and tips about coping with stress on the NHS and Mind websites.
There are many cancer myths, including stress, that havent been proven to cause cancer. However, there are proven causes of cancer, and things you can do to reduce your risk.
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