The sooner we spot the symptoms of cancer, the sooner we can get it treated - but many of us delay seeking help when we sense something isn't right.
A recent poll showed around half of us Brits put off contacting a GP for up to six months after noticing red-flag cancer symptoms.
A survey by global public opinion and data company YouGov found that just under half the 2,468 people quizzed contacted their GP within half a year of experiencing serious symptoms such as unexplained weight loss and a new or unusual lump.
Dr Julie Sharp, Cancer Research UK’s head of health and patient involvement, said: “You might think of red flag symptoms like coughing up blood or unexplained bleeding as hard to ignore, but the research shows that many do".
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Teachers, civil servants and train drivers walk out in biggest strike in decadeThe charity says that spotting cancer at an early stage means treatment is more likely to be successful, so if you notice something that's not normal for you, talk to your GP.
So what are the red flag symptoms you should be keeping an eye out for?
Fatigue is something that affects us all, particularly with life being generally stressful for many of us at the moment. If you've been having trouble drifting off at night - and staying asleep - then it's perfectly normal to feel more tired than usual.
But if you have been sleeping well and still feel tired then this could be a sign that something isn't right. Having very little energy can be a symptom of blood cancers, such as lymphoma, leukaemia and multiple myeloma.
These cancers begin in the bone marrow - the soft, spongy tissue found in the centre of most bones - which produces red blood cells that carry oxygen throughout the body.
Cancer Research UK says it's normal to experience more pain the older we get. But any unexplained pain can be a sign that something more serious might be going on.
The charity says: "Pain is usually a sign that something is wrong. It is a sign that you have an illness or an injury. When there is damage to any part of your body, your nervous system sends a message along nerves to your brain. When your brain receives these messages, you feel pain. This includes pain caused by cancer".
The health organisation says it's important to remember that not all cancers cause pain.
"Many people with cancer do not have pain. This is because cancers don't have any nerves of their own. The pain comes from a tumour pressing on nerves nearby," it says.
The NHS says it's normal to sweat during the night if the room or your bedding is making you too hot. But night sweats are when you sweat so much that your night clothes and bedding are soaking wet - even though where you're sleeping is cool.
Greggs, Costa & Pret coffees have 'huge differences in caffeine', says reportNight sweats are common if you're going through the menopause, and it's also not unusual for infections or certain medications to send your temperature skywards.
But Cancer Research UK advises you see your GP if you have an unexplained fever or very heavy, drenching night sweats. Experts at healthline say that sweating at night is a less well-known symptom of certain types of cancers, including:
Bone cancer
Lymphoma
It is unclear why some types of cancer can cause night sweats. But healthline says it could be linked to the body trying to fight the cancer.
"Hormone level changes may also be a cause. When cancer causes a fever, your body may sweat excessively as it tries to cool down", it says.
Cancer Research says that any persistent lumps or swelling in any part of your body should be investigated. This includes any lumps in the groin, armpit, neck, stomach, chest, breast, or testicle.
Most, if not all, of us experience small changes in weight on a daily basis, and it's absolutely nothing to be concerned about. But if you notice you look thinner and haven't been trying to lose any weight, then it's sensible to flag this with your doctor.
Unusual weight loss was the second highest risk factor for bowel, lung, pancreatic and kidney cancers, revealed researchers from the University of Oxford.
Any bleeding or bruising when you haven't hurt yourself should always warrant a visit to your GP. This includes vaginal bleeding between periods, after sex or following the menopause, as well as blood in your urine or poo and vomiting or coughing up blood.
It is still worth investigating even if you don't feel like there is much blood, which can be red or a darker colour such as brown or black.
Usually, the first symptom of breast cancer is a lump in the breast or some thickening. A lump in your breast should always be investigated, but you should also be aware if they feel different, are a different size, or of any skin changes, redness, or pain.
The appearance of your nipple or how it feels could also change, and they could also leak fluid; this is something to watch for if you're not pregnant or breastfeeding.
Most of us have experienced a mouth ulcer. They're are a small sore that can emerge after feeling run-down.
They usually disappear within a fortnight, but if an ulcer or white or red patch on your mouth or tongue just won't go away - and has lingered for around three weeks - it's sensible to tell your dentist or doctor.
Ulcers or patches can sometimes be a symptom of mouth and oropharyngeal cancer, as can speech problems and finding it difficult to swallow.
Digestive problems are wide and far-reaching, and can include indigestion, persistent appetite loss, painful heartburn or bloating. Typically, your bloating could disappear as quickly as it appeared, but it can still warrant investigation.
And while heartburn is extremely common after eating a big, fatty or spicy meal, it is something to be concerned about if it's particularly painful. The NHS says digestive issues can be an early symptom of gastric cancer.
If you're feeling more breathless than usual, it's time to get checked out by a doctor. Likewise if you've been experiencing a persistent cough that you just can't shift.
Coughs and colds are, of course, very common, but if your cough doesn’t disappear within a few weeks or gets worse, it's sensible to seek medical care. Both the above can be signs of lung cancer.
Always be on the lookout for a wart, sore or spot that doesn't heal - even if it's not giving you any pain. You also need to be vigilant against any fresh moles or pre-existing moles that change in shape, size or colour, become itchy, crusty, hurt, bleed or ooze.
Your doctor should investigate any unusual changes in a nail a or patch of skin - whether it’s a change that's happened recently or not.
All of us should have some idea of what's normal for us when we go to the toilet. That way, if there are any changes we can then ask our doctor about them.
Changes to bowel habits can include looser poo, constipation or pooing more often. If these symptoms persist for more than three weeks then it's advisable to speak to your GP - as this could be a sign of bowel cancer.
As for urine, you could experience pain while peeing, have difficulty going or have a strong urgency. These could all be symptoms of bladder cancer. Though it is more likely a simple urinary tract infection.
Any blood in your poo or urine is a red flag for cancer, so it's important to speak to your doctor about them.