If our cancer survival rates were as high as the best in Europe, an estimated 11,000 lives would be saved each year, according to Cancer Research UK. "There is a general consensus that late diagnosis is the main cause for this discrepancy," says Sara Hiom, its director of health information. Poor public awareness of the symptoms of cancer, delays in seeing a doctor and late referral to hospital by GPs are all contributory factors.

There have been new initiatives over the past decade to encourage quicker hospital referrals, such as the issuing of clear guidelines to doctors about which symptoms warrant referrals, and a ruling that patients should never have to wait longer than two weeks to see a consultant after being referred (figures for the effects of these on survival rates are not yet available). For the public, however, there remains much confusion about what the symptoms of cancer really are and when to seek medical advice.

General symptoms of cancer

Most cancers, if caught early, are treatable and have good survival rates. A cancer is a disease caused by a malfunction of normal cells so that they grow in an uncontrolled way. As a cancer grows, it can cause symptoms related to where it is in the body, but as Dr Stephen Falk, consultant oncologist at the Bristol Oncology and Haematology Centre explains, there can often be other indicators. "Many general symptoms are not related to the lump itself but are related to the proteins that they secrete. Some very small cancers can cause severe systemic symptoms whereas some very large ones can cause none at all."

These symptoms include tiredness, loss of appetite, weight loss and night sweats. Although, of course, these usually indicate something far more benign. "At any one time 10% of people may report excessive tiredness," says Chris Martin, a GP in Essex. "Tiredness itself is not a very discriminating symptom. However, it may be a prompt to look for other symptoms and when there are other symptoms, it becomes much more significant."

Anyone who notices that a symptom is changing, getting worse or persists for longer than expected should seek medical advice. If you're going back to see a GP for a second time, try to see the same one as it can help them to compare how you are now with your previous visit. It is easy for GPs to forget to ask about their patients' worries, and it is not easy to tell a doctor that you're worried sick about something that might seem minor to them. However, it can be crucial that you discuss these concerns. Not only will it make you feel better, but it helps the diagnostic process: if something doesn't feel right it might need monitoring or more investigating.

Specific symptoms for the most common cancers

Breast

Breast cancer is the most common cancer in the UK, affecting more than 45,000 women and around 300 men each year. Four out of every five affected are women over the age of 50. Survival at five years from diagnosis (the standard measurement of cure rates in cancer trials) has risen from just over 50% to 80% in the past 30 years. When caught early, the survival rate is around 90%.

Usually, breast cancer doesn't make you feel any different and has no obvious symptoms. This is why screening and breast awareness are so important for early detection. "Women should be familiar with their own breasts" says Martin, "so that, should there be a significant change, they notice it and it would act as a prompt for further action."

Breast awareness campaigns stress the importance of telling a doctor about any changes as soon as possible. A delay of more than three months can adversely affect survival by more than 10%, according to a review of evidence in the Lancet. Changes you should tell your doctor about include: a new lump or thickening in one breast or armpit; changes in the size, shape or feel of the breasts; puckering, dimpling or redness of the skin; any changes to the nipple including a rash or discharge; new pain that is on only one side.

Lung

Although less common than breast cancer, lung cancer is the most likely form of the disease to cause death. More than 34,000 people died from it in 2006. Smokers are 15 times more likely to die from lung cancer than lifelong non-smokers. And more than two-thirds of cases are diagnosed at a late stage when they cannot be cured. Identifying lung cancer in the early stages is challenging, says Falk. "The symptoms of lung cancer are not different to other tobacco-related symptoms. However, a change in a cough may be significant."

Early symptoms commonly go unnoticed or are not associated with illness. Researchers in Southampton interviewed 22 people with recently diagnosed lung cancer. They experienced their first symptom an average of seven months before they realised they needed to seek medical advice. By the time they saw a doctor they each had an average of four symptoms. Anyone who coughs up blood, has an unexplained cough, breathlessness, or pains in the chest for three weeks or more or who is losing weight and doesn't know why should visit their GP.

"We have a rather nihilistic view of the outcomes of lung cancer" says Falk. "Patients have relatively low expectations." For survival rates to improve, these views have to change.

Bowel

Each year 36,000 people are diagnosed with bowel cancer. More than 80% are over 50. Five-year survival rates have doubled in the past 30 years but are still only 50% on average. However, patients diagnosed during its earliest stage have a much better outlook, with 83% surviving five years or more.

Bowel cancer can present its elf in a variety of ways depending on which part of the bowel is affected. Cancers close to the lower end often cause bleeding from the anus or a persistent change in the frequency or consistency of bowel motions. Although alarming, rectal bleeding alone is actually very unlikely to be due to bowel cancer.

A study by researchers at King's College London last year looked at 15,289 cases seen by GPs and found that only 2% were due to bowel cancer. Piles or small tears at the anus are very common and usually cause bleeding into the toilet bowl or on toilet paper. Dark blood mixed with the stool is more likely to be due to cancer.

A cancer that is further up the bowel may cause tiredness - due to blood loss into the gut causing anaemia. Other symptoms of bowel cancer include unintentional weight loss and the feeling of being unable to fully empty your bowels.

Prostate

The prostate is a small gland that sits below the bladder and in front of the rectum in men. Prostate cancer is the most common cancer in men in the UK. It is rarely diagnosed in those under 50, and becomes more common with increasing age. It usually grows more slowly than many other cancers and five-year survival rates are currently more than 70%.

Prostate cancer is often symptomless, and there are no simple and reliable tests to diagnose it, so it is difficult to estimate exactly how common it is. Postmortem studies have attempted to do this by looking for cancer cells in the prostates of men who died from other causes. They found that about half of men aged 50 and up to 80% of men aged 80 had evidence of cancer in the prostate. This suggests that many men have it but aren't affected by it.

Most symptoms are caused by the tumour pressing on the urethra (the tube that urine passes through after the bladder). These include difficulty in passing urine, increased frequency in passing urine and excessive dribbling afterwards. These symptoms are identical to those of a non-cancerous disease called benign prostatic hyperplasia (BPH). One way to tell the difference is to for a doctor to examine the prostate with their finger via the anus. In BPH the prostate is large and smooth, whereas in prostate cancer it is may be firm and irregular.

Non-Hodgkin's lymphoma

Lymphoma is a cancer of the lymphatic system. This includes the spleen, tonsils, thymus and lymph glands, and is important in fighting infection and moving fluid around the body. There are more than 10,000 new cases of
non-Hodgkin's lymphoma each year.

There are many different types of lymphoma and their naming can get quite confusing. Hodgkin's lymphoma is considered a separate disease to non-Hodgkin's lymphoma and, although the symptoms can be similar, is treated very differently. There are two main types of non-Hodgkin's lymphoma: low-grade and high-grade. "Low-grade tends to occur in the elderly," Martin explains. "It is common but people don't tend to die from it. High-grade affects younger age groups and is an aggressive disease."

Both cause rubbery swellings, often in the neck, and may cause general symptoms such as night sweats, weight loss and unexplained fevers. Non-cancerous swellings can occur around sites of infection, such as in the neck during a sore throat. However, any lump that appears in an unusual place or is getting bigger should be assessed by a doctor.

www.cancerresearchuk.org