This information is for people who have non-small-cell lung cancer that hasn't spread beyond their chest (stage 3 lung cancer) but which can't be operated on.

If you have both chemotherapy and radiation therapy, you're likely to live longer than if you have only radiation therapy. But if you're over 70, this combination of treatments may be harmful. The treatment may be too much for your body to handle. Also, researchers don't know how this combination of treatments affects your symptoms and the way you feel.

Radiation therapy uses high-energy X-rays to kill lung cancer cells and to shrink tumors. For people with lung cancer, the radiation therapy is given to their chest area. A large machine usually produces these rays. You will be asked to lie inside the radiation therapy machine and to keep very still while you have the treatment. It only takes a few minutes, and it does not hurt. You may feel rather isolated, and it's natural to feel anxious about the treatment. But your medical team will be able to reassure you while they are getting ready.

Your doctors will have worked out exactly where your cancer is and how much energy they need to direct at it, and for how long. They want to destroy your cancer but cause as little damage as possible to the normal, healthy cells around it. So they target the X-ray beam very carefully. They do this by sending the X-rays toward your cancer from different directions. It's like sending an army of tanks on an exercise, using different routes to get to the same place. If they all went the same way, they'd tear up the road. But, by going different routes, they cause smaller amounts of damage that are easier to repair.

There are several other methods doctors use to give radiation therapy to people with lung cancer. For more details, see Other ways doctors give radiation therapy.

Chemotherapy uses anti-cancer drugs to kill cancer cells in the lung and all over the body. Most anti-cancer drugs are injected directly into a vein, though some are taken as pills or injected into a muscle or under the skin. They can be given alone or as combinations of two, three or more drugs.

Examples of chemotherapy drugs (and their brand names) are:

• cisplatin (Platinol)
• cyclophosphamide (Cytoxan, Neosar)
• doxorubicin (Adriamycin, Rubex)
• etoposide (VePesid, Etopophos, Toposar).

Chemotherapy is usually given as a course of several cycles of treatment. One cycle of chemotherapy is usually given over a few days. Afterward you will have a few weeks' rest to give your body a chance to recover from the harmful effects of the treatment. How many cycles you have will depend on your type of cancer and how well it responds to the chemotherapy. Some treatments are more intensive than others, and you may be given additional drugs to help prevent or relieve harmful effects, such as damage to your blood cells.

People with this type of lung cancer who have radiation as well as chemotherapy have a slightly higher chance of living longer than people who have only radiation therapy. Researchers found that there was a 2 percent to 3 percent higher chance of being alive two, three, four or five years after treatment. One recent study found that 10 in 100 people who had both treatments were alive three years after treatment.

Out of those who had just radiotherapy, only 2 in 100 were alive three years later.

But if you're over 70, combining chemotherapy and radiation therapy seems to shorten your life compared with just having radiation therapy. People over 70 who had both treatments lived for an average of about 11 months. People who just had radiation therapy lived for about 13 months.

There's not much information on the effects of these treatments on how people feel. So before you decide which treatment to have, you may want to ask your doctor about how you are likely to feel during and after treatment. You may find it helpful to talk to someone who has had the same treatment.

Radiation therapy and many forms of chemotherapy work by damaging the DNA in cancer cells. DNA is a chemical that is vital for the body's cells to survive, grow and divide. Damaging it with radiation therapy or chemotherapy means cells can't grow and replace each other. These treatments can shrink cancers and slow down their growth. Some anti-cancer drugs work by damaging other substances that cells need to keep multiplying.

Both radiation therapy and chemotherapy damage healthy cells in the body as well as cancer cells. But there should be less damage to healthy tissues than to the cancer.

We know a lot about the side effects of radiotherapy and chemotherapy but studies don't tell us much about the side effects you're likely to get when these two treatments are used together. However, one recent study found that people who had just radiotherapy had similar side effects to those who had both radiotherapy and chemotherapy.

Here's what we know about the side effects of each of these treatments.

The most serious problem after radiation therapy to the lung is swelling (inflammation) around your lungs. This can make it harder to breathe and give you chest pain. It usually gets better on its own, but if it doesn't it can be treated with steroids.

You may also feel very tired.

Your throat may swell. This can cause problems swallowing and eating, although these will go away after a while. And if the tube that leads from your throat to your stomach gets narrower, you may get indigestion and heartburn. To learn more see Side effects of radiation therapy.

All anti-cancer drugs have some harmful effects. This is because they not only affect cancer cells, but they also damage normal, healthy cells. Cells that multiply rapidly like cancer cells are affected most. These include cells found in:

• Skin and hair
• The bone marrow (the soft tissue inside your bones that makes red and white blood cells)
• The lining of the mouth and digestive system (this includes all the parts of your body involved in digesting your food such as your throat and stomach)
• The ovaries (the female sex organs where eggs are made) or the testicles (the male sex organs where sperm are produced).

Whether you get these harmful effects will depend on:

• The drug or drugs you are having
• The dose of each drug
• How well you are
• What steps you and your medical team take to prevent or relieve any harmful effects.

The problems you're most likely to get soon after chemotherapy are nausea and vomiting, infections, tiredness and diarrhea. In the years after chemotherapy, there's a chance that you could become infertile, get another type of cancer or have heart problems.