Lung cancer is one of the most common and serious types of cancer. Over 41,000 people are diagnosed with the condition every year in the UK.
There are usually no signs or symptoms in the early stages of lung cancer, but many people with the condition will eventually develop symptoms including:
a persistent cough
coughing up blood
unexplained tiredness and weight loss
an ache or pain when breathing or coughing
You should see your GP if you have these symptoms.
Types of lung cancer
Cancer that begins in the lungs is called primary lung cancer. Cancer that begins in another part of the body and spreads to the lungs is known as secondary lung cancer. This page is about primary lung cancer.
There are two main types of primary lung cancer. These are classified by the type of cells in which the cancer starts. They are:
non-small-cell lung cancer – the most common type, accounting for more than 80% of cases; can be either squamous cell carcinoma, adenocarcinoma or large-cell carcinoma
small-cell lung cancer – a less common type that usually spreads faster than non-small-cell lung cancer
The type of lung cancer you have will determine which treatments are recommended.
Who is affected
Lung cancer mainly affects older people. It is rare in people younger than 40, but the rates of lung cancer rise sharply with age. Lung cancer is most commonly diagnosed in people aged 70-74 years.
Although people who have never smoked can develop lung cancer, smoking is the main cause (about 90% of cases). This is because smoking involves regularly inhaling a number of different toxic substances.
Treating lung cancer
The treatment for lung cancer depends on the type of cancer, how far it has spread and how good your general health is.
If the condition is diagnosed early and the cancerous cells are confined to a small area, surgery to remove the affected area of lung is usually recommended.
If surgery is unsuitable due to your general health, radiotherapy to destroy the cancerous cells may be recommended instead.
If the cancer has spread too far for surgery or radiotherapy to be effective, chemotherapy is usually used.
As lung cancer does not usually cause noticeable symptoms until it has spread through much of the lungs or into other parts of the body, the outlook for the condition is not as good as many other types of cancer.
Overall, about 1 in 3 people with the condition will live for at least a year after they are diagnosed and fewer than 1 in 10 people will live at least five years.
However, survival rates can vary widely depending on how far the cancer has spread at the time of the diagnosis. Early diagnosis can make a big difference.
Symptoms of lung cancer
There are usually no signs or symptoms in the early stages of lung cancer. However, symptoms develop as the condition progresses.
The main symptoms of lung cancer are listed below. If you have any of these, you should see your GP:
a cough that doesn’t go away after two or three weeks
a long-standing cough that gets worse
persistent chest infections
coughing up blood
an ache or pain when breathing or coughing
persistent tiredness or lack of energy
loss of appetite or unexplained weight loss
Less common symptoms of lung cancer include:
changes in the appearance of your fingers, such as becoming more curved or their ends becoming larger (this is known as finger clubbing)
a high temperature (fever) of 38°C (100.4°F) or above
difficulty swallowing or pain when swallowing
a hoarse voice
swelling of your face or neck
persistent chest or shoulder pain
Want to know more?
Cancer Research UK: symptoms of lung cancer
Macmillan: symptoms of lung cancer
Causes of lung cancer
Most cases of lung cancer are caused by smoking, although people who have never smoked can also develop the condition.
Smoking cigarettes is the single biggest risk factor for lung cancer. It is responsible for about 90% of all cases.
Tobacco smoke contains more than 60 different toxic substances, which can lead to the development of cancer. These substances are known to be carcinogenic (cancer-producing).
If you smoke more than 25 cigarettes a day, you are 25 times more likely to get lung cancer than a non-smoker.
While smoking cigarettes is the biggest risk factor, using other types of tobacco products can also increase your risk of developing lung cancer and other types of cancer, such as oesophageal cancer and mouth cancer. These products include:
snuff (a powdered form of tobacco)
Smoking cannabis has also been linked to an increased risk of lung cancer. Most cannabis smokers mix their cannabis with tobacco. While they tend to smoke less than tobacco smokers, they usually inhale more deeply and hold the smoke in their lungs for longer.
It has been estimated that smoking four joints (homemade cigarettes mixed with cannabis) may be as damaging to the lungs as smoking 20 cigarettes.
Even smoking cannabis without mixing it with tobacco is potentially dangerous. This is because cannabis also contains substances that can cause cancer.
If you do not smoke, frequent exposure to other people’s tobacco smoke (passive smoking) can increase your risk of developing lung cancer.
For example, research has found that non-smoking women who share their house with a smoking partner are 25% more likely to develop lung cancer than non-smoking women who live with a non-smoking partner.
Radon is a naturally occurring radioactive gas that comes from tiny amounts of uranium present in all rocks and soils. It can sometimes build up in buildings.
If radon is breathed in, it can damage your lungs, particularly if you are a smoker. Radon is estimated to be responsible for about 3% of all lung cancer deaths in England.
Occupational exposure and pollution
Exposure to certain chemicals and substances that are used in several occupations and industries has been linked to a slightly higher risk of developing lung cancer. These chemicals and substances include arsenic, asbestos, beryllium, cadmium, coal and coke fumes, silica and nickel.
Research also suggests that being exposed to large amounts of diesel fumes for many years may increase your risk of developing lung cancer by up to 50%. One study has shown that your risk of developing lung cancer increases by about a third if you live in an area with high levels of nitrogen oxide gases (mostly produced by cars and other vehicles).
Want to know more?
Cancer Research UK: smoking and lung cancer
Macmillan: causes and risk factors for lung cancer
Diagnosing lung cancer
You should see your GP if you have symptoms of lung cancer, such as breathlessness or a persistent cough.
Your GP will ask you about your general health and what symptoms you have been experiencing. They may examine you and ask you to breathe into a device called a spirometer, which measures how much air you breathe in and out.
You may be asked to have a blood test to rule out some of the possible causes of your symptoms, such as a chest infection.
If you have been coughing up blood or you have other persistent signs of lung cancer, you should be referred for a chest X-ray or directly to a specialist in chest conditions within two weeks.
A chest X-ray is usually the first test that is used to diagnose lung cancer. Most lung tumours show up on X-rays as a white-grey mass.
However, chest X-rays cannot give a definitive diagnosis because they often cannot distinguish between cancer and other conditions, such as a lung abscess (a collection of pus that forms in the lungs).
If your chest X-ray suggests you may have lung cancer, you should be referred to a specialist (if you've haven't already been) in chest conditions such as lung cancer. A specialist can carry out more tests to investigate whether you have lung cancer and, if you do, what type it is and how much it has spread.
A computerised tomography (CT) scan is usually carried out after a chest X-ray. A CT scan uses X-rays and a computer to create detailed images of the inside of your body.
Before having a CT scan, you will be given an injection of a contrast medium. This is a liquid containing a dye that makes the lungs show up more clearly on the scan. The scan is painless and takes 10-30 minutes to complete.
A PET-CT scan (which stands for positron emission tomography-computerised tomography) may be carried out if the results of the CT scan show that you have cancer at an early stage.
The PET-CT scan can show where there are active cancer cells. This can help with diagnosis and treatment.
Before having a PET-CT scan, you will be injected with a slightly radioactive material. You will be asked to lie down on a table, which will slide into the PET scanner. The scan is painless and takes around 30-60 minutes to complete.
Bronchoscopy and biopsy
If the CT scan shows that there might be cancer in the central part of your chest, you will have a bronchoscopy. A bronchoscopy is a procedure that allows a doctor or nurse to remove a small sample of cells from inside your lungs.
During a bronchoscopy, a thin tube called a bronchoscope is used to examine your lungs and take a sample of cells (biopsy). The bronchoscope is passed through your mouth or nose, down your throat and into the airways of your lungs.
The procedure may be uncomfortable, but you will be given a mild sedative beforehand to help you relax and a local anaesthetic to make your throat numb. The procedure is very quick and only takes a few minutes.
Other types of biopsy
If you're not able to have one the biopsies described above or you've had one and the results weren't clear, you may be offered a different type of biopsy. This may be a type of surgical biopsy such as a thoracoscopy or a mediastinoscopy, or a biopsy carried out using a needle inserted through your skin.
These types of biopsy are described below.
Percutaneous needle biopsy
A percutaneous needle biopsy involves removing a sample from a suspected tumour to test it at a laboratory for cancerous cells.
The doctor carrying out the biopsy will use a CT scanner to guide a needle to the site of a suspected tumour through the skin. A local anaesthetic is used to numb the surrounding skin, and the needle is passed through your skin and into your lungs. The needle will then be used to remove a sample of tissue for testing.
A thoracoscopy is a procedure that allows the doctor to examine a particular area of your chest and take tissue and fluid samples.
You are likely to need a general anaesthetic before having a thoracoscopy. Two or three small cuts will be made in your chest to pass a tube (similar to a bronchoscope) into your chest. The doctor will use the tube to look inside your chest and take samples. The samples will then be sent away for tests.
After a thoracoscopy, you may need to stay in hospital overnight while any further fluid in your lungs is drained out.
A mediastinoscopy allows the doctor to examine the area between your lungs at the centre of your chest (mediastinum).
For this test, you will need to have a general anaesthetic and stay in hospital for a couple of days. The doctor will make a small cut at the bottom of your neck so that they can pass a thin tube into your chest.
The tube has a camera at the end, which enables the doctor to see inside your chest. They will also be able to take samples of your cells and lymph nodes at the same time. The lymph nodes are tested because they are usually the first place that lung cancer spreads to.
Once the above tests have been completed, it should be possible to work out what stage your cancer is, what this means for your treatment and whether it's possible to completely cure the cancer.
Non-small-cell lung cancer
Non-small-cell lung cancer (the most common type) usually spreads more slowly than small-cell lung cancer and responds differently to treatment.
The stages of non-small-cell lung cancer are outlined below.
The cancer is contained within the lung and has not spread to nearby lymph nodes. Stage 1 can also be divided into two sub-stages:
stage 1A – the tumour is less than 3cm in size (1.2 inches)
stage 1B – the tumour is 3-5cm (1.2–2 inches)
Stage 2 is divided into two sub-stages: 2A and 2B.
In stage 2A lung cancer:
the tumour is 5-7cm
the tumour is less than 5cm and cancerous cells have spread to nearby lymph nodes
In stage 2B lung cancer:
the tumour is larger than 7cm
the tumour is 5-7cm and cancerous cells have spread to nearby lymph nodes
the cancer has not spread to lymph nodes but has spread to surrounding muscles or tissue
the cancer has spread to one of the main airways (bronchus)
the cancer has caused the lung to collapse
there are multiple small tumours in the lung
Stage 3 is divided into two sub-stages: 3A and 3B.
In stage 3A lung cancer, the cancer has either spread to the lymph nodes in the middle of the chest or into the surrounding tissue. This can be:
the covering of the lung (the pleura)
the chest wall
the middle of the chest
other lymph nodes near the affected lung
In stage 3B lung cancer, the cancer has spread to either of the following:
lymph nodes on either side of the chest, above the collarbones
another important part of the body, such as the gullet (oesophagus), windpipe (trachea), heart or into a main blood vessel
In stage 4 lung cancer, the cancer has either spread to both lungs or to another part of the body (such as the bones, liver or brain), or the cancer has caused fluid-containing cancer cells to build up around your heart or lungs.
Small-cell lung cancer
Small-cell lung cancer is less common than non-small-cell lung cancer. The cancerous cells responsible for the condition are smaller in size when examined under a microscope than the cells that cause non-small-cell lung cancer.
Small-cell lung cancer only has two possible stages:
limited disease – the cancer has not spread beyond the lung
extensive disease – the cancer has spread beyond the lung
Want to know more?
Macmillan: how lung cancer is diagnosed
Cancer Research UK: types of lung cancer
Lung cancer screening
There is currently no national screening programme for lung cancer in the UK.
This is because current tests for lung cancer are not simple, quick or sensitive enough to outweigh the risks associated with screening (such as radiation exposure during X-rays).
Treating lung cancer
You will be cared for by a team of specialists who will work together to provide the best possible treatment.
This team will contain all the specialists required to make a proper diagnosis, to stage your cancer and to plan the best treatment. If you want to know more, ask your specialist about this.
The type of treatment you will receive for lung cancer depends on several factors, including:
the type of lung cancer you have (non-small-cell or small-cell cancer)
the size and position of the cancer
how far advanced your cancer is (the stage)
your overall health
Deciding what treatment is best for you can be difficult. Your cancer team will make recommendations, but the final decision will be yours.
The main treatment options include surgery, radiotherapy and chemotherapy. Depending on your type of cancer and how advanced it is, you may receive a combination of these treatments.
Your treatment plan
Your treatment plan will depend on whether you have non-small-cell lung cancer or small-cell lung cancer.
Non-small-cell lung cancer
If you have non-small-cell lung cancer that is confined to one lung and you are in good general health, you'll probably have surgery to remove the cancerous cells. This may be followed by a course of chemotherapy to destroy any cancer cells that may have remained in the body.
If the cancer has not spread too far but surgery is not possible (for example, if your general health means you have an increased risk of developing complications), radiotherapy to destroy the cancerous cells will usually be recommended. In some cases, this may be combined with chemotherapy (known as chemoradiotherapy).
If the cancer has spread too far for surgery or radiotherapy to be effective, chemotherapy is usually recommended. If the cancer starts to grow again after initial chemotherapy treatment, another course of treatment may be recommended.
In some cases, a treatment called biological or targeted therapy may be recommended as an alternative to chemotherapy, or after chemotherapy. Biological therapies are medications that can control or stop the growth of cancer cells.
Small-cell lung cancer
Small-cell lung cancer is usually treated with chemotherapy, either on its own or in combination with radiotherapy. This can help prolong life and relieve symptoms.
Surgery isn't usually used to treat this type of lung cancer. This is because often the cancer has already spread to other areas of the body by the time it's diagnosed. However, if the cancer is found very early, surgery may be used. In these cases, chemotherapy or radiotherapy may be given after surgery to help reduce the risk of the cancer returning.
There are three types of lung cancer surgery:
Lobectomy – where one or more large parts of the lung (called lobes) are removed. Your doctors will suggest this operation if the cancer is just in one section of one lung.
Pneumonectomy – where the entire lung is removed. This is used when the cancer is located in the middle of the lung or has spread throughout the lung.
Wedge resection or segmentectomy – where a small piece of the lung is removed. This procedure is only suitable for a small number of patients as it is only used if your doctors think your cancer is small and limited to one area of the lung. This is usually very early-stage non-small-cell lung cancer.
People are naturally concerned that they will not be able to breathe if some or all of a lung is removed, but it is possible to breathe normally with one lung. However, if you have breathing problems before the operation, such as breathlessness, it is likely that these symptoms will continue after surgery.
Tests before surgery
Before surgery can take place, you will need to have a number of tests to check your general state of health and your lung function. These may include:
an electrocardiograph (ECG) – electrodes are used to monitor the electrical activity of your heart
spirometry – you will breathe into a machine called a spirometer, which measures how much air your lungs can breathe in and out
How it's performed
Surgery is usually performed by making a cut (incision) in your chest or side, and removing a section or all of the affected lung. Nearby lymph nodes may also be removed if it is thought that the cancer may have spread to them.
In some cases, an alternative to this approach, called video-assisted thoracoscopic surgery (VATS), may be suitable. VATS is a type of keyhole surgery, where small incisions are made in the chest. A small fibre-optic camera is inserted into one of the incisions, so the surgeon can see images of the inside of your chest on a monitor.
After the operation
You will probably be able to go home five to 10 days after your operation. However, it can take many weeks to recover fully from a lung operation.
After your operation, you will be encouraged to start moving about as soon as possible. Even if you have to stay in bed, you will need to keep doing regular leg movements to help your circulation and prevent blood clots from forming. A physiotherapist will show you breathing exercises to help prevent complications.
When you go home, you will need to exercise gently to build up your strength and fitness. Walking and swimming are good forms of exercise that are suitable for most people after treatment for lung cancer. Talk to your care team about which types of exercise are suitable for you.
As with all surgery, lung surgery carries a risk of complications. These are estimated to occur in one out of every five cases. These complications can usually be treated using medication or additional surgery, which may mean you need to stay longer in hospital.
Complications of lung surgery can include:
inflammation or infection of the lung (pneumonia)
a blood clot in the leg (deep vein thrombosis), which could potentially travel up to the lung (pulmonary embolism)
Radiotherapy is a type of treatment that uses pulses of radiation to destroy cancer cells. There are a number of ways it can be used to treat people with lung cancer.
An intensive course of radiotherapy, known as radical radiotherapy, can be used to try to cure non-small-cell lung cancer if the person is not healthy enough for surgery. For very small tumours, a special type of radiotherapy called stereotactic radiotherapy may be used instead of surgery.
Radiotherapy can also be used to control the symptoms and slow the spread of cancer when a cure is not possible (this is known as palliative radiotherapy).
A type of radiotherapy known as prophylactic cranial irradiation (PCI) is also sometimes used during the treatment of small-cell lung cancer. PCI involves treating the whole brain with a low dose of radiation. It is used as a preventative measure because there is a risk that small-cell lung cancer will spread to your brain.
The three main ways that radiotherapy can be given are described below:
Conventional external beam radiotherapy – a machine is used to direct beams of radiation at affected parts of your body.
Stereotactic radiotherapy – a more accurate type of external beam radiotherapy where several high-energy beams are used to deliver a higher dose of radiation to the tumour, while sparing the surrounding healthy tissue as much as possible.
Internal radiotherapy – a catheter (thin tube) is inserted into your lung. A small piece of radioactive material is placed inside the catheter and positioned against the site of the tumour before being removed after a few minutes.
For lung cancer, external beam radiotherapy is used more often than internal radiotherapy, particularly if it is thought that a cure is possible. Stereotactic radiotherapy may be used to treat tumours that are very small, as it is more effective than standard radiotherapy alone in these circumstances.
Internal radiotherapy only tends to be used as a palliative treatment where the cancer is blocking or partly blocking your airway.
Courses of treatment
A course of radiotherapy treatment can be planned in several different ways.
Radical radiotherapy is usually given five days a week, with a break at weekends. Each session of radiotherapy lasts 10-15 minutes and the course usually lasts between four and seven weeks.
Continuous hyperfractionated accelerated radiotherapy (CHART) is an alternative method of delivering radical radiotherapy. CHART is given three times a day for 12 days in a row.
For stereotactic radiotherapy, fewer treatment sessions are needed because a higher dose of radiation is delivered with each treatment. People having conventional radical radiotherapy are likely to have around 20-32 treatment sessions, whereas stereotactic radiotherapy typically only requires between three and 10 sessions.
Palliative radiotherapy usually only requires one to five sessions to control your symptoms.
Side effects of radiotherapy to the chest include:
persistent cough that may bring up blood-stained phlegm (this is normal and nothing to worry about)
difficulties swallowing (dysphagia)
redness and soreness of the skin, which looks and feels like sunburn
hair loss on your chest
Side effects should pass once the course of radiotherapy has been completed.
Chemotherapy uses powerful cancer-killing medication to treat cancer. There are several different ways that chemotherapy can be used to treat lung cancer. For example, it can be:
given before surgery to shrink a tumour, which can increase the chance of successful surgery (this is usually only done as part of a clinical trial)
given after surgery to prevent the cancer returning
used to relieve symptoms and slow the spread of cancer when a cure is not possible
combined with radiotherapy
Chemotherapy treatments are usually given in cycles. A cycle involves taking the chemotherapy medication for several days, then having a break for a few weeks to let your body recover from the effects of the treatment.
The number of cycles of chemotherapy that you need will depend on the type and the grade of your lung cancer. Most people require between four and six courses of treatment over three to six months.
Chemotherapy for lung cancer involves taking a combination of different medications. The medications are usually delivered through a drip into your vein, or into a tube that is connected to one of the blood vessels in your chest.
Side effects of chemotherapy can include:
These side effects should gradually pass once your treatment has finished, or you may be able to take other medicines to make you feel better during your chemotherapy.
Chemotherapy can also weaken your immune system, making you more vulnerable to infection. Tell your care team or GP as soon as possible if you have the possible signs of an infection, such as a high temperature (fever) of 38C (100.4F) or higher, or suddenly feeling generally unwell.
As well as surgery, radiotherapy and chemotherapy, there are a number of other treatments that are sometimes used to treat lung cancer. These are described below.
Biological therapies are new medications that are sometimes recommended as an alternative treatment to chemotherapy for non-small-cell cancer that has spread too far for surgery or radiotherapy to be effective.
Examples of biological therapies include erlotinib and gefitinib. These are also called growth factor inhibitors because they work by disrupting the growth of the cancer cells.
Biological therapies are only suitable for people who have certain proteins in their cancerous cells. Your doctor may be able to request tests on a small sample of cells removed from your lung (biopsy) to determine whether these treatments are likely to be suitable for you.
Radiofrequency ablation is a new type of treatment that can treat non-small-cell lung cancer diagnosed at an early stage.
The doctor carrying out the treatment will use a computerised tomography (CT) scanner to guide a needle to the site of the tumour. The needle will be pressed into the tumour and radio waves will be sent through the needle. These waves generate heat, which kills the cancer cells.
The most common complication of radiofrequency ablation is that a pocket of air gets trapped between the inner and outer layer of your lungs (pneumothorax). This can be treated by placing a tube into the lungs to drain away the trapped air.
Cryotherapy is a treatment that can be used if the cancer starts to block your airways. This is known as endobronchial obstruction, and it can cause symptoms such as:
coughing up blood
Cryotherapy is performed in a similar way to internal radiotherapy, except that instead of using a radioactive source, a device known as a cryoprobe is placed against the tumour. The cryoprobe can generate very cold temperatures, which help shrink the tumour.
Photodynamic therapy (PDT) is a treatment that can be used to treat early-stage lung cancer when a person is unable or unwilling to have surgery. It can also be used to remove a tumour that is blocking the airways.
Photodynamic therapy is carried out in two stages. Firstly, you will be given an injection of a medication that will make the cells in your body very sensitive to light.
The next stage is carried out 24-72 hours later. A thin tube will be guided to the site of the tumour, and a laser will be beamed through it. The cancerous cells, which are now more sensitive to light, will be destroyed by the laser beam.
Side effects of photodynamic therapy can include inflammation of the airways and a build-up of fluid in the lungs. Both these side effects can cause symptoms of breathlessness and lung and throat pain. However, these symptoms should gradually pass as your lungs recover from the effects of the treatment.
Your doctor can prescribe a medicine outside its licensed use if they are willing to take personal responsibility for this "off-licence" use of the medication.
Living with lung cancer
Lung cancer can affect your daily life in different ways, depending on what stage it is at and what treatment you are having.
Although not all these steps work for everybody, there are several ways that you can find support to help you cope:
talk to your friends and family
talk to other people in the same situation
know about your condition
don't try to do too much
make time for yourself
Lung cancer specialist nurses
Your specialist team should have at least one lung cancer nurse specialist (CNS) working with them. Ask your specialist to make sure you see a specialist nurse. They can support you and provide information about other sources of support and advice.
Want to know more?
The Roy Castle Lung Cancer Foundation: living with lung cancer
Cancer Research UK: living with lung cancer
Macmillan: adjusting to life after cancer
Breathlessness is common in people who have lung cancer, whether it is a symptom of the condition or a side effect of treatment.
In many cases, breathlessness can be improved with some simple measures such as:
breathing in slowly through your nose and out through your mouth (after treatment for lung cancer, you may see a physiotherapist who can teach you some simple breathing exercises)
making daily activities easier – for example, using a trolley when you go shopping or keeping things you often need downstairs so you don't need to regularly walk up and down the stairs
using a fan to direct cool air towards your face
eating smaller and more frequent meals, and taking smaller mouthfuls
If measures like these are not enough to control your breathlessness, you may need further treatment. There are a number of medications that can help improve breathlessness and home oxygen treatment may be an option in more severe cases.
If your breathlessness is caused by another condition, such as a chest infection or a fluid build-up around the lungs (a pleural effusion), treating this underlying cause may help your breathing.
Want to know more?
Macmillan: managing breathlessness
Cancer Research UK: coping with breathlessness
The Roy Castle Lung Cancer Foundation: coping with breathlessness
Macmillan: pleural effusion
Preventing lung cancer
Not smoking is the most effective way to avoid getting lung cancer.
If you smoke, the best way to prevent lung cancer and other serious conditions is to stop smoking as soon as possible.
However long you have been smoking, it is always worth quitting. Every year that you do not smoke, your risk of getting serious illnesses, such as lung cancer, will decrease. After 10 years of not smoking, your chances of developing lung cancer falls to half that of some who smokes.
Your GP or pharmacist can also give you help and advice about giving up smoking.
Research suggests that eating a low-fat, high-fibre diet, including at least five portions a day of fresh fruit and vegetables and plenty of whole grains, can help reduce your risk of lung cancer, as well as other types of cancer and heart disease.
There is strong evidence to suggest that regular exercise can lower the risk of developing lung cancer and other types of cancer.
Adults should do at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity each week.