Chemotherapy kills cells that are in the process of splitting into 2 new cells.

Body tissues are made of billions of individual cells. Once we are fully grown, most of the body’s cells don’t divide and multiply much. They only divide if they need to repair damage.

When cells divide, they split into 2 identical new cells. So where there was 1 cell, there are now 2. Then these divide to make 4, then 8 and so on.

In cancer, the cells keep on dividing until there is a mass of cells. This mass of cells becomes a lump, called a tumour.

Because cancer cells divide much more often than most normal cells, chemotherapy is much more likely to kill them.

Some drugs kill dividing cells by damaging the part of the cell’s control centre that makes it divide. Other drugs interrupt the chemical processes involved in cell division.

The effects on dividing cells

Chemotherapy damages cells as they divide.

In the centre of each living cell is a dark blob, called the nucleus. The nucleus is the control centre of the cell. It contains chromosomes, which are made up of genes.

These genes have to be copied exactly each time a cell divides into 2 to make new cells.

Chemotherapy damages the genes inside the nucleus of cells.

Some drugs damage cells at the point of splitting. Some damage the cells while they’re making copies of all their genes before they split. Chemotherapy is much less likely to damage cells that are at rest, such as most normal cells.

You might have a combination of different chemotherapy drugs. This will include drugs that damage cells at different stages in the process of cell division. This means there’s more chance of killing more cells.

Why chemotherapy causes side effects

The fact that chemotherapy drugs kill dividing cells helps to explain why chemotherapy causes side effects. It affects healthy body tissues where the cells are constantly growing and dividing, such as:

• your hair, which is always growing
• your bone marrow, which is constantly producing blood cells
• your skin and the lining of your digestive system, which are constantly renewing themselves

Because these tissues have dividing cells, chemotherapy can damage them. But normal cells can replace or repair the healthy cells that are damaged by chemotherapy.

So the damage to healthy cells doesn’t usually last. Most side effects disappear once your treatment is over. Some side effects such as sickness or diarrhoea might only happen during the days you are actually having the drugs.

How you have chemotherapy

You can have chemotherapy as:

• an injection into the bloodstream (through a vein)
• a drip (intravenous infusion) into the bloodstream through a vein
• tablets
• capsules

Chemotherapy drugs that you have in these ways circulate all around the body in the bloodstream. They can reach cancer cells almost anywhere in the body. This is known as systemic treatment.

How well chemotherapy works

The chance of the chemotherapy curing your cancer depends on the type of cancer you have.

• With some types of cancer, most people are cured by chemotherapy
• With other types of cancer, fewer people are completely cured

Examples of cancers where chemotherapy works very well are testicular cancer and Hodgkin lymphoma.

With some cancers, chemotherapy can’t cure the cancer on its own. But it can help in combination with other types of treatment.

For example, many people with breast or bowel cancer have chemotherapy after surgery to help lower the risk of the cancer coming back.

With some cancers, if a cure is unlikely, your doctor may still suggest chemotherapy to:

• shrink the cancer
• relieve your symptoms
• give you a longer life by controlling the cancer or putting it into remission

Can chemotherapy be given as tablets?

Oral chemotherapy is a cancer-fighting drug given by mouth in tablet, capsule, or liquid form. It is prescribed by your doctor, nurse practitioner, or physician’s assistant, and has the same benefits and risks as chemotherapy given by infusion. Today, many cancer patients receive oral chemotherapy as a treatment.

Is chemotherapy expensive?

The price of chemotherapy varies depending on the kind of drugs used as part of the protocol. The price of all chemotherapy drugs has been falling over time. Several treatment options are often available and in many cases, cheaper drugs may be as effective as more expensive drugs.

What are chemotherapy “cycles”? How long will I receive chemotherapy?

Conventionally, chemotherapy is given in “cycles”, where each dose of chemotherapy is separated from the next dose by one to four weeks. Chemotherapy is given in cycles to ensure that maximum possible tumor cells are killed while avoiding damage to normal body organs and preventing side-effects. The total duration of chemotherapy varies according to the type of disease it is being used for. You can look for more information on the page dealing with your specific cancer.

What kind of diet should I eat during chemotherapy?

There are no proven foods that improve or worsen the effects of chemotherapy. However, a few general principles apply:

Since the body’s immunity declines during chemotherapy, it is recommended that all food and water be hygienic and very clean. It is generally suggested not to eat any food whose cleanliness might be in doubt (for example: street food, food from restaurants with doubtful credentials, leftovers that have not been stored properly, delivered food, etc) and drink only properly treated water (Eg. Filtered, boiled or RO water). Do not eat raw or undercooked meat, fruit or vegetables. Fruits can be eaten, but only after removing the skin and thoroughly washing them.

If you wish to eat non-vegetarian food, it should be cooked ideally under your supervision. Meat/chicken/fish should be fresh and cut into small pieces (which can be cooked all the way through) and cooked carefully at high temperature so that there is no risk of infection. If you cannot ensure these precautions, you may wish to avoid non-vegetarian food.

High protein diets boost your strength during chemotherapy. High protein foods include dal, soyabean, paneer/cheese, non-vegetarian food. Protein supplements may be prescribed by your oncologist in some cases.

Ensure you get adequate amount of calories. If your diet is poor due to nausea, vomiting or change in taste, try changing to preferred food, add flavour by condiments or spices. Eat multiple small meals instead of three large meals.

If you are a diabetic, monitor your blood sugars closely as they may fluctuate on chemotherapy.