What is preventive chemotherapy? Kate Middleton's cancer ...

The treatment, known formally as adjuvant chemotherapy, is a course of anti-cancer drugs that is given to mop up any cancer cells that might remain in the body after primary cancer treatment, which is usually surgical removal of a tumour.

What does it do?

The therapy aims to reduce the risk of the original cancer coming back and spreading. This can happen when cancer cells, which are too small to detect with hospital scans and tests, are left behind after surgery. The risk of cancer returning tends to be smaller if the cancer is caught at a very early stage, before it has had a chance to spread, but greater if the disease is found at a later stage, or has spread to nearby lymph nodes.

How does the therapy work?

Most cancer chemotherapy drugs target rapidly dividing cells. A typical course of preventive chemotherapy lasts three to six months depending on the type and stage of the cancer, which is determined by examining the cancer removed during surgery. Occasionally, courses of adjuvant chemotherapy are given over several years.

How many courses of therapy do people have?

It depends on the nature of the original tumour that was picked up after surgery. When cancer is discovered during operations for other conditions, the tumour is often at an early stage, when subsequent chemotherapy is more effective. 

“This is likely to mean that a single course of chemotherapy will be sufficient to ensure that if any cancer cells are present, they will be destroyed,” says Prof Lawrence Young, the director of the Warwick Cancer Research Centre at the University of Warwick.

How effective is the therapy?

It is particularly effective for breast, bowel and lung cancer, but can be recommended for other forms of the disease, too. For example, adjuvant chemotherapy is often used after surgery for epithelial ovarian cancer, the most common form of ovarian cancer, because of the risk of the disease returning. Doctors decide whether adjuvant therapy is likely to have a benefit based on the type of cancer, how advanced the disease is, and other properties of the tumour.

Are there side effects?

No chemotherapy is completely harmless. The side effects depend on the specific drugs given, but patients can experience tiredness, nausea, vomiting, diarrhoea, an increased risk of picking up infections, and a loss of appetite. The side effects arise because the drugs affect not only cancer cells but all rapidly dividing cells, including hair, bone marrow, skin and the lining of the digestive system. The damage to healthy tissues tends to be temporary, however, and side effects usually disappear once the treatment is over.

Younger people often tolerate chemotherapy better than older patients and experience fewer side-effects because of their “greater functional reserves” and the “ability of young tissues to heal more rapidly,” says Dr Mangesh Thorat, an honorary reader at Queen Mary University of London and consultant breast surgeon at Homerton university hospital. Because of this, younger people may be given higher doses of the drugs, which are more likely to wipe out any cancer cells that remain in their bodies.

How long does it take to recover?

It depends on the patient and the particular drugs given, but it can take several months for a person to be back to full strength. Since younger people tend to be healthier and fitter than older people, their recovery times are usually shorter.