Cancer Treatment & Prevention

There are a variety of medical methods used to treat and prevent cancer. The specific treatment method used depends on many factors including the type of cancer, its location, whether it has spread (metastasised) throughout the body, and the patient’s general health. These treatments may be used separately, or together in conjunction with each other. If a cancer is found early, it is easier to use treatments such as surgery to cure it entirely, but if a cancer has progressed to a later stage, these methods might only be able to reduce or manage symptoms. Many of these treatments are harsh on the body and cause side effects.

Australia has a universal health care system (Medicare), meaning that everyone has access to medicine and health services. The cost of cancer treatment varies depending on the individual person and should be discussed before treatment between the health care provider and patient. The Australian government subsidises the cost of many prescription chemotherapy drugs which can be very expensive.

Information about the nature, risk and benefits of available treatments are given to the patients to help their decision making process. Informed consent is very important and must be obtained from the patient for the treatment to proceed. Patients have the right to refuse any or all cancer treatments. In these circumstances they will be given supportive therapy which aims to increase the quality of life for the patient and their family.

Surgery

Cancer-related surgery is undertaken with a variety of aims.

Types & Mechanisms

To diagnose cancer (biopsy)

In a biopsy, a small piece of tissue is removed from the target area. This can be used detect the presence of cancer by examining the types of cells in the sample taken. If cancer cells are found, the type of cancer may also be determined.

To cure cancer (curative surgery)

Surgery is one of the main cancer treatments, and in many cases can cure cancer entirely on its own. Surgery has the highest chance of cure when used to treat early stage cancers, as these are small and have not metastasised to other parts of the body. Whether surgery is an option depends on the type and stage of the cancer, and the patient’s general health.

The tumour and some surrounding normal tissue (a clear margin) is removed by the surgeon. Lymph nodes near the cancer may also be removed, as they might contain more cancer cells. The removed tissue is then examined in a laboratory, which gives doctors vital information regarding the cancer, including whether any further treatment will be needed.

The chance of successful curative surgery can be increased by having neo-adjuvant treatment beforehand, to shrink the tumour before the surgery.

To reconstruct a part of the body

Surgery can be used to recreate or reconstruct a part of the body that was removed as a result of cancer treatment. For example, a breast reconstruction can be done following a mastectomy (removal of a breast) in a patient with breast cancer.

To prevent or reduce the risk of cancer

Those who are at a high risk of a particular cancer type due to inherited genetic factors can undergo specific types of surgery to minimise the risk. For example, women at high risk of breast cancer may have their breasts removed, to greatly lower the chance that they will develop cancer later in life.

To control symptoms or extend life

People may have surgery to relieve symptoms if their cancers cannot be completely removed, or cured, with other treatments. For example, cancers in the abdomen can sometimes block the bowel and cause sickness and pain. An operation to remove or bypass the blockage can relieve these symptoms.

Surgery may also sometimes help to control pain by removing cancer that is pressing on a body organ or nerve.

Occasionally it is possible to remove cancer that has spread into nearby organs or to another part of the body. For example, people who have kidney cancer that has spread to the lung may be able to have surgery to remove the lung tumours. The surgery is unlikely to cure the cancer but can reduce symptoms and may help some people to live longer.

When is surgery used?

Surgery can be an effective cancer treatment, but its effectiveness depends a lot on the stage of the cancer – it is generally more effective on localised cancers that have not spread far. If cancer has spread or is at an advanced stage, surgery may not be the best treatment. Other treatments which can work throughout the whole body, such as chemotherapy or radiotherapy, may be better options.

In particular, surgery is not used for some types of blood cancers (leukaemias) and lymphatic cancers (lymphomas), because in these cases, the cancer cells are found throughout the body and cannot be easily removed with surgery.

If the tumour is located in a position where delicate surrounding tissue could be damaged, such as if it is near a blood vessel, surgery may not be possible.

Chemotherapy

What is chemotherapy?

In chemotherapy, anti-cancer drugs are used to destroy cancer cells. These drugs are cytotoxic: they are poisonous to cells, and therefore can slow down or kill cancer cells – however, they are not specific, so they also affect normal cells. There is a huge variety of chemotherapy drugs available: a patient’s treatment may involve one or more different drugs, and can be used in conjunction with other types of cancer treatment, such as surgery or radiation therapy.

Chemotherapy drugs have come a long way since they were accidentally discovered during World War II (Source: American Cancer Society). Nowadays extensive laboratory testing and clinical trials are conducted on any prospective drugs to ensure the safety and efficacy of the treatment. There are thousands of clinical trials carried out on all aspects of cancer including but not limited to prevention, detection and treatment. Some trials can take many many years to complete.

Chemotherapy can be given to the patient in several ways.

• Orally, via tablets and capsules.

• Injected through a needle in a vein, via a catheter (a special tube). This is usually in a large vein, such as in the neck or chest.

• Direct, localised delivery into an organ or tissue affected by cancer, instead of going through the bloodstream: this often has reduced side effects.

Aims of chemotherapy

The aims of chemotherapy treatment depend on the type of cancer being treated.

• Cure In some cases, a cancer will be completely cured by chemotherapy treatment, where all cancer cells are destroyed. Whether this is possible will depend on the cancer type – for example, chemotherapy is known to work very well for testicular cancer and Hodgkin lymphoma.

• To help other (primary) treatments If chemotherapy cannot cure a cancer entirely, it can be used together with other treatment types, commonly surgery. It is called neo-adjuvant if given before other treatments, and adjuvant if given after. Neo-adjuvant therapy aims to make the cancer smaller so the primary treatment is more effective. Adjuvant therapy aims to destroy any small cancer cells that might remain after the primary treatment – this also lowers the risk that the cancer will come back.

• To control the cancer If cure is not possible, chemotherapy can control the growth of the tumour – this can extend and improve the patient’s life by controlling the cancer or putting it into remission.

• Symptom relief When cancer cannot be cured, chemotherapy can also provide relief for symptoms such as pain. This is called palliative treatment.

Types of chemotherapy

Alongside the above aims, these are an alternate characterisation of the variations within chemotherapy.

• Adjuvant Destroy microscopic cells after surgery to prevent reoccurrence.

• Neoadjuvant Given prior to surgery to shrink cancer, allowing a less extensive surgical procedure.

• Induction Given to induce remission (lack of recurrence) – acute leukaemias.

• Consolidation Given once remission is achieved in order to maintain the remission. Often called intensification therapy.

• Maintenance Given in lower doses to help prolong remission. Only used for certain types of cancers, such as acute leukaemias.

• First line (standard therapy) Conventional treatment determined to have the best probability of treating a given cancer. Based on research studies and clinical trials.

• Second line (salvage therapy) Given if disease has not responded to first line chemotherapy or if there is a recurrence after first line.

• Palliative Given to manage a patient’s symptoms without expecting to reduce the cancer significantly. Often used in terminal patients (e.g. stage IV lung cancers).

Mechanisms of action

Chemotherapy kills cells that are in the process of cell division, when they split into 2 new cells. In cancer, cells divide uncontrollably to form a tumour – because cancer cells divide much more frequently than normal cells, chemotherapy can effectively target and kill them.

Chemotherapy damages the genes inside cell nuclei that control cell division. Different drugs target dividing cells at different points of the cell cycle: some target the point of division (mitosis), while some damage cells that are replicating their DNA. Cells that are at rest (not actively dividing), are much less likely to be damaged by chemotherapy. However, they can still be targeted by cell-cycle non-specific drugs. Often, a combination of drugs will be used, so that different points of the cell cycle will all be targeted: this enables more cancer cells to be killed.

When the cancer cells lose their ability to divide, they die. The faster that cancer cells divide, the more likely it is that chemotherapy will kill the cells, causing the tumor to shrink. The drugs may also induce cell death (apoptosis).

The length of chemotherapy treatment depends on the cancer’s type and severity, as well as the types of drugs that have been used. Chemotherapy is generally given in cycles, which has two main benefits: cancer cells can be attacked at their most vulnerable, and normal cells are given some time to recover between cycles. When scheduling treatment, it is important to consider the type of cells involved, their rate of division, and the likely effectiveness of the given drug.

• When cure is the treatment goal, adjuvant chemotherapy may last 4-6 months, and is common in breast and colon cancer. In other cancers, the treatment may last up to a year.

• If the disease disappears completely, chemotherapy may continue for another 1-2 cycles to try and ensure that all microscopic disease was attacked.

• If the disease shrinks but does not disappear, chemotherapy will continue as long as it is tolerated and the disease does not grow.

• If the disease grows, chemotherapy will be stopped. Different drugs may be given, or depending on the patient’s health, the chemotherapy may be stopped and focus will be changed to maintaining the patient’s comfort.

Side effects of chemotherapy

In some, but not all, cases, chemotherapy will cause side effects. These are often temporary and can be managed.

Because chemotherapy drugs kill any dividing cells, they do not know the difference between cancer cells and normal cells – so normal cells are often affected or killed. The “normal” cells will eventually grow back and be healthy, but in the meantime, side effects will occur.

Normal cells most commonly affected by chemotherapy are the ones that are constantly dividing or renewing themselves. These include blood cells, the cells in the mouth, stomach and bowel, skin, bone marrow, and the hair follicles. For example, your hair is always growing due to constant cell division, so chemotherapy can often cause hair loss. Different drugs may affect different parts of the body. Possible side-effects include:

• nausea and vomiting
• diarrhoea or constipation (often due to anti-nausea medication)
• fatigue (tiredness)
• mouth sores or ulcers
• increased risk of infection
• increased risk of bruising
• hair loss
• muscle weakness
• skin sensitivity to sunlight (specific drugs only)
• dry or tired eyes
• loss of appetite

Having any of the above side-effects is not related to whether the chemotherapy is working or not. 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 treatment is over, and some only happen during the days while you are actually having the drugs, for example, sickness or diarrhoea.

Radiotherapy

What is radiotherapy?

In radiotherapy, radiation (usually in the form of X-rays) is used to damage the DNA within cancer cells, thus destroying them. They may do this by directly damaging the DNA, or by creating very reactive particles called free radicals, which can attack DNA. This DNA damage will then cause the cancer cell to stop growing or die – the body can then break down the dead cells and dispose of them as waste. Normal cells in the targeted area may also be damaged or affected, but they are generally able to repair themselves. Radiotherapy is a major and common form of cancer treatment, and approximately one in two patients recently diagnosed with cancer would potentially benefit from radiotherapy treatment.

Aims of radiotherapy

Similar to other forms of treatment, radiotherapy may be given with different treatment goals depending on the patient’s health and the stage of the cancer.

• Cure Curative treatment aims to cure the cancer entirely, either on its own or combined with other treatment types.

• Control Radiotherapy used to control the cancer’s growth, by shrinking the tumour or stopping its spread.

• Help other treatments Radiotherapy is used before (neoadjuvant) or after (adjuvant) other treatments, such as surgery or chemotherapy. This aims to increase the effectiveness of the main treatment.

• Symptom relief (palliative treatment) Radiotherapy can be used to manage or relieve symptoms such as pain, to improve the patient’s wellbeing.

Types of radiotherapy

External radiotherapy

External radiotherapy uses radiation from a machine, commonly a Linear Accelerator Machine (LINAC). High energy X-ray beams, or other types of particle beams (such as protons or electrons), are directed at the affected area and destroy cancer cells there. The radiotherapy treatment field must cover the entire area of the cancer, as well as a margin of surrounding normal tissue, to ensure a high chance of treating the cancer well.

Internal radiotherapy

Internal radiotherapy is only used for certain types of cancer, for example prostate, gynaecological, thyroid, and liver cancers. It directly delivers a high dose of radiation to the tumour, which has the benefit of a limited dose to the surrounding normal tissues.

• Radioactive implants (brachytherapy) Internal radiotherapy implants are radioactive metal wires, seeds, or tubes that are put into the body, near to or inside a tumour. The radioactive source is left inside the body, then removed after a short period ranging from minutes to days. During the time the source is in place, the patient must avoid close contact with people and may need to be cared for individually in the hospital. In some types of cancer, small metal implants (seeds) which contain radioactive gold or iodine are placed in the body permanently. These implants give a very high dose of radiation to cancer cells. For most types of implants, the radioactivity cannot be detected outside the body, as it can only travel a very short distance through body tissues – however, in some cases it may be detectable initially. Patients need to avoid close contact with people until the radioactivity drops to safe levels.

• Radioactive liquids Radioactive liquids to treat cancer are given either as a drink or by injection. The isotope is the radioactive part of the liquid, and may be carried by another substance which can take the isotope directly to the tumour. The particular liquid used depends on the type of cancer.

  • Radioactive phosphorus Used for blood disorders.

  • Radioactive radium or strontium Used for cancer that has spread to the bones (secondary bone cancer).

  • Radioactive iodine Used for thyroid cancers and conditions.

Side-effects of radiotherapy

Side effects vary depending on the part of the body being treated. Reactions can also change from one period of radiotherapy to the next.

• Fatigue As the body requires a lot of energy to manage and repair the effects of radiation on normal cells, tiredness and fatigue are common side effects. It is most prevalent towards the end of the treatment course, and can last for up to a few months after the course finishes.

• Skin Problems Skin surrounding the treatment area may become dry and itchy, looking red or sunburnt. In addition, some of the radiation passes entirely through the body, so skin on the other side of the body may also be mildly affected. Creams or dressings can alleviate discomfort and encourage healing.

• Mouth Problems Radiotherapy often causes side effects in the mouth and teeth, as it is often used to treat mouth, throat, or neck cancers. Effects may include difficulty in eating and swallowing, an affected sense of taste, a dry or sore throat, and a hoarse voice. Possible dental side effects include a higher risk or tooth decay or other dental problems.

• Fertility Issues If radiotherapy treatment is given near the reproductive organs, the fertility of both men and women can be affected. In women, radiotherapy around the pelvic area can cause changes to the menstrual cycle, including irregular periods. Some women will experience menopause (permanent stop of periods) as a result of the radiotherapy. In men, Radiotherapy to the area around the testicles may temporarily reduce sperm production.

• Other side effects include appetite loss, hair loss, nausea, or diarrhoea.

Immunotherapy

Immunotherapy is a relatively new type of cancer treatment, which uses the unique abilities of the immune system to potentially provide effective and long-lasting cancer treatment.

Monoclonal antibodies

Our body’s immune system attacks foreign substances using antibodies, which are special proteins produced by immune cells. Each antibody is specific for one type of antigen – antigens can be any number of proteins or other particles, and can include any foreign substances that have entered the body. Antibodies travel around the body in search of these antigens, and if they find their specific antigen, they will bind to it and alert other parts of the immune system: the foreign substance can then be destroyed if necessary.

Monoclonal antibodies (mAbs) are designed and created by researchers in the lab, and are able to specifically target a certain desired antigen – for example, an antigen only found on cancer cells. The target antigen must first be identified, and then specific mAbs can be designed, then created in large numbers and given to the patient.

Types of monoclonal antibodies

There are three types of monoclonal antibodies: naked, conjugated and bispecific.

Naked monoclonal antibodies

Naked mAbs are the most common type used in cancer treatments, and work on their own, in contrast to other types which may be attached to other substances. Their actual mechanism of action can vary: most attach directly to antigens found on cancer cells, but some bind to “normal” antigens on healthy cells or free-floating in the body.

Naked mAbs, once bound to their specific antigen, will call on the body’s immune system to mount a response against the cancer cells. For example, the response might interfere with the cancer cell’s ability to grow by blocking some of its essential proteins; or, it might “mark” the cancer cell for destruction by the immune system. Overall, this causes the cancer cells to stop growing or die.

Conjugated monoclonal antibodies

Conjugated monoclonal antibodies are joined to another drug, toxin, or radioactive particle which is able to kill or destroy cancer cells. The mAb is used like a “homing device”, carrying these substances around the body until it finds the target antigen: the substance is then delivered directly to the targeted cancer cells. This method means that the damage to normal cells in other parts of the body is greatly reduced.

Bispecific monoclonal antibodies

These drugs contain parts from two different mAbs, allowing them to bind to 2 different antigens at the same time. Usually one mAb binds to the cancer cell and another binds to an immune cell. In this way, the cancer cells and immune cells are brought close together, which causes the immune system to attack the cancer cells.

Side effects of immunotherapy

Whilst monoclonal antibodies help our body fight cancer cells, they are still a foreign substance to our body. As such, they can cause side effects including: fever, weakness, chills, nausea, vomiting, diarrhoea, low blood pressure and rashes.

Despite this, compared with chemotherapy drugs, mAbs are less likely to have serious side effects since they target cancer cells more specifically – less damage will be done to the body’s normal cells.

Remission

After successful treatment, cancer may go into remission. Remission is a decrease or disappearance of the signs of cancer.

• Complete Remission The cancer can’t be detected on scans, X-rays, or blood tests, etc. Doctors sometimes call this a complete response.

• Partial Remission The treatment has killed some of the cells, but not all. The cancer has shrunk, but can still be seen on scans and doesn’t appear to be growing. The treatment may have stopped the cancer from growing. Or the treatment may have made the cancer smaller so that other treatments are more likely to help, such as surgery or radiotherapy. This is sometimes called a partial response.

• Stable Disease The cancer has stayed the same size or it may even have grown by a small amount.