When is radiation required?

Radiation Therapy is a treatment modality which uses ionising radiation (photons, electrons, protons, etc.) mainly to treat malignant tumours. The way that this is achieved is by aiming the radiation at the tumour. The radiation then causes DNA damage within the cancerous cells in order to take away the cell’s ability to divide, hence the tumour dies.

Radiation therapy is one of the most effective modalities we have in treating cancer. The other two major treatment modalities used to treat cancer are surgery and chemotherapy. Over 50% of people diagnosed with cancer will require radiation therapy as part of their treatment regimen.

So when should a person have radiation therapy?

Most commonly, radiation therapy is used with the intent of curing the cancer. Radiation therapy is a local treatment, very much like surgery, thus if a tumour is confined to a specific site, and the surrounding tissue is not highly sensitive to radiation, high doses of radiation can be focused on that area to destroy the tumour, with the aim of curing the cancer. In general, if a cancer has spread throughout the body, a systemic treatment, such as chemotherapy, hormonal or immunotherapy is needed to treat the whole body.

Different tumours react differently to treatments. For some tumours, chemotherapy is the most effective, such as for a lymphoma. In others, surgical resection provides the best chance of cure, and in many, such as cervical cancer treatment, radiation therapy is the most effective. This is because different tumour types have a different sensitivity to radiation therapy.

Sometimes radiation therapy is given to palliate the symptoms of cancer, even if cure with radiation therapy is not possible. Radiation is able to relieve cancer symptoms, such as pain or bleeding, with tolerable side effects. So, even if the tumour is widespread, radiation may be directed at certain spots to relieve symptoms, such as pain at a specific site.

Radiation treatments for cure are often not given in isolation, and most patients will get a combination of surgery and chemotherapy along with radiation therapy. For example, patients with a breast cancer who undergo a lumpectomy will often get additional radiation therapy to the breast, as this will reduce the chance of a recurrence in the breast, and sometimes chemotherapy if it is felt that there is a high risk of a recurrence outside the breast.

Other factors need to be taken into account to undergo these treatments include a person’s fitness and medical condition. Ultimately the decision of whether to undergo radiation therapy should be made as a group, between the oncologist, surgeon and patient.

Written by Dr Duverrn Ramiah.

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