Radiotherapy For Lung Cancer

Figure 1: Typical equipment of radiation

Focussing rays on a lung cancer kills the cells and this form of therapy has become standard to treat lung cancers at various stages of progress. Generally speaking, radiation is not as successful as surgical removal, but often for one reason or another, such as poor respiratory function, heart disease, etc..., some patients with lung cancer cannot undergo an operation. Radiation given in this context is called Curative intent radiation. If a cancer has progressed to be beyond surgical removal either because of local spread or spread throughout the body, radiation has a role in treating symptoms and is given as a palliative form of therapy. Radiation however has one advantage and that is it can be focussed in areas often unapproachable by surgery and if surgery is not possible for technical reasons radiation can prove of significant benefit.

In Melbourne, radiation is only given in special centres. The radiation given is called Megavoltage radiation and is an X ray of 4 to 18MeV. Standard radiation is set between 6 and 10 MeV which is the safest setting for minimising scattering from secondary neutrons in the room which can endanger staff.

Figure 2: Planning treatment method

The rays can be focussed on the cancer and using the CT planning scans, contours are constructed around the cancer, optimising radiation to the cancer whilst minimising exposure and radiation effect on the spinal cord, oesophagus, heart, etc...

Radiation, whilst killing cancer cells also has an effect on the lung, scarring it and making it less elastic. This can cause a cough, and changes of scarring on the lung can be seen after a while, on the CT of the chest as white lines radiating out from the radiated area.

Visits for the radiation are split up so that the total dose of radiation is divided up usually into 2 Grey per fraction (dose), so that it usually takes 5 to 6 weeks having radiation 5 days a week to complete the treatment. Each treatment lasts 1 minute or less, and the room is fairly quiet with no great noises or unexpected happenings.

The area to be irradiated is marked on the skin with a purple indelible pencil and each day these markings are used to realign the machines rays.

Radiation effect can be likened to a bad sunburn, with a feeling of being off food and feeling sick increasing as the time moves on. However the effect wears off after treatment stops. There may be a mark like a sunburn left on the skin after the treatment and some moirturising cream may be needed if the skin is dry or itchy.

After treatment, evaluation is done in a follow-up clinic to assess the effect. The X ray would usually show a shadow still, because the radiation does not make it disappear, rather kills the cancer cells and creates a scar in its place.