This is the summary of a 2015 talk given to the Auckland Support Group by Dr Hedley Krawitz of Radiation Oncology, Auckland.
• The aim is to increase tumour control while minimising complications.
• Fractionation is important. Small doses each day builds up to a big dose overall which leads to better tumour control.
• Between treatments, there is some recovery of normal cells but tumour cells don't recover as well.
• The best total dose is between 60 to 70 grays.
Three ways of using radiotherapy
1. Definitive = radiation alone
3. With chemo
This depends on site, cosmetic aspect and function. Surgery is often used for oral and larynx cancers for example, while radiation is used for oropharyngeal and nasopharyngeal cancers.
Post-op is recommended if features indicate a risk of recurrence: close margins, more than one deposit, bone or nerve involvement, more than one lymph node involved, or extra nodal spread.
Decisions are made by the multi-disciplinary panel. Chemoradiation is for advanced cases. It controls the tumour more but is not for everyone because there are worse side effects.
(Two studies show improvement in tumour control with post-op chemoradiation.)
What is the evidence for the use of radiotherapy?
• Definitive radiotherapy for stage one cancers leads to a 90% tumour control rate. Post-op, it reduces risk of recurrence at primary site and in neck.
• The gold standard is a randomised study. If margins are clear there is only an 11% recurrence rate with radiotherapy. With surgery alone there is a 17 to 31 % rate of recurrence.
• There are other percentages for close margins and “involved” margins but overall radiotherapy reduces the rate of recurrence by 50 %.
How is RT administered?
• The mask is used to immobilise the head and neck - and for accuracy. People who suffer from claustrophobia find this unpleasant.
• A tongue depressor is used to protect some of the tissues in the mouth. This can be uncomfortable.
• Radiation used to cover a wide area but now with Intensity Modulated Radiation Therapy (IMRT), the dose conforms more to the tumour, while reducing the effect on the parotid glands for example (major salivary glands).
• They try to shield food pipe and voice box if possible.
• It is an intense treatment. Side effects can be described as "acute" or "late".
• One of the notable late side effects is the risk of bone damage if teeth are removed from irradiated bone.
• There are two treatments to prevent damage: hyperbaric oxygen treatment and PENTACLO which consists of Trental, Vitamin E and an antibiotic.
• Some other long term effects are chronic otitis media (fluid on the ear), hearing loss, swelling problems and hypothyroidism. The latter can be fixed with thyroid tablets.
RT has an important role to play by itself, with chemo, or after surgery. Post-op it reduces the risk of the cancer coming back. For select groups, chemo is needed as well. Early tumours can have radiation alone.
Is radiation carcinogenic?
Very small risk. Kills cancer cells better than it hurts normal cells. (Tumours escape the normal control of the body.)
Does Auckland use brachytherapy?
Brachytherapy is a method where the radiation is very close to the tumour as in inserting wires into it. Not used in Auckland for head and neck cancer because complications are worse than the benefits.
How can we deal with fluid in the ear?
Many people get this. It may clear by itself. Antibiotics can help. Can't use grommets because adult ears leak continuously when grommets are inserted.
How to cope with dry mouth?
Products you can buy work temporarily. Spray mouth with cooking oil. Butter in the cheek lasts longer than water. (Esther)
Why does scar tissue or fibrosis keep growing in some people?
Radiation affects the small blood vessels. The reaction of tissue without blood circulation is to scar.