Radiation Therapy for Unknown Primary Cancer
For Cancer of Unknown Primary, radiation therapy may be used to treat the lymph nodes affected by cancer with or without the primary site(s) that it may likely have come from. The most common approach for cancer of unknown primary is called external beam radiation. This is where the radiation is applied from outside of the body.
Radiation therapy can be used in the following ways:
This is when radiation therapy is used on its own without surgery. Definitive radiation therapy may be targeted to one side of the neck area (unilateral), containing the cancerous lymph nodes, or both sides of the throat (bilateral) to treat all possible areas of primary cancer. Typically, radiation therapy is delivered daily (but not on weekends) over 7 weeks. Chemotherapy may be added to the radiation therapy (chemoradiation)
This is when radiation therapy is given after surgery and is used as an additional treatment to kill any cancer that may not have been removed during surgery. Adjuvant radiation therapy may also be given in combination with chemotherapy (called chemoradiation).
In cases where a cure is not possible, radiation therapy is used to relieve symptoms of advanced cancer of unknown primary. Symptoms that may require palliative radiation therapy include pain, bleeding, breathing and swallowing difficulties.
How do I prepare for Radiation Therapy?
You will meet with many members of the cancer care team, who will help you learn how to look after yourself through radiation therapy, recovery and long term follow-up. They will also talk to you about side effects and how to manage them. It may be helpful to write down questions as they come up, so you can ask anyone in your cancer care team when you see them.
Radiation Therapy Mask-Making and Simulation
- Radiation therapy is a precise treatment. In order to make sure, that the cancer is covered by the treatment, you will need to be very still during the treatment, usually for about five minutes. A radiation therapy mask that is made to fit perfectly to your shape, will be put on you during each treatment to help the machine target where the cancer is.
- You will have a planning CT scan (and sometimes other scans) with the mask on. Your radiation oncologist and radiation therapists will use these scans with all your other clinical information to develop a radiation therapy plan just for you (a personalised plan). Your plan will be checked by the radiation therapy and radiation oncology physics team before it is ready to be used for your treatment. This whole process can take approximately 2-3 weeks.
Teeth and Mouth Care
You might need to have some of your teeth taken out, this will depend on the area being treated and the dose of radiation therapy. It is important to take out any broken or infected teeth before radiation therapy. Taking out unhealthy teeth after radiation therapy can cause problems with the jaw bone. Further information about removing teeth and what to expect before and after the operation is available here.
Diet and Nutrition
Your cancer and its treatment can make it hard to eat and drink. Your doctor will recommend you see a dietitian to maximise your nutrition during treatment as well as while you are recovering. Sometime feeding tubes may be recommended depending on the area being treated and the dose of radiation therapy.
There are two common types of feeding tubes:
- Gastrostomy tube (sometimes called a PEG tube): this type of tube is inserted through your abdominal wall into your stomach, with part of the tube staying outside the stomach. A syringe can be attached to the tube to give you food this way if needed. The tube is inserted using a camera through the mouth into the stomach (gastroscopy) or using a CT scanner to guide insertion directly through the skin. If a PEG tube is needed, your doctor will organise this before starting your radiation therapy.
- Nasogastric tube: this type of tube goes through the nose down into the stomach and is usually used for short periods (days or weeks). A nasogastric tube can be inserted at any time (before, during or after treatment).
Speech, Voice and Swallowing
Your cancer and its treatment can make swallowing and speech difficult. Your doctor will recommend you see a speech pathologist, who can help you with ways to manage swallowing and communication difficulties, during and after treatment.
There are many other aspects of supportive care that are available, ask your doctor if you have any specific needs.
The side-effects of radiation therapy start around two weeks into treatment and progress through treatment to peak in the last week or just after treatment ends. The side effects start to improve 2-3 weeks after the end of treatment.
Side effects associated with radiation therapy depend on:
- the dose of radiation therapy
- the area being treated
- whether or not chemotherapy is added to the radiation
Each individual responds to radiation therapy differently. Some people may experience a few side effects while others may not experience any at all.
The following are some common side effects of radiation therapy:
- skin irritation in the treated area e.g. redness, dryness and itching, weeping skin, scaling or sometimes skin breakdown (sores)
- dry mouth and throat due to lack of saliva (called xerostomia)
- ulcers in the mouth or throat that make it painful or difficult to chew or swallow
- altered taste, which is usually a loss of taste or sometimes an unpleasant taste in the mouth
- pain on swallowing or difficulty with swallowing.
Most side effects are short lived and may go away within 4–6 weeks of finishing radiation therapy. Some side effects may last for months after you finish radiation therapy and some may be permanent.
Once your radiation therapy ends, you will have regular follow-up appointments so your cancer care team can check your recovery and monitor any side effects that you may have. Your doctor may recommend some specific supportive care options to help during your recovery, such as help with changes in diet, teeth and mouth care and speech or swallowing
Chemotherapy for Cancer of Unknown Primary
Chemotherapy works by destroying or damaging cancer cells. For head and neck cancers, chemotherapy is usually given into a vein through a needle with a catheter (tube) attached.
Usually chemotherapy is used in combination with radiation therapy to make the radiation therapy more effective. It is usually given once a week or once every 3 weeks throughout the duration of radiation therapy. Unlike chemotherapy for many other cancers, most patients do not lose their hair or have severe nausea and vomiting.
The side effects of chemotherapy depend on the medication used and how much you are given by your doctor (the dose). The most common medications used are called cisplatin, carboplatin and cetuximab.
Each person responds to chemotherapy differently. Some people may experience a few side effects while others may not experience any at all.
The following are common side effects of chemotherapy:
- nausea and vomiting
- loss of feeling in the fingers and toes
- some medications may cause kidney damage
- hearing loss/thinning
- ringing in the ears
- higher risk of infection (if the chemotherapy reduces the number of white cells in the blood)
Most of these side effects are short lived and may go away once you finish chemotherapy. Some side effects can take months or years to improve or may be permanent.
Once your treatments end, you will have regular follow-up appointments so that your doctor can check your recovery, make sure the cancer has not returned and monitor and treat any side effects that you may have.