Starting radiotherapy can sometimes be confusing.
You may have already completed several radiation sessions and still be wondering:
“Why is my swelling still there?”
“Why has my pain increased?”
“Why don't I feel better yet?”
“Is my radiotherapy actually working?”
These are very common questions.
The important thing to understand is that radiotherapy does not work like surgery . The tumour may take time to respond, and sometimes you may notice treatment-related side effects before you notice its benefit.
Here are some common questions patients ask.
1. Doctor, I have already taken several radiation sessions. Why is my tumour still there?
Because radiotherapy does not physically remove the tumour.
During surgery, the surgeon physically removes the tumour and sometimes surrounding tissue or lymph nodes. Therefore, the physical change can be relatively immediate.
Radiotherapy works differently.
Radiation damages the tumour cells, particularly their DNA, so that they can no longer continue multiplying successfully. These damaged cells subsequently die or lose their ability to reproduce, and the tumour may gradually shrink or become inactive.
This takes time.
Therefore, do not expect every tumour to disappear after the first radiation session, after five sessions, or even necessarily by the day you complete treatment.
Depending on the type of tumour, its response can continue for weeks or months after radiotherapy is completed.
2. If my radiotherapy is working, shouldn't I already feel better?
Not necessarily.
You may sometimes notice the side effects of treatment before you notice improvement from the tumour.
Radiotherapy is carefully targeted, but normal tissues within or close to the treatment area can also temporarily become irritated or inflamed.
The side effects depend greatly on which part of your body is being treated, the radiation dose and schedule, the volume being treated, other treatments such as chemotherapy, and your individual health.
Depending on the treatment area, possible side effects may include:
tiredness
skin redness or soreness
mouth or throat soreness
pain or difficulty swallowing
dry mouth or altered taste
nausea
loose motions
urinary burning or frequency
local swelling or tenderness
temporary worsening of pain
You will not necessarily experience all of these.
Your treatment side effects and your tumour response do not always happen at the same speed.
Therefore, feeling uncomfortable during radiotherapy does not automatically mean that your cancer is progressing.
3. My pain has increased after starting radiation. Does that mean my cancer is growing?
Not always.
Pain can sometimes temporarily increase during or shortly after radiotherapy.
A well-known example occurs when radiotherapy is given for painful cancer deposits in bone. Some patients experience a temporary pain flare before longer-term pain relief develops.
Temporary inflammation or swelling in or around a treated area may also make certain symptoms feel worse for a short period.
So remember:
More pain does not automatically mean more cancer.
However, worsening pain should still be reported to your radiation oncology team.
Your doctor needs to determine whether it represents an expected treatment reaction or whether another problem needs investigation or treatment.
4. My swelling or lump has not reduced yet. Does that mean radiotherapy has failed?
No. Not necessarily.
Different tumours shrink at different speeds.
Some tumours respond relatively quickly, while others take weeks or months.
In addition, treatment-related inflammation can occasionally contribute to temporary swelling.
That is why repeatedly looking at or feeling a lump every day is not a reliable way of deciding whether radiotherapy is working.
Your oncologist will assess your response at the appropriate time.
5. Why can the side effects appear before the tumour shrinks?
Because tumour tissue and normal tissue do not respond in exactly the same way or on exactly the same timeline.
While tumour cells are accumulating radiation damage, normal tissues within the treatment area can temporarily become inflamed.
This creates a situation that can understandably seem confusing:
You may feel the treatment before you can see the result.
For example, during head-and-neck radiotherapy, the mouth or throat may become sore before a patient notices substantial reduction in the tumour.
This does not by itself mean that treatment has failed.
6. Does radiotherapy stop working after my last radiation session?
No. The biological effects of radiotherapy continue after the final treatment.
Your last radiation session does not represent your final tumour response.
Cancer cells that have already sustained radiation damage may continue to lose their ability to divide and die during the following weeks or months.
This is why the appearance of the tumour on the last day of treatment is not necessarily its final response.
7. Then why doesn't my doctor immediately order a CT scan, MRI or PET-CT after radiotherapy?
Because the best time to assess response depends on the type of cancer and the treatment you received.
Soon after radiotherapy, the treated area may contain inflammation, swelling and healing changes. In some situations, very early imaging may therefore be difficult to interpret or may not yet show the full treatment response.
Depending on your cancer, response may eventually be assessed using:
clinical examination
improvement in symptoms
CT scan
MRI
PET-CT
endoscopy
blood investigations
tumour markers
There is no single correct scan timing for every cancer.
Your oncologist will decide which investigation is appropriate and when it should be performed.
8. Another patient's lump disappeared quickly. Why is mine taking longer?
Because every tumour is different.
The person sitting next to you in the waiting area may have a completely different disease.
Differences can include:
cancer type
stage
tumour size
tumour biology
treatment site
radiation dose and schedule
chemotherapy or other treatments
overall health
purpose of treatment
Some cancers are particularly radiation-sensitive and may shrink relatively quickly. Others respond much more gradually.
A fast visible response does not automatically mean a better final outcome, and a slower response does not automatically mean treatment failure.
Your response should be judged according to your disease and your treatment plan , not someone else's.
9. What if I am receiving radiation for a benign tumour?
Radiotherapy is occasionally used for selected non-cancerous or benign tumours as well.
In some of these conditions, the aim of treatment may not be to make the tumour completely disappear.
Instead, successful treatment may mean:
The tumour stops growing and remains controlled.
For example, some benign intracranial tumours can remain visible on MRI for years despite successful treatment.
After stereotactic radiation or radiosurgery, certain tumours — such as some meningiomas or vestibular schwannomas — may also temporarily enlarge because of treatment-related changes before subsequently stabilising or decreasing.
This is sometimes called transient enlargement or pseudoprogression .
However, this does not occur with every benign tumour , and an enlarging tumour should never automatically be assumed to represent pseudoprogression.
Your oncologist must interpret the scan according to the particular tumour, treatment technique, timing and your symptoms.
10. If surgery removes the tumour immediately, why don't we operate on every cancer?
Because the fastest way to physically remove a tumour is not necessarily the best treatment for that particular cancer.
Treatment is selected according to factors such as:
cancer type
cancer stage
tumour location
whether complete surgery is possible
nearby important organs and structures
your overall health
possible effects of surgery on speech, swallowing, appearance or organ function
whether radiotherapy can preserve an organ or its function
whether chemotherapy or another systemic treatment is required
expected long-term cancer control
For some cancers, surgery is the preferred treatment.
For others, radiotherapy or chemoradiotherapy can provide an excellent chance of control or cure while avoiding major surgery or preserving an organ.
And very often, surgery and radiotherapy are not competing treatments at all .
A patient may need both at different stages of the same treatment plan.
11. Should I judge whether my radiotherapy is working by how I feel every day?
No.
During several weeks of radiotherapy, you may have better days and more difficult days.
You may feel tired.
Your skin may become sore.
Your mouth or throat may hurt.
Swallowing may become uncomfortable.
Your pain may fluctuate.
These daily symptoms are not a reliable test of whether radiation is controlling the cancer.
Radiotherapy is delivered according to a carefully planned dose and schedule, and treatment response is assessed at the medically appropriate time.
12. When should I contact my radiation oncology team?
Although many side effects during radiotherapy are expected, never assume that every new or worsening symptom is simply “because of radiation.”
Contact your treating team promptly if you develop symptoms such as:
severe or rapidly worsening pain
inability to eat or drink adequately
repeated vomiting
significant bleeding
fever
difficulty breathing
rapidly increasing swelling
new weakness or numbness
difficulty walking
confusion or unusual drowsiness
new loss of bladder or bowel control
Depending on the area being treated and your individual condition, your oncology team may give you additional warning signs to watch for.
13. So, Doctor, how will we know whether my radiotherapy has worked?
Your oncologist will assess the response using the methods appropriate for your particular disease.
This may include:
your symptoms + clinical examination + appropriate investigations.
Some tumours respond within weeks.
Some take months.
Some slow-growing or benign tumours may take much longer.
And sometimes successful radiotherapy means long-term control rather than complete disappearance of the tumour.
The Most Important Thing to Remember
With radiotherapy, you may notice the side effects before you notice the benefit.
Your tumour does not have to disappear immediately for radiotherapy to be working.
So if you are midway through treatment and wondering:
“Doctor, I don't feel better yet. Is my radiation working?”
Do not judge the entire treatment by how you feel today.
Take your supportive medicines as prescribed, report significant or worsening symptoms, complete your treatment according to your oncology team's advice, and attend your scheduled follow-up.
Your last radiotherapy session may be the last day you enter the treatment room — but the biological effects of your treatment can continue afterwards.