If you have been advised radiotherapy for rectal cancer, you may have many questions:
“Will radiation hurt?”
“Will I have diarrhoea every day?”
“Will I lose my hair?”
“Why am I getting radiotherapy before surgery?”
“If I feel nothing during radiation, is it even working?”
These are common questions. Here are the answers.
1. Why am I getting radiotherapy before surgery?
For many patients with locally advanced or higher-risk rectal cancer, treatment before surgery can shrink the tumour, treat disease in the surrounding tissues and lymph-node areas, and improve local cancer control.
The aim may be to:
shrink the rectal tumour,
treat cancer cells in the surrounding tissues,
treat nearby lymph-node areas at risk,
and improve the chances of effective subsequent surgery.
When chemotherapy and radiotherapy are given together before surgery, this is called neoadjuvant chemoradiotherapy .
Nowadays, many patients receive both radiotherapy and systemic chemotherapy before surgery. This overall strategy is called Total Neoadjuvant Therapy (TNT).
Your exact treatment sequence depends on factors such as your MRI findings, tumour location and stage, lymph nodes, relationship of the tumour to surrounding structures, and your general health.
So please do not worry if another patient with rectal cancer receives a different sequence from yours.
2. What happens before my first radiation treatment?
Before treatment begins, you will usually undergo a radiotherapy planning CT scan , also called CT simulation.
This is not your actual treatment .
Think of it as the map we use to design your radiotherapy.
Using your planning CT together with your MRI, examination and other investigations, your radiation oncology team identifies:
the tumour,
surrounding areas at risk,
lymph nodes that may need treatment,
and nearby normal organs that should be protected as much as possible.
A personalised radiation plan is then prepared for you.
3. How many radiation sessions will I need?
There is no single schedule for every patient.
For long-course chemoradiotherapy, treatment commonly takes about 25–28 sessions over approximately 5–5½ weeks. Some patients may instead receive short-course radiotherapy, commonly 5 sessions. The appropriate schedule depends on the tumour, MRI findings and the overall treatment strategy.
Other patients may receive a short-course radiotherapy schedule , depending on their clinical situation and overall treatment strategy.
Your radiation oncologist will select the schedule appropriate for you.
Do not compare your number of radiation sessions with another patient's.
4. Will I also receive chemotherapy during radiotherapy?
Often, yes.
During long-course chemoradiotherapy, medicines such as capecitabine tablets or intravenous 5-FU may be given along with radiation.
In this setting, chemotherapy acts partly as a radiosensitiser —it helps make the cancer cells more sensitive to radiation.
Depending on your treatment strategy, you may also receive additional systemic chemotherapy before or after the chemoradiotherapy phase, particularly when TNT is being used.
5. What will I feel when the radiation machine is actually treating me?
Usually, nothing .
You will lie on the treatment couch in the position determined during planning. Imaging may be performed before treatment to confirm that you are positioned correctly.
The treatment machine may move around you.
But when the radiation beam is switched on:
You will not feel heat.
You will not feel electricity.
You will not feel radiation entering your body.
You will not feel the tumour being “burned.”
The radiation treatment itself is painless.
Some patients finish their first session and ask:
“Doctor, I felt nothing. Did I actually receive radiation?”
Yes.
Radiation produces biological changes inside the treated cells. You do not need to feel radiation for it to work.
6. If I feel normal after the first few sessions, does that mean radiation isn't working?
No.
Radiotherapy side effects usually do not appear immediately .
They tend to develop gradually over the following weeks because normal tissues within the treatment area can become irritated as the radiation course progresses.
Similarly, having very few side effects does not mean that your treatment is weak.
The severity of side effects is not a measure of how effectively the tumour is responding.
7. Will my bowel movements change?
They may.
During pelvic radiotherapy, you may notice:
more frequent bowel movements,
softer stools or diarrhoea,
increased gas or bloating,
abdominal cramps,
urgency to pass stool,
mucus,
soreness while passing stool,
or a feeling that you still need to pass stool even after going to the toilet.
This happens because the rectum and some nearby bowel can become temporarily irritated during treatment.
If your bowel movements increase significantly, tell your treatment team .
Dietary changes, adequate fluids and appropriate medicines can often help.
8. Will the skin around my anus become sore?
It can, particularly later in the treatment course.
The skin around the anus, buttock crease or other areas receiving radiation may become:
darker,
red,
itchy,
sensitive,
or sore.
Please follow the skin-care instructions provided by your radiation oncology team.
Before applying a new cream, powder, herbal preparation or home remedy to the treatment area, ask your treating team first.
9. Can radiotherapy cause urinary problems?
Sometimes.
Because the bladder and urinary structures are close to the rectum, some patients notice:
increased frequency of urination,
urgency,
or mild burning while passing urine.
Please report these symptoms.
A urinary infection and radiation-related urinary irritation can sometimes feel similar , so it is better to inform your doctor rather than assuming every urinary symptom is caused by radiation.
10. Will radiotherapy make me tired?
It can.
Fatigue may gradually increase as treatment progresses.
This does not automatically mean that your cancer is worsening or that your body is becoming weak.
Remember that several things may be happening simultaneously:
You are travelling for treatment almost every day, receiving radiation, sometimes taking chemotherapy, dealing with bowel changes and perhaps eating differently.
All of these can contribute to fatigue.
11. Can chemotherapy cause additional side effects?
Yes.
If you are receiving chemotherapy such as capecitabine along with radiation, additional symptoms can include:
nausea,
reduced appetite,
mouth soreness,
diarrhoea,
or redness and soreness of the palms and soles.
Not everyone develops these problems, and their severity varies considerably between patients.
Report troublesome symptoms rather than waiting for them to become severe.
12. Will I become radioactive after my radiation session?
No.
External-beam radiotherapy does not remain inside your body.
After treatment, you can normally:
go home,
sit with your family,
eat together,
and hug your children or grandchildren.
You are not carrying radiation home with you.
13. Will I feel radiation burning me?
No.
Radiotherapy does not feel like fire while it is being delivered.
Skin soreness that develops later is a gradual tissue reaction to treatment. It does not mean that you were physically being burned while lying on the treatment machine.
14. Will I lose all the hair on my head?
Not from pelvic radiotherapy.
Radiotherapy affects hair mainly in areas actually receiving a significant radiation dose.
Because rectal cancer radiotherapy treats the pelvic region , it does not normally cause scalp hair loss.
Some systemic chemotherapy regimens used during other phases of rectal cancer treatment can affect hair differently. That is separate from the effect of pelvic radiotherapy itself.
15. Is radiation damaging my entire body?
No.
Modern radiotherapy is carefully planned to deliver the prescribed radiation dose to selected areas while limiting unnecessary exposure of surrounding normal tissues.
Normal tissues near the treatment area may still receive some radiation, which is why side effects can occur.
But this is very different from radiation being distributed randomly throughout your body.
16. What if I have almost no side effects?
That can happen.
It does not mean that the radiation is ineffective.
One patient may develop considerable bowel symptoms while another receiving a similar treatment has relatively mild symptoms.
We cannot judge tumour response simply by the amount of diarrhoea, skin reaction or fatigue you experience.
More side effects do not mean better cancer treatment.
17. What happens after I finish radiotherapy?
Do not expect the tumour to disappear immediately after your final session.
Radiotherapy does not work like switching off a light.
Its biological effects continue after treatment has finished, and the tumour can continue responding during the following weeks.
Your next step depends on the overall treatment strategy.
You may undergo:
a recovery and response period,
additional chemotherapy as part of TNT,
clinical examination,
MRI,
endoscopic assessment,
and other investigations when appropriate.
For many patients, surgery will then be the next major step.
18. Does everyone need surgery after chemoradiotherapy?
Surgery remains a standard component of curative treatment for many patients, but there is an important exception in carefully selected cases.
Some patients have an exceptionally good response to neoadjuvant treatment, with no clinically detectable residual tumour on careful reassessment. This is called a clinical complete response (cCR).
In specialised settings, selected patients with a convincing cCR may be considered for a “watch-and-wait” strategy rather than proceeding immediately to surgery.
But watch and wait does not mean:
“The tumour looks smaller, so we can forget about surgery.”
It requires careful patient selection, appropriate assessment and strict long-term surveillance , because local tumour regrowth can occur and must be detected promptly.
19. When should I contact my oncology team urgently?
Do not quietly tolerate severe symptoms because you think:
“Radiation patients are supposed to suffer.”
Contact your oncology team if you develop significant problems such as:
severe or repeated diarrhoea,
inability to drink enough fluids,
persistent vomiting,
fever,
significant bleeding,
severe or worsening abdominal pain,
difficulty passing urine,
marked weakness or dehydration,
or severe skin soreness.
Treating side effects early is usually easier than waiting until you become dehydrated or exhausted.
20. What is the most important thing to remember about rectal cancer treatment?
Your treatment is a sequence, not a single event.
Depending on your individual treatment plan, that sequence may look something like:
Planning → Radiotherapy with chemotherapy → Additional chemotherapy and/or response period → Reassessment → Surgery or another carefully selected strategy
Each part has a purpose.
During your daily radiation sessions, nothing dramatic needs to happen.
You may lie on the treatment couch, hear the machine moving, feel absolutely nothing , get up a few minutes later and walk out normally.
That does not mean nothing happened.
Your treatment was still delivered according to your carefully prepared radiation plan.
So do not judge your radiotherapy by how much you can feel it.
What matters is accurate planning, correct treatment delivery, completion of the prescribed treatment, timely management of side effects and proper reassessment afterward.