Splenic Irradiation — When the Spleen Is Treated

Because the spleen itself has become the problem. In several blood cancers it enlarges until it presses on the stomach and the diaphragm, causing pain, early fullness and breathlessness. It can also trap blood cells so counts fall. Splenic irradiation aims a low dose at the organ to shrink it and ease those symptoms.

The spleen sits high on the left, tucked under the lower ribs. In health you cannot feel it. In chronic blood cancers it can grow until it fills much of the left side of the abdomen, and at that size it stops being a background finding on a scan and starts dictating how you eat, sleep and move.

Splenic irradiation is a local treatment for that local problem. It is external beam radiotherapy aimed at the spleen, given in small amounts, usually with symptom relief as the stated goal. It is not a treatment for the disease throughout the body. The treatment your haematologist has prescribed continues, and the two teams agree the timing between them.

This matters for how you judge it afterwards. Success here is not a blood report that returns to normal. It is being able to finish a meal, lie on your left side, or walk to the gate without the drag under your ribs. Decide with your radiation oncologist, before you start, which of those you most want back.

In many patients, yes. Easing pain, early fullness and abdominal pressure is the main reason it is offered. The improvement usually builds across the course and the weeks after it, not overnight. Where the spleen was pulling counts down, counts may recover as it shrinks. The benefit is often temporary.

The timing surprises people. Nothing much changes in the first week. The spleen reduces gradually as treatment accumulates, and the symptoms ease behind it. Most of the change people notice comes towards the end of the course and in the fortnight or so afterwards.

Be clear with yourself about what “temporary” means here. For a chronic blood cancer, the relief is usually measured in months. That is a real gain when eating and sleeping have become difficult, and it is also a reason your team will plan what happens next before the benefit runs out.

The response also varies from person to person, and your team cannot promise which way yours will go. What they can do is set a review point — a date a few weeks after the last sitting when you assess together whether the things that mattered to you have actually changed.

Blood counts are a separate story from symptoms. Where a large spleen was trapping cells, shrinking it can let counts climb. But treatment can also lower counts in the short term. Both can happen in the same course, which is why the blood tests continue after the sittings stop.

Splenic irradiation appears in NCCN guidance for myeloproliferative neoplasms as a palliative option for symptomatic splenomegaly, and that word — palliative — is used in its proper sense: treatment given to relieve a symptom, not treatment given because options have run out.

1. Joint review and decision. A radiation oncologist looks at the spleen on your latest scan, reads your blood reports and agrees with your haematologist that radiation is the right tool for this particular problem. This is where the goal is written down: which symptom you most want eased.
2. Planning scan. A CT scan is taken in the exact position you will be treated in, with small skin marks so the position repeats each day. Tell the team now if lying flat is uncomfortable, or if the fullness is worse after eating. Supports and appointment timing can both be adjusted.
3. Planning gap. The dose is shaped tightly around the spleen and kept away from the left kidney, the base of the left lung, the stomach and the bowel. The plan is checked before anything is delivered. This normally takes a few days.
4. The sittings, with blood tests alongside. Each sitting takes minutes and you go home the same day. Blood is checked regularly through the course, and the next sittings are confirmed, reduced or postponed depending on the result. Expect the plan to be adjusted; that is how this treatment is meant to run.
5. Review afterwards. A few weeks later you and your team look at the spleen, your counts and, most importantly, the symptom you started with. If relief fades months later, a repeat course is often a fair question to raise.

• Blood counts falling — the dose-limiting effect. Low white cells, low platelets or worsening anaemia is why counts are checked through the course and for weeks after it.
• Tiredness — common, builds through the course, then lifts. Plan a lighter few weeks rather than fighting it.
• Nausea and appetite loss — the stomach sits next to the spleen, so mild nausea is expected. It is manageable with what your team prescribes, and it settles once treatment ends.
• A dull ache on the left — the treated area can feel sore for a while. Tell your team if it is sharp, sudden or different from the ache you came in with.
• Nearby organs — the left kidney, the base of the left lung, the stomach and the bowel all sit close by. Keeping dose away from them is the single biggest job in planning this treatment.

Call 1800 202 8726 or go to the nearest emergency department now if you develop fever with shivering, sudden severe pain in the left upper abdomen or left shoulder tip, new breathlessness, or bleeding and unusual bruising. With counts that may be low, these are not next-appointment problems.

On the longer view, and this matters most if you are young: a second cancer arising in an irradiated area is described in NCCN and ASTRO survivorship guidance as an uncommon risk that rises with the number of years since treatment, and the low doses and small volumes used here keep it lower still. No specific figure applies to every patient. Ask your radiation oncologist what was treated and to what dose, and keep the written answer — decades from now, a follow-up team will want it.

One more question worth asking directly. Radiation reduces the spleen; it does not remove it. Whether your remaining spleen function is reduced enough to justify the infection precautions and vaccinations advised after surgical removal is a decision for your haematologist, and it is worth raising rather than assuming.

• Weekday trips, and a schedule that may change. Build in flexibility. Sittings get postponed when counts dip, and that is normal rather than a setback.
• Blood tests are part of the treatment. Keep every report in one place and carry it to each appointment. The next sitting is decided from it.
• Eat around the appointments. With early fullness and possible nausea, small frequent meals work better than three large ones, and a lighter meal before a sitting is easier.
• Costs, in writing, before you start. Cost depends on the number of sittings and the technique used. Ask for a written estimate and check what your insurance or scheme covers. Any figure quoted is indicative, as of August 2026.
• Keep the record for later. Ask for what was treated and to what dose, in writing. Younger patients especially will be asked for this by follow-up teams years from now.

• The spleen is one of several places lymphoma turns up outside the usual lymph nodes. Radiation for Lymphoma in Unusual Sites covers how those sites are treated.
• Where the disease involves the brain or spinal fluid instead, the approach changes completely — see Radiation for Lymphoma Involving the Brain and Spine.
• If the spleen is being irradiated as part of a conditioning plan rather than for symptoms, Radiation Before a Stem Cell Transplant explains that very different setting.
• For the closest parallel in another blood cancer — a low-dose course aimed at one problem area — read Radiation for Plasmacytoma and Myeloma Bone Lesions.
• For the full picture of how treatment is planned, delivered at NABH-accredited partner centres and coordinated by our team, see Radiation Therapy at CION Cancer Clinics.

Not sure whether your spleen is the reason you feel like this? Book a free consultation and a radiation oncologist will go through your scans and counts with you. Or call 1800 202 8726.