Lung shunting: why it can rule out Y-90 | CION Cancer Clinics

Lung shunting means some of the blood going into the liver tumour slips straight through to the lungs instead of stopping in the tumour. If too much would travel that way, the radioactive beads used in Y-90 would land in the lungs and could damage them, so the team either lowers the dose or chooses a different treatment.

Where the shunt comes from

Liver tumours, especially hepatocellular carcinoma (HCC, the cancer that starts in the liver cells), grow their own blood vessels in a hurry. Some of these vessels are badly built. They form short cuts that connect an artery to a vein without passing through the fine network where the beads would normally get trapped. Blood that takes this short cut reaches the heart and is pumped into the lungs within seconds.

Why it matters for Y-90 in particular

Y-90 radioembolisation, also called TARE, places tiny radioactive beads inside the tumour's arteries. The beads stay where they lodge and irradiate only what is close by. If a share of them escapes to the lungs, the lungs receive radiation they were never meant to have. Large tumours, tumours growing into the portal vein (the main vein that brings blood into the liver) and very blood-rich tumours are the ones most likely to show a high shunt.

Being ruled out of Y-90 does not mean being ruled out of treatment. The CION tumour board brings the mapping report back to the table and asks the same questions again: how big the tumour is, how well the rest of your liver works, and how fit you are.

The options most often discussed

TACE (chemoembolisation) uses a different kind of bead and does not rely on radiation, so a lung shunt worries the team far less. Focused radiation from outside the body, such as SBRT, can sometimes treat a tumour the beads cannot. Medicines that work through the bloodstream, such as immunotherapy combinations or targeted tablets, treat the cancer wherever it is and are given at CION centres. For a few people, treating the tumour first and repeating the mapping scan later is an option.

Who this page does not apply to

If you have been offered TACE, surgery or ablation and not Y-90, the lung shunt is not relevant to you. It is also not relevant to cancer that spread to the liver from the bowel; that pathway is covered in the colon cancer section. And if your mapping result was low, the shunt question is already settled.

It cannot tell you whether your shunt result is safe. The limits depend on the bead type, the planned dose, your lung health and the size of the liver being treated. Only the interventional radiologist and nuclear medicine physician who planned your treatment can do that sum.

It cannot tell you which treatment comes next

That depends on the whole picture, not on the shunt alone. The CION tumour board reviews the scans, the mapping report and your liver blood tests together before suggesting a plan. Y-90 itself, the mapping visit and any other procedure are carried out through accredited partner hospitals, and your team will tell you where.