What is graft-versus-host disease?

Graft-versus-host disease, or GVHD, is when white blood cells from your donor treat your own body as foreign and attack it. The donated cells are the graft. You are the host. It can damage the skin, liver, intestines, and many other organs, and it can be life threatening.

It happens only after an allogeneic transplant, meaning one that uses cells from another person. It does not happen when you receive your own cells in an autologous transplant, because there is nothing for the immune system to read as foreign.

How likely it is

The odds turn on the match. Before a transplant, tissue from possible donors is tested against yours, and a closer match means GVHD is less likely or milder.

MedlinePlus puts the risk at roughly 35% to 45% when the donor is a relative, and roughly 60% to 80% when the donor is unrelated. Those are high numbers, and they are worth having before you consent, because they change how you plan the year after transplant.

Acute and chronic, and a live disagreement on timing

Doctors split GVHD into acute and chronic forms. The two behave differently, and the sources do not draw the line in the same place.

NCI states that acute GVHD occurs within the first three months after transplant, and chronic GVHD three months after transplant or later. MedlinePlus, reviewed more recently, says acute GVHD usually happens within days but can appear as late as six months out, and that chronic GVHD usually starts more than three months after transplant and can last a lifetime. So the two overlap in the three-to-six-month window. In practice, doctors now classify by what the symptoms look like as well as by the calendar. If you are told you have one form or the other, ask which features led to that call.

Acute GVHD mainly hits the skin, liver, and intestines. Watch for a skin rash with redness and itching, belly pain or cramps, nausea, vomiting, diarrhea, and yellowing of the skin or eyes, which is jaundice. Infections become more likely too.

Chronic GVHD is broader and slower. It can bring dry or burning eyes and vision changes, dry mouth with white patches and sensitivity to spicy food, joint pain and stiffness, skin thickening, shortness of breath from lung damage, fatigue and muscle weakness, weight loss, vaginal dryness, brittle hair, and early graying.

Contact your transplant team right away for any of these, or for any unusual symptom. Do not wait for a scheduled visit.

Lowering the risk, and treating it

Three approaches reduce the chance. The first is the match itself: the closer the donor's cells are to yours, the lower the risk. The second is medicine that suppresses your immune system, given routinely after transplant. The third is treating the donated cells to remove the T cells that drive the attack, a step called T-cell depletion.

Treatment usually starts with steroids such as prednisone, along with other drugs that damp down the immune system. Newer targeted therapies are also used. You stay on these until your transplant team judges the risk to be low, and you will have regular blood tests, because many of these drugs can harm the kidneys and liver.

One hard truth sits underneath all of this. The same donor cells that attack your tissue also attack leftover cancer cells, an effect NCI calls graft-versus-tumor. Suppressing GVHD completely would give up part of the transplant's benefit, which is why the goal is control rather than elimination. Our overview of stem cell transplant explains the transplant types, and the guide to infection and neutropenia covers the infection risk that comes with immune suppression.

Sources

• https://www.cancer.gov/about-cancer/treatment/types/stem-cell-transplant
• https://medlineplus.gov/ency/article/001309.htm