What is light chain myeloma and how does it affect the body? Also, how much time does one diagnosed have left to live?

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A family member of mine recently got diagnosed and I’ve been trying to read up about it, but I’m not a science person and I just don’t get any of it. I’m too afraid to ask my family members because it might upset them to think about it.

In: 7

Light chain myeloma is a subtype of multiple myeloma, a cancer of plasma cells. Plasma cells are B cells that are specialized at antibody production; they are very effective at pumping out loads of them to discharge into the blood. In multiple myeloma, some population of those plasma cells has become cancerous.

Their ability to create normal, functional antibodies (which are made by linking two “heavy chain” proteins together, and then one “light chain” to the side of both heavy chains) is disrupted; instead, they just make single light+heavy chain molecules, which are referred to as “M proteins”. In the case of *light chain* multiple myeloma, they’re not even making heavy chains at all anymore, and just dumping lots of free-floating light chains.

These free light chains are useless at fulfilling the normal protective functions of antibodies, so the cancerous plasma cells are no longer making a functional antibody you used to have in your blood previously. Worse, though, the free light chains sort of clog up the kidneys and cause progressive damage there. Together with pain in the bones caused by invasive growth of plasma cells in the bone marrow, this makes kidney damage a common symptom.

5-year survival rate is about 75% if the disease is contained to a single clump of plasma cells somewhere in the bone marrow. Drops go about 50% if it’s spread further.

Source: summarized from [here](https://www.healthline.com/health/cancer/light-chain-myeloma). I have an MSc in immunology.