[i]Familial[/i] means there has been some evidence of it "being in families", but we don't yet know why. So far, researchers have failed to find a specific gene that leads one to get MM, but that's not to say there couldn't be a genetic component.
From Cancer Research UK:
[i]A small number of case-control studies have consistently found first-degree relatives (parent, sibling or child) of myeloma or monoclonal gammopathy of undetermined significance (MGUS) patients are two to three times more likely to develop myeloma or MGUS themselves, in comparison with people without a close family history of these conditions. It is currently unclear whether these links are due to shared genetic factors, shared environmental factors (first-degree relatives may be exposed to the same environmental or behavioural risks), or a combination of these.[/i]
Being "two to three times more likely" to get a cancer that is already rare is, as one doctor put it, "like being two to three times more likely to win the lottery". I get what he's saying, although I have mixed feelings about this way of putting it – it reassures relatives of MM patients that they shouldn't worry too much, but I know my mother's response to hearing about the general rarity of the cancer was something along the lines of, "Great, as usual I'm one of the unlucky ones."
