Do the lumps, the 2 irregular and 4 regular, involve both of her breasts or all of the lumps are situated just in her right one?
Does your mother feel pain, discomfort or tenderness in her breasts?
Breast cancer, usually appears as a single lump.
Lumps that are multiple in breasts are suggestive for benign lumps of fibrocystic breast condition.
Acctually, fibrocystic lumps can mimic breast cancer by their consistency (sometimes, fibrocystic lumps can be felt as hard lumps, like in most of the cases of breast cancer), and by the shape (lumps due to fibrocystic change are often described as "lumpy", with an apparently irregular shape)
If fibrocystic breast condition is the case, than your mother like most of the women with fibrocystic breast condition must be followed over time as if they all are at an increased risk for developing breast cancer.