Monoclonal gammopathy of undetermined significance (MGUS) - 31 year followup of a community study

Background: When unselected healthy adults in the community have their seru m screened by cellulose acetate or paper electrophoresis, monoclonal gammop athy of undetermined significance (MGUS) may be found in 0.5-1%. Aim: To report upon a 31 year follow up of MGUS in a New Zealand community. Methods: Serum from 2192 subjects (82% of the adult population) of a New Ze aland town was collected in 1967 and subsequently screened by cellulose ace tate electrophoresis. Eleven of the 2192 (0.5%) were found to have MGUS. Cl inical correlation was sought in 1970 and subsequently to elucidate the und erlying cause. Results: Seven of the 11 patients have developed a haematological malignanc y Two have been diagnosed as having Wldenstrom's macroglobulinaemia, one ma lignant lymphoma and acute myelomonocytic leukaemia and four developed myel oma. Myeloma developed at one, nine, 23 and 25 years after the original scr eening. One myeloma patient and one patient with MGUS are currently alive a nd well, 31 years after discovery of their gammopathy. Conclusions: The incidence of MGUS in this community is only half that dete cted in a comparable study. The association with haematological malignancy in this study (64%) is considerably higher than that found in the Swedish s tudy (6%), possibly because of the longer follow up in New Zealand. MGUS sh ould not only be studied in depth at the time of its discovery, but needs v ery long term follow up as the underlying disease may not surface until the third decade.