Monoclonal proteinaemia and solid tumours

A higher prevalence of solid tumours in patients with M(onoclonal) proteinaemia without a co-existing haematological malignancy has been reported. We investigated this association by linking a population-based registry of patients with newly diagnosed M-proteinaemia (n = 1464) with the Regional Cancer Registry. Patients were followed for a median of 7.4 years for those still alive. In total 167 (11%) patients with 173 solid tumours were compared with 861 patients with 'M-proteinaemia only' (without a haematological malignancy). The M-protein isotype or level or clinical parameters did not differ between the groups. M-protein isotype was not associated with a specific tumour type. Standardised Morbidity Ratios (SMR) for nearly all solid tumours were elevated in the year of the M-protein discovery, but the excess risk disappeared during follow-up suggesting selection through diagnostic investigations rather than a causal role. In this large series of patients with both newly diagnosed M-proteinaemia and a solid tumour no relationship could be established.