Multiple myeloma - Introduction

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Figure 7.1 Improving survival in MM resulting from novel treatments. (This research was originally published in Blood ^[1] © the American Society of Hematology)

Figure 7.2 Osteolytic lesions in the skulls of 2 patientswith multiple myeloma.

Figure 7.3 Classification of MM based upon monoclonal protein production. (UK, MRC Multiple Myeloma trials).

Multiple myeloma (MM) is the 2^nd most common form of haematological malignancy after non-Hodgkin lymphoma. In Caucasian populations the incidence is approximately 35 per million, per year, it increases with age and there is a slight male preponderance. In the UK there are 3,000-3,500 new cases per year, almost 20,000 in the USA and 86,000 world-wide, with a median survival of 3 years ^[2]. At any one time, there are 10,000 to 15,000 patients with the disease in the UK and nearly 250,000 world-wide. For those who enter clinical trials, the median 5-year survival is approximately 50%. The incidence of MM in different populations is shown in Table 7.1. Furthermore, there is a slowly rising incidence and survival is increasing (Figure 7.1) ^[1][2].

Table 7.1. Annual age-standardised incidence of MM by location per million ^[3].

Diagnosis is based on the presence of excess monoclonal plasma cells in the bone marrow, monoclonal immunoglobulins in serum or urine and related organ or tissue impairment such as hypercalcaemia, renal insufficiency, anaemia or bone lesions (Chapter 25). Normal plasma cell content of the bone marrow is about 1% while in MM the content is typically greater than 30% but may be over 90%. Concentrations between 5-10% are equivocal since plasma cell distribution in MM may be patchy or there may be other causes for the plasmacytosis such as chronic infections. Identification of the monoclonal cells is preferably achieved using immunohistochemical staining for κ and λ light chains (Figure 3.5).

The osteolytic lesions of MM, classically seen in skull X-rays (Figure 7.2), are not a constant feature. Patients may have osteosclerotic bone lesions or no detectable abnormalities. Also, osteolytic lesions may occasionally be seen in other diseases.

The immunoglobulin classes of monoclonal proteins produced by the plasma cell clones reflect their normal frequency in the body. This is shown in Figure 7.3 and is based on more than 2,500 patients entered into the UK MRC multiple myeloma trials from 1980 to 1998.

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