A preliminary study of low-dose splenic irradiation for the treatment of chronic lymphocytic and prolymphocytic leukaemias

21 patients, 18 with chronic lymphocytic leukaemia (CLL) and 3 with prolymphocytic leukaemia (PLL), all B-lymphocyte origin and with progressive disease, were treated with a regime of low-dose splenic irradiation (SI). All patients experienced a rapid relief of disease-related symptoms. Following SI the total lymphocyte count (TLC) was markedly reduced in 18 patients. Partial to complete regression of splenomegaly occurred in 9 patients. Pre-existing anaemia of production failure type improved in 6 patients and as a result the haemoglobin rose to normal or near normal levels. SI caused the loss of T-, B- and Null-lymphocytes, but the loss of B-lymphocytes predominated. CLL/PLL became quiescent for long periods in 9 patients (CLL = 8; PLL = 1) but remained progressive in the other 9, all CLL. SI had no demonstrable effects on TLC, splenomegaly or anaemia in the 3 remaining patients (2 CLL, 1 PLL). The treatment was well tolerated by all, and side effects were almost absent. Transient reduction of neutrophils and platelets occurred commonly. No patient with initially normal neutrophil and platelet counts developed irreversible neutropenia or thrombocytopenia. In view of these effects, the ease of administration and the lack of side effects, further evaluation of low-dose SI, particularly in comparison with other regimes, seems worthwile.