link.springer.com/article/10.1007/s40521-014-0021-1/fulltext.html#Sec2

]. However, treatment with CSA is associated with immunosuppression and other adverse effects such as renal toxicity and hypertension as well as the risk of opportunistic infections and development of secondary tumors or tumor progression. Therefore, CSA and other similar immunosuppressive agents are not prescribed routinely in patients with SM. In this regard it has to be mentioned that indolent SM is a premalignant condition that exhibits a low but measurable potential for malignant progression.

If you find the paper by the specialist this is the important bit