Italian external and multicentric validation of the MD Anderson Cancer Center nomogram and prognostic index for chronic lymphocytic leukaemia patients: analysis of 1502 cases

We performed an external and multicentric validation of the nomogram and prognostic index (PI) proposed by the MD Anderson Cancer Center to prognostically stratify chronic lymphocytic leukaemia (CLL) patients in 1502 CLL cases. All six parameters involved in the nomogram and PI (age, sex, absolute lymphocyte count, number of lymph node groups, Rai stage and 2-microglobulin) were independently associated with survival. The nomogram was accurate in predicting survival (c-index=082). According to the PI, 387% of patients were at low-risk, 583% at intermediate-risk and 3% at high-risk. The estimated median survival times were: not reached for low-risk, 134years for intermediate-risk and 34years for high-risk. The estimated median and 5-year survival by PI were similar to those originally reported. The PI remained a predictor of survival when analysis was limited to 847 Rai stage 0 (P<00001) and 151 clinical monoclonal B-cell lymphocytosis (cMBL) cases (P=0033). Finally, the PI allowed prediction of time to therapy in all patients (P<00001), in Rai 0 (P<00001) and in cMBL cases (P=0044). Our results confirm the ability of the PI to predict prognosis, even in early stage disease cases. The study also extended the utility of the PI to cMBL cases.