RESUMO
BACKGROUND: Patients with mycosis fungoides (MF) tumour stage IIB disease show considerable variation in the number of tumours and time interval between each tumour occasion. OBJECTIVES: To quantify the extent of tumour formation in patients with stage IIB MF and correlation with survival. METHODS: The variability in tumour development of 46 patients with stage IIB MF was quantified by calculating a frailty score with the use of a statistical frailty model, based on both the number of tumours developed during follow-up and the time interval between each tumour occasion. The prognostic value of the frailty scores and the number of tumours at 6 and 12 months after first tumour development were studied. RESULTS: Frailty scores varied between 0·05 and 6·94. Patients with high frailties (> 1·0, n = 14) had the worst disease-specific survival (DSS) and overall survival (OS), compared with patients in the low frailty group (0-0·35, n = 17) and medium frailty group (0·35-1·0, n = 15). Differences in DSS and OS between the three frailty groups were highly significant (both P < 0·001). The number of tumours that developed within 6 months after the diagnosis of MF stage IIB was prognostic for subsequent DSS and OS (P < 0·001 and P = 0·021, respectively). CONCLUSIONS: The number of tumours and time interval between tumour formation differs greatly among patients with stage IIB MF and these differences correlate with survival. Patients with an adverse prognosis can be identified by quantifying the number of tumours that develop within 6 months after diagnosis of MF stage IIB.