Time course, clinical pathways, and long-term hazards risk trends of disease progression in patients with classic mycosis fungoides: A multicenter, retrospective follow-up study from the Italian Group of Cutaneous Lymphomas

BACKGROUND: Mycosis fungoides (MF) is an indolent primary cutaneous T-cell lymphoma. To the authors' knowledge, no data currently are available regarding the evolution over time of the risk of developing specific pathways of disease progression. METHODS: This retrospective study analyzed 1422 patients with MF who were diagnosed and followed from 1975 through 2010 in 27 Italian Study Group for Cutaneous Lymphoma centers. The primary objectives were to ascertain the time course, pathways, and hazards risk trends of cutaneous/extracutaneous disease progression; to evaluate whether different tumor-lymph node-metastasis-blood (TNMB) stages have different pathways of disease progression; and to analyze differences between tumor-stage and erythrodermic MF with regard to clinical onset, disease evolution, and prognosis. The secondary objective was to provide a further validation for the revised International Society for Cutaneous Lymphomas and the Cutaneous Lymphoma Task Force of the European Organization of Research and Treatment of Cancer (ISCL/EORTC) classification. RESULTS: The median follow-up was 14.5 years; stage progression occurred in 29.7% of patients and blood involvement was the most frequent extracutaneous site of disease progression. Patients with stage IA to stage IB disease demonstrated a steady low annual incidence of disease progression to tumor-stage (1%-2%); patients with stage IIA disease had a higher risk within the first years (up to 9.4%). Erythroderma evolved with a significantly higher frequency from patches/plaques (13.9%/28.2%) than tumors (P =.028 and P =.013, respectively). Hazards rates of extracutaneous involvement were low (<1%). The T-score was found to be associated with extracutaneous involvement site, tumor-stage disease with lymph node/visceral lesions, and erythroderma with blood involvement. TNMB classification and stage progression resulted as independent prognostic variables being detected on multivariate analysis; the type of extracutaneous involvement was found to affect survival. CONCLUSIONS: The data from the current study support the need for a stage-tailored follow-up, suggest that the classification of tumor-stage disease at a stage below erythroderma could be modified, and offer a further validation for the revised TNMB classification.