A data processing method for planning a medical treatment, wherein the method is concerned with the prediction of tumor growth and/or the development of metastasis in the brain of a current patient, comprising following steps performed by a computer: - acquiring reference patient data describing medical information on at least one reference patient at different times, generated by carrying out at least two examinations of the at least one reference patient at different times, including information on the tumor growth and/or the development of metastasis in the brain of the at least one reference patient, the reference patient data including a sequence of images over time of the at least one reference patient; - acquiring current patient data describing medical information on the current patient, generated by carrying out at least one examination of the current patient, which is of the same type of examination as carried out on the at least one reference patient, the current patient data including an image of the current patient; - determining, based on the reference patient data and the current patient data, the statistical probability of at least one future scenario of the tumor growth and/or the development of metastasis in the brain of the current patient wherein - reference patient data is selected, which is linked to the same or at least most similar status of progression of tumor growth and/or of development of metastasis as the current patient data, by cross-referencing a first image included in the selected reference patient data and assigned to a reference time with the image included in the current patient data by using elastic fusion, the elastic fusion being described by a transformation matrix; - the transformation matrix is applied to a second image included in the selected reference patient data and assigned to a time later than the reference time, to determine an image of the current patient describing the at least one future scenario of the tumor growth and/or the development of metastasis in the brain of the current patient. - acquiring reference patient data describing medical information on at least one reference patient at different times, generated by carrying out at least two examinations of the at least one reference patient at different times, including information on the tumor growth and/or the development of metastasis in the brain of the at least one reference patient, the reference patient data including a sequence of images over time of the at least one reference patient; - acquiring current patient data describing medical information on the current patient, generated by carrying out at least one examination of the current patient, which is of the same type of examination as carried out on the at least one reference patient, the current patient data including an image of the current patient; - determining, based on the reference patient data and the current patient data, the statistical probability of at least one future scenario of the tumor growth and/or the development of metastasis in the brain of the current patient wherein - reference patient data is selected, which is linked to the same or at least most similar status of progression of tumor growth and/or of development of metastasis as the current patient data, by cross-referencing a first image included in the selected reference patient data and assigned to a reference time with the image included in the current patient data by using elastic fusion, the elastic fusion being described by a transformation matrix; - the transformation matrix is applied to a second image included in the selected reference patient data and assigned to a time later than the reference time, to determine an image of the current patient describing the at least one future scenario of the tumor growth and/or the development of metastasis in the brain of the current patient. - reference patient data is selected, which is linked to the same or at least most similar status of progression of tumor growth and/or of development of metastasis as the current patient data, by cross-referencing a first image included in the selected reference patient data and assigned to a reference time with the image included in the current patient data by using elastic fusion, the elastic fusion being described by a transformation matrix; - the transformation matrix is applied to a second image included in the selected reference patient data and assigned to a time later than the reference time, to determine an image of the current patient describing the at least one future scenario of the tumor growth and/or the development of metastasis in the brain of the current patient.