Uveal melanoma: therapeutic consequences of doubling times and irradiation results; a review.
Thirty-six of 39 published calculated doubling times (Td's) of uveal melanomas appeared to be longer than 60 days. Metastatic death occurs 35-40 Td's after dissemination. The shortest interval between dissemination and metastatic death in individual patients may, therefore, be calculated as 35 x 60 days = 6 years; the interval may extend to 80 years. This suggests, that local therapy cannot influence the survival data within the first 7 post-therapeutic years, because almost all metastatic deaths within these 7 years are due to pretreatment dissemination. For that reason, the published comparative survival analyses after various therapies have within this period failed to show statistically significant death rates differences. Microscopically viable melanoma tissue has been noted in 215 of 231 histopathologically studied irradiated uveal melanomas. Observed mitotic figures 4-6 years after irradiation indicate retained reproductive integrity. This constitutes a--by enucleation avoidable--incremental risk for post-irradiation exponential growth and dissemination. The risk cannot become statistically manifest before a greater than or equal to 10-year follow-up period. Retained, generally poor, visual acuity in a small percentage of patients cannot balance the incremental risk/benefit ratio of irradiation. A few, at present justifiable, indications for radiotherapy on uveal melanomas are enumerated.
Manschot
W A
WA
Institute of Pathology, Erasmus University, Rotterdam, The Netherlands.
van Strik
R
R
D001918:Brachytherapy; D015353:Eye Enucleation; D006801:Humans; D008545:Melanoma / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy; D012307:Risk Factors; D015996:Survival Rate; D016896:Treatment Outcome; D014604:Uveal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy; D014792:Visual Acuity / Q000528:radiation effects