Background: Testicular intraepithelial neoplasia (TIN), synonymous for carcinoma in situ of the testis, is a rarely observed preinvasive neoplasia located within the germinative epithelium. According to the current knowledge of the biology of TIN, it is the common precursor of all testicular germ cell neoplasms except spermatocytic seminoma.
Material and methods: This report provides a review of histopathology, epidemiology and diagnostic procedures for TIN and discusses the therapeutic options with particular respect to radiooncological aspects.
Results: TIN has a 70% rate of progression to invasive cancer within 7 years. Depending on the individual therapeutic setting surgery, chemotherapy and radiotherapy are alternative treatment modalities. In case of TIN in a single testis or bilateral TIN, local radiotherapy is the standard procedure. With 20 Gy recommended as standard dose in Germany, radiotherapy yields safe eradication of TIN. However, some of the patients show significantly reduced synthesis of testicular androgens. With respect to sporadic reports in the literature, total doses well below 20 Gy might be equally efficient to treat TIN safely. Yet, up to date neither the minimum dose for efficient treatment nor the toxicity profile after consecutive chemo-radiotherapy has been established.
Conclusions: The currently recommended standard dose of 20 Gy in Germany is probably in excess of the minimum dose needed for safe eradication of TIN. Thus, new radiooncological strategies should aim at reducing the total dose of treatment in order to minimize late side effects while maintaining the high efficacy of radiotherapy. This topic is under investigation in a multicenter clinical trial.