In the radiotherapy of prostate cancer, technique determines the doses to the penile structures

For 11 consecutive prostate cancer patients undergoing three-dimensional co nformal radiotherapy (3DCRT) in our institution, penile structures (PNS) we re outlined in CT images obtained for treatment planning purposes. Dose-vol ume histograms (DVHs) were compared in order to study dose-volume relations for three techniques: 4FLD, an axial coplanar, four-field box technique; 6 FLD, a six-field coplanar technique; and 4NAX, a coplanar but non-axial, fo ur-field technique. All three techniques delivered equal doses to the plann ing target volumes (PTV). Our statistical analyses strongly indicate that t he three techniques can be ranked as GFLD better than 4FLD (and 4FLD better than 4NAX) as far as irradiating PNS volume during treatment of prostate c ancer (PC) is concerned. For each technique, there is a "spread" owing to d ifferences in patient anatomy and/or target size, position, and extent, but each technique has a similar "profile" or "shape" distinct from other tech niques. Whether irradiating smaller volumes of PNS will influence the sexua l potency outcome remains to be demonstrated. However, PNS should be consid ered as another critical structure in addition to rectum, bladder and femor al heads in the radiotherapy (RT) of PC, especially in 3DCRT dose escalatio n studies. Sexual potency outcomes can be correlated to dose-volume relatio ns in the future and this will help refine radiotherapy techniques further.