Histopathology-derived modeling of prostate cancer tumor control probability: Implications for the dose to the tumor and the gland

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• 作者：Ghazaleh Ghobadi^a ; Jeroen de Jong^b ; Birgit G. Hollmann^a ; Baukelien van Triest^a ; Henk G. van der Poel^c ; Conchita Vens^a ; ^d ; Uulke A. van der Heide^a ; ^{u.vd.heide@nki.nl" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Prostate cancer ; Histopathology ; Radiobiology modeling ; Dose differentiation
• 刊名：Radiotherapy and Oncology
• 出版年：2016
• 出版时间：April 2016
• 年：2016
• 卷：119
• 期：1
• 页码：97-103
• 全文大小：1429 K

文摘

To evaluate the impact of GTV-CTV dose differentiation by simulating response of prostate patients to radiotherapy, considering histopathology of prostatectomy specimens.

Material and methods

Tumors’ cell numbers (N₀) and Gleason Scores (GS) were derived from histopathology of 25 specimens. Index lesions and tumors ⩾0.5 cm³ were considered GTV. Satellites <0.5 cm³ constituted the tumor load in the CTV. Each patient’s tumor control probability (TCP) was simulated using the linear quadratic model and considering the N₀ while assuming either a constant or GS-dependent α and β.

Results

19/25 patients had multi-focal disease. In 11 patients the CTV contained GS 4 + 3 or 4 + 4 tumors. Compared to the GTV, the CTV pathology was more favorable. For an α = 0.140 Gy⁻¹, a GTV dose of 79 Gy with a CTV dose of 72 Gy achieved an 80% TCP in the population. Varying α between 0.160–0.118 Gy⁻¹ with GS, a GTV and CTV dose of 80 Gy and 70 Gy also gave an 80% TCP.

Conclusions

Considering only N₀, our simulations suggest that a GTV-CTV dose differentiation of 7 Gy would not compromise TCP of the patient population. When assuming an increased radiosensitivity with lower GS, a further dose differentiation of 10 Gy might be feasible.