Secondary cancers evaluation inside organs at risk 
during the prostate cancer radiotherapy: a brief report

Shamsabadi, Reza; Zoljalali Moghadam, Seyed Hamid; Baghani , Hamidreza; Zoljalali Moghadam , Seyed Ali

Volume 81, Issue 3 (June 2023) Tehran Univ Med J 2023, 81(3): 193-197 | Back to browse issues page

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Shamsabadi R, Zoljalali Moghadam S H, Baghani H, Zoljalali Moghadam S A. Secondary cancers evaluation inside organs at risk during the prostate cancer radiotherapy: a brief report. Tehran Univ Med J 2023; 81 (3) :193-197
URL: http://tumj.tums.ac.ir/article-1-12425-en.html

Secondary cancers evaluation inside organs at risk during the prostate cancer radiotherapy: a brief report

Reza Shamsabadi ^*

¹, Seyed Hamid Zoljalali Moghadam²

, Hamidreza Baghani¹

, Seyed Ali Zoljalali Moghadam³

1- Physics Department, Faculty of Science, Hakim Sabzevari University, Sabzevar, Iran.
2- Medical Physics Department, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran.
3- Electrical Engineering Department, Faculty of Electrical and Computer Engineering, Tarbiat Modares University, Tehran, Iran.

Abstract: (523 Views)

Background: In prostate cancer radiotherapy, due to the proximity of the prostate to the rectum, it can be affected by high radiation doses. It has been reported that about 70% of secondary cancers after prostate cancer radiotherapy occur in the bladder and rectum, which are exposed to direct radiation. Since prostate cancer radiotherapy may be accompanied by side effects, the aim of this study is to investigate the risk of secondary cancers after the radiotherapy of prostate cancer inside the outfield organs.
Methods: The dose volume histogram data relevant to 39 patients with prostate cancer (who were treated with 3-dimensional conformal radiotherapy technique in 2022 in Tehran) were extracted, and the uniform absorbed dose inside the sensitive tissues was calculated according to the gEUD concept. Then, the risks of secondary malignancies following prostate cancer radiotherapy were calculated using the model introduced by the BEIR report. Accordingly, the lifetime attributable risk values (LAR) were estimated based on the desired organs and patient age at exposure time through the calculation of Excess relative risk (ERR) and Excess absolute risk (EAR) values.

Results: From the obtained results, the gEUD values for the rectum ranged from 51.04 Gy to 74.69 Gy and for the bladder from 27.22 Gy to 75.51 Gy. The maximum calculated risk values for the rectum and bladder were calculated to be 49.85% and 74.91%, respectively. Besides, a significant level of secondary cancer risk within the rectum and bladder was obtained for most of the studied patients. Furthermore, small values of secondary cancer risks were estimated for patients who were irradiated at older ages, and higher ones were obtained for patients who were irradiated at younger ages.
Conclusion: The results showed that there is a higher probability of developing secondary malignancies in the bladder than the rectum. The information obtained in this research can improve the performance of the treatment process, so that information about secondary cancers following radiation therapy for prostate cancer will ultimately help doctors design more effective and optimal treatment designs.

Keywords: chemotherapy, organs at risk, prostate cancer, radiotherapy, second cancer.

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Type of Study: Original Article |