S688
Clinical – Lower GI
ESTRO 2026
chemoradiation for rectal cancer: incidence, risk factors, and clinical course. Int J Radiat Oncol Biol Phys. 2009 Jul 1;74(3):818-23. doi: 10.1016/j.ijrobp.2008.08.054. [3]Rijpma-Jacobs L, et al. Pelvic insufficiency fractures and pelvic bone metastases after neoadjuvant (chemo)radiotherapy for rectal cancer. Acta Oncol. 2023 Oct;62(10):1295- 1300. doi: 10.1080/0284186X.2023.2252168 Keywords: PIFs, Rectum, Sacrum Digital Poster 792 Real-world outcomes of the RAPIDO total neoadjuvant therapy regimen for rectal cancer in a tertiary cancer centre Jingxue Hoo 1 , Jacinda Geok Gun Tan 1 , Shun Zi Liong 2 , Michael Lian Chek Wang 1 , Faye LWT Lim 1 , Fu Qiang Wang 1 , Tian Rui Siow 1 , Sharon Shuxian Poh 1 , Nelson Ling Fung Yit 1 , Iain Bee Huat Tan 3 , Si-Lin Koo 3 , Dawn Qingqing Chong 3 , Emile John Kwong Wei Tan 4 , Isaac En Seow 4 , Yvonne Ying Ru Ng 4 , Winson Jian Hong Tan 5 , Fung Joon Foo 5 , James Chi Yong Ngu 6 , Nan Zun Teo 6 , Connie Siew Poh Yip 1 1 Radiation Oncology, National Cancer Centre Singapore, Singapore, Singapore. 2 CTE-Biostatistics Unit, National Cancer Centre Singapore, Singapore, Singapore. 3 Medical Oncology, National Cancer Centre Singapore, Singapore, Singapore. 4 Colorectal Surgery, Singapore General Hospital, Singapore, Singapore. 5 Surgery, Sengkang General Hospital, Singapore, Singapore. 6 Surgery, Changi General Hospital, Singapore, Singapore Purpose/Objective: The study aimed to evaluate the clinical outcomes of locally advanced rectal cancer (LARC) treated with RAPIDO TNT in a tertiary cancer centre. Material/Methods: Patients who were treated with RAPIDO TNT for LARC between January 2017 and September 2024 were included in this retrospective analysis. All patients received SCRT (25Gy/5 fractions +/- optional tumour boost) followed by 6 cycles of XELOX or 9 cycles of FOLFOX chemotherapy. TME surgery was performed after completion of TNT. A resection margin of ≤ 1mm was considered positive. Local recurrence-free survival (LRFS), locoregional recurrence-free survival (LRRFS), disease-free survival (DFS) and overall survival (OS) were defined from the start of RT until the time of recurrence or death. LRFS and LRFFS analyses included patients who completed TNT and surgery. DFS and OS analyses included all patients who completed TNT regimen with or without surgery. Results: A total of 117 patients were included. Patient and tumour characteristics are shown in Table 1. Most
found in literature for PIFs incidence in general population [1], brings a significant difference between the populations (p-value = 0.0004).In addition, the number of fractures was adjusted to a Poisson distribution. The results were well under the fitting distribution using a λ =0.15 parameter. This new distribution was also compared to the one in the literature. Significant differences (p-value of 0.005, computed using a chi-square analysis) were also observed. On the other hand, no correlation was found between the PIFs and any of the dose-volume
parameters considered.
Conclusion: No significant differences were found for the incidence of PIFs for the patients assessed. However, when gender becomes a variable; it was found that radiotherapy might be a probable risk factor to take into account for PIFs in women. Calcium supplementation could be considered in women undergoing rectal cancer radiotherapy to counteract this complication as it is a common practice in other locations, such us cervical cancer. References: [1]Jørgensen JB, et al. Pelvic insufficiency fractures frequently occur following preoperative chemo- radiotherapy for rectal cancer - a nationwide MRI study. Colorectal Dis. 2018 Oct;20(10):873-880. doi: 10.1111/codi.14224.[2]Herman MP, et al. Sacral insufficiency fractures after preoperative
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